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Isu UH, Polasa A, Moradi M. Differential Behavior of Conformational Dynamics in Active and Inactive States of Cannabinoid Receptor 1. J Phys Chem B 2024. [PMID: 39169808 DOI: 10.1021/acs.jpcb.4c02828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
Cannabinoid receptor 1 (CB1) is a G protein-coupled receptor that regulates critical physiological processes including pain, appetite, and cognition. Understanding the conformational dynamics of CB1 associated with transitions between inactive and active signaling states is imperative for developing targeted modulators. Using microsecond-level all-atom molecular dynamics simulations, we identified marked differences in the conformational ensembles of inactive and active CB1 in apo. The inactive state exhibited substantially increased structural heterogeneity and plasticity compared to the more rigidified active state in the absence of stabilizing ligands. Transmembrane helices TM3 and TM7 were identified as distinguishing factors modulating the state-dependent dynamics. TM7 displayed amplified fluctuations selectively in the inactive state simulations attributed to disruption of conserved electrostatic contacts anchoring it to surrounding helices in the active state. Additionally, we identified significant reorganizations in key salt bridge and hydrogen bond networks contributing to the CB1 activation/inactivation. For instance, D213-Y224 hydrogen bond and D184-K192 salt bridge showed marked rearrangements between the states. Collectively, these findings reveal the specialized role of TM7 in directing state-dependent CB1 dynamics through electrostatic switch mechanisms. By elucidating the intrinsic enhanced flexibility of inactive CB1, this study provides valuable insights into the conformational landscape enabling functional transitions. Our perspective advances understanding of CB1 activation mechanisms and offers opportunities for structure-based drug discovery targeting the state-specific conformational dynamics of this receptor.
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Affiliation(s)
- Ugochi H Isu
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Adithya Polasa
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
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2
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Kramarska E, Toumi E, Squeglia F, Laverde D, Napolitano V, Frapy E, Autiero I, Sadones O, Huebner J, Skurnik D, Romero-Saavedra F, Berisio R. A rationally designed antigen elicits protective antibodies against multiple nosocomial Gram-positive pathogens. NPJ Vaccines 2024; 9:151. [PMID: 39155280 PMCID: PMC11330964 DOI: 10.1038/s41541-024-00940-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 07/30/2024] [Indexed: 08/20/2024] Open
Abstract
ESKAPE pathogens are responsible for complicated nosocomial infections worldwide and are often resistant to commonly used antibiotics in clinical settings. Among ESKAPE, vancomycin-resistant Enterococcus faecium (VREfm) and methicillin-resistant Staphylococcus aureus (MRSA) are two important Gram-positive pathogens for which non-antibiotic alternatives are urgently needed. We previously showed that the lipoprotein AdcA of E. faecium elicits opsonic and protective antibodies against E. faecium and E. faecalis. Prompted by our observation, reported here, that AdcA also elicits opsonic antibodies against MRSA and other clinically relevant Gram-positive pathogens, we identified the dominant epitope responsible for AdcA cross-reactive activity and designed a hyper-thermostable and multi-presenting antigen, Sc(EH)3. We demonstrate that antibodies raised against Sc(EH)3 mediate opsonic killing of a wide-spectrum of Gram-positive pathogens, including VREfm and MRSA, and confer protection both in passive and active immunisation models. Our data indicate that Sc(EH)3 is a promising antigen for the development of vaccines against different Gram-positive pathogens.
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Affiliation(s)
- Eliza Kramarska
- Institute of Biostructures and Bioimaging, Italian Research Council (CNR), Naples, Italy
| | - Eya Toumi
- CNRS, INSERM, Institut Necker-Enfants Malades, U1151-Equipe 11, Faculté de Médecine, University of Paris City, Paris, France
| | - Flavia Squeglia
- Institute of Biostructures and Bioimaging, Italian Research Council (CNR), Naples, Italy
| | - Diana Laverde
- Division of Paediatric Infectious Disease, Hauner Children's Hospital LMU, LMU, Munich, Germany
| | - Valeria Napolitano
- Institute of Biostructures and Bioimaging, Italian Research Council (CNR), Naples, Italy
| | - Eric Frapy
- CNRS, INSERM, Institut Necker-Enfants Malades, U1151-Equipe 11, Faculté de Médecine, University of Paris City, Paris, France
| | - Ida Autiero
- Institute of Biostructures and Bioimaging, Italian Research Council (CNR), Naples, Italy
| | - Oceane Sadones
- Division of Paediatric Infectious Disease, Hauner Children's Hospital LMU, LMU, Munich, Germany
| | - Johannes Huebner
- Division of Paediatric Infectious Disease, Hauner Children's Hospital LMU, LMU, Munich, Germany
| | - David Skurnik
- CNRS, INSERM, Institut Necker-Enfants Malades, U1151-Equipe 11, Faculté de Médecine, University of Paris City, Paris, France.
- Department of Clinical Microbiology, Fédération Hospitalo-Universitaire Prématurité (FHU PREMA), Necker-Enfants Malades University Hospital, Assistance Publique-Hôpitaux de Paris, University of Paris City, Paris, France.
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
| | - Felipe Romero-Saavedra
- Division of Paediatric Infectious Disease, Hauner Children's Hospital LMU, LMU, Munich, Germany.
| | - Rita Berisio
- Institute of Biostructures and Bioimaging, Italian Research Council (CNR), Naples, Italy.
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3
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Tzfadia O, Gijsbers A, Vujkovic A, Snobre J, Vargas R, Dewaele K, Meehan CJ, Farhat M, Hakke S, Peters PJ, de Jong BC, Siroy A, Ravelli RBG. Single nucleotide variation catalog from clinical isolates mapped on tertiary and quaternary structures of ESX-1-related proteins reveals critical regions as putative Mtb therapeutic targets. Microbiol Spectr 2024; 12:e0381623. [PMID: 38874407 PMCID: PMC11302016 DOI: 10.1128/spectrum.03816-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 05/02/2024] [Indexed: 06/15/2024] Open
Abstract
Proteins encoded by the ESX-1 genes of interest are essential for full virulence in all Mycobacterium tuberculosis complex (Mtbc) lineages, the pathogens causing the highest mortality worldwide. Identifying critical regions in these ESX-1-related proteins could provide preventive or therapeutic targets for Mtb infection, the game changer needed for tuberculosis control. We analyzed a compendium of whole genome sequences of clinical Mtb isolates from all lineages from >32,000 patients and identified single nucleotide polymorphisms. When mutations corresponding to all non-synonymous single nucleotide polymorphisms were mapped on structural models of the ESX-1 proteins, fully conserved regions emerged. Some could be assigned to known quaternary structures, whereas others could be predicted to be involved in yet-to-be-discovered interactions. Some mutants had clonally expanded (found in >1% of the isolates); these mutants were mostly located at the surface of globular domains, remote from known intra- and inter-molecular protein-protein interactions. Fully conserved intrinsically disordered regions of proteins were found, suggesting that these regions are crucial for the pathogenicity of the Mtbc. Altogether, our findings highlight fully conserved regions of proteins as attractive vaccine antigens and drug targets to control Mtb virulence. Extending this approach to the whole Mtb genome as well as other microorganisms will enhance vaccine development for various pathogens. IMPORTANCE We mapped all non-synonymous single nucleotide polymorphisms onto each of the experimental and predicted ESX-1 proteins' structural models and inspected their placement. Varying sizes of conserved regions were found. Next, we analyzed predicted intrinsically disordered regions within our set of proteins, finding two putative long stretches that are fully conserved, and discussed their potential essential role in immunological recognition. Combined, our findings highlight new targets for interfering with Mycobacterium tuberculosis complex virulence.
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Affiliation(s)
- Oren Tzfadia
- Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium
| | - Abril Gijsbers
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Alexandra Vujkovic
- Clinical Virology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- ADReM Data Lab, University of Antwerp, Antwerp, Belgium
| | - Jihad Snobre
- Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium
| | - Roger Vargas
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, USA
| | - Klaas Dewaele
- Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium
| | - Conor J. Meehan
- Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Department of Biosciences, Nottingham Trent University, Nottingham, United Kingdom
| | - Maha Farhat
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, USA
| | - Sneha Hakke
- Division of Nanoscopy, Maastricht Multimodal Imaging Institute (M4i), Maastricht University, Maastricht, the Netherlands
| | - Peter J. Peters
- Division of Nanoscopy, Maastricht Multimodal Imaging Institute (M4i), Maastricht University, Maastricht, the Netherlands
| | - Bouke C. de Jong
- Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium
| | - Axel Siroy
- Unité de soutien à l'Institut Européen de Chimie et Biologie (IECB), CNRS, INSERM, IECB, US1, Université de Bordeaux, Pessac, France
| | - Raimond B. G. Ravelli
- Division of Nanoscopy, Maastricht Multimodal Imaging Institute (M4i), Maastricht University, Maastricht, the Netherlands
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4
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Zhang W, Liu K, Kong F, Ye T, Wang T. Multiple Functions of Compatible Solute Ectoine and Strategies for Constructing Overproducers for Biobased Production. Mol Biotechnol 2024; 66:1772-1785. [PMID: 37488320 DOI: 10.1007/s12033-023-00827-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 07/14/2023] [Indexed: 07/26/2023]
Abstract
Ectoine and its derivative 5-hydroxyectoine are compatible solutes initially found in the hyperhalophilic bacterium Ectothiorhodospira halochloris, which inhabits the desert in Egypt. The habitat of ectoine producers implies the primary function of ectoine as a cytoprotectant against harsh conditions such as high salinity, drought, and high radiation. More extensive and in-depth studies have revealed the multiple functions of ectoine in its native producer bacterial cells and other types of cells and its biomolecular components (such as proteins and DNA) as a general protective agent. Its chemical properties as a bio-based amino acid derivative make it attractive for basic scientific research and related industries, such as the food/agricultural industry, cosmetic manufacturing, biologics, and therapeutic agent preparation. This article first discusses the functions and applications of ectoine and 5-hydroxyectoine. Subsequently, more emphasis was placed on advances in bio-based ectoine and/or 5-hydroxyectoine production. Strategies for developing more robust cell factories for highly efficient ectoine and/or 5-hydroxyectoine production are further discussed. We hope this review will provide a valuable reference for studies on the bio-based production of ectoine and 5-hydroxyectoine.
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Affiliation(s)
- Wei Zhang
- College of Life Sciences, Xinyang Normal University, Xinyang, 464000, People's Republic of China
| | - Kun Liu
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Fang Kong
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Tao Ye
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Tianwen Wang
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China.
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5
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Reddy DJ, Guntuku G, Palla MS. Advancements in nanobody generation: Integrating conventional, in silico, and machine learning approaches. Biotechnol Bioeng 2024. [PMID: 39054738 DOI: 10.1002/bit.28816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 07/08/2024] [Accepted: 07/13/2024] [Indexed: 07/27/2024]
Abstract
Nanobodies, derived from camelids and sharks, offer compact, single-variable heavy-chain antibodies with diverse biomedical potential. This review explores their generation methods, including display techniques on phages, yeast, or bacteria, and computational methodologies. Integrating experimental and computational approaches enhances understanding of nanobody structure and function. Future trends involve leveraging next-generation sequencing, machine learning, and artificial intelligence for efficient candidate selection and predictive modeling. The convergence of traditional and computational methods promises revolutionary advancements in precision biomedical applications such as targeted drug delivery and diagnostics. Embracing these technologies accelerates nanobody development, driving transformative breakthroughs in biomedicine and paving the way for precision medicine and biomedical innovation.
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Affiliation(s)
- D Jagadeeswara Reddy
- Pharmaceutical Biotechnology Division, A.U. College of Pharmaceutical Sciences, Andhra University, Visakhapatnam, India
| | - Girijasankar Guntuku
- Pharmaceutical Biotechnology Division, A.U. College of Pharmaceutical Sciences, Andhra University, Visakhapatnam, India
| | - Mary Sulakshana Palla
- GITAM School of Pharmacy, GITAM Deemed to be University, Rushikonda, Visakhapatnam, India
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6
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Heard SC, Winter JM. Structural, biochemical and bioinformatic analyses of nonribosomal peptide synthetase adenylation domains. Nat Prod Rep 2024; 41:1180-1205. [PMID: 38488017 PMCID: PMC11253843 DOI: 10.1039/d3np00064h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Indexed: 07/18/2024]
Abstract
Covering: 1997 to July 2023The adenylation reaction has been a subject of scientific intrigue since it was first recognized as essential to many biological processes, including the homeostasis and pathogenicity of some bacteria and the activation of amino acids for protein synthesis in mammals. Several foundational studies on adenylation (A) domains have facilitated an improved understanding of their molecular structures and biochemical properties, in particular work on nonribosomal peptide synthetases (NRPSs). In NRPS pathways, A domains activate their respective acyl substrates for incorporation into a growing peptidyl chain, and many nonribosomal peptides are bioactive. From a natural product drug discovery perspective, improving existing bioinformatics platforms to predict unique NRPS products more accurately from genomic data is desirable. Here, we summarize characterization efforts of A domains primarily from NRPS pathways from July 1997 up to July 2023, covering protein structure elucidation, in vitro assay development, and in silico tools for improved predictions.
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Affiliation(s)
- Stephanie C Heard
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA.
| | - Jaclyn M Winter
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA.
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7
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Boreak N, Al Mahde RZ, Otayn WA, Alamer AY, Alrajhi T, Jafri S, Sharwani A, Swaidi E, Abozoah S, Mowkly AAM. Exploring Plant-Based Compounds as Alternatives for Targeting Enterococcus faecalis in Endodontic Therapy: A Molecular Docking Approach. Int J Mol Sci 2024; 25:7727. [PMID: 39062969 PMCID: PMC11276846 DOI: 10.3390/ijms25147727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 07/07/2024] [Accepted: 07/09/2024] [Indexed: 07/28/2024] Open
Abstract
Endodontic infections pose significant challenges in dental practice due to their persistence and potential complications. Among the causative agents, Enterococcus faecalis stands out for its ability to form biofilms and develop resistance to conventional antibiotics, leading to treatment failures and recurrent infections. The urgent need for alternative treatments arises from the growing concern over antibiotic resistance and the limitations of current therapeutic options in combating E. faecalis-associated endodontic infections. Plant-based natural compounds offer a promising avenue for exploration, given their diverse bioactive properties and potential as sources of novel antimicrobial agents. In this study, molecular docking and dynamics simulations are employed to explore the interactions between SrtA, a key enzyme in E. faecalis, and plant-based natural compounds. Analysis of phytocompounds through molecular docking unveiled several candidates with binding energies surpassing that of the control drug, ampicillin, with pinocembrin emerging as the lead compound due to its strong interactions with key residues of SrtA. Comparative analysis with ampicillin underscored varying degrees of structural similarity among the study compounds. Molecular dynamics simulations provided deeper insights into the dynamic behavior and stability of protein-ligand complexes, with pinocembrin demonstrating minimal conformational changes and effective stabilization of the N-terminal region. Free energy landscape analysis supported pinocembrin's stabilizing effects, further corroborated by hydrogen bond analysis. Additionally, physicochemical properties analysis highlighted the drug-likeness of pinocembrin and glabridin. Overall, this study elucidates the potential anti-bacterial properties of selected phytocompounds against E. faecalis infections, with pinocembrin emerging as a promising lead compound for further drug development efforts, offering new avenues for combating bacterial infections and advancing therapeutic interventions in endodontic practice.
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Affiliation(s)
- Nezar Boreak
- Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia; (R.Z.A.M.); (A.Y.A.); (T.A.); (S.J.); (A.S.)
| | - Rahf Zuhair Al Mahde
- Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia; (R.Z.A.M.); (A.Y.A.); (T.A.); (S.J.); (A.S.)
| | - Waseem Ahmed Otayn
- Specialized Dental Canter, Ministry of Health, Jazan 45142, Saudi Arabia; (W.A.O.)
| | - Amwaj Yahya Alamer
- Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia; (R.Z.A.M.); (A.Y.A.); (T.A.); (S.J.); (A.S.)
| | - Taif Alrajhi
- Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia; (R.Z.A.M.); (A.Y.A.); (T.A.); (S.J.); (A.S.)
| | - Shatha Jafri
- Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia; (R.Z.A.M.); (A.Y.A.); (T.A.); (S.J.); (A.S.)
| | - Amnah Sharwani
- Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia; (R.Z.A.M.); (A.Y.A.); (T.A.); (S.J.); (A.S.)
| | - Entesar Swaidi
- Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia; (R.Z.A.M.); (A.Y.A.); (T.A.); (S.J.); (A.S.)
| | - Shahad Abozoah
- Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia; (R.Z.A.M.); (A.Y.A.); (T.A.); (S.J.); (A.S.)
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8
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Yang W, Mei FC, Lin W, White MA, Li L, Li Y, Pan S, Cheng X. Protein SUMOylation promotes cAMP-independent EPAC1 activation. Cell Mol Life Sci 2024; 81:283. [PMID: 38963422 PMCID: PMC11335207 DOI: 10.1007/s00018-024-05315-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/20/2024] [Accepted: 06/12/2024] [Indexed: 07/05/2024]
Abstract
Protein SUMOylation is a prevalent stress-response posttranslational modification crucial for maintaining cellular homeostasis. Herein, we report that protein SUMOylation modulates cellular signaling mediated by cAMP, an ancient and universal stress-response second messenger. We identify K561 as a primary SUMOylation site in exchange protein directly activated by cAMP (EPAC1) via site-specific mapping of SUMOylation using mass spectrometry. Sequence and site-directed mutagenesis analyses reveal that a functional SUMO-interacting motif in EPAC1 is required for the binding of SUMO-conjugating enzyme UBC9, formation of EPAC1 nuclear condensate, and EPAC1 cellular SUMOylation. Heat shock-induced SUMO modification of EPAC1 promotes Rap1/2 activation in a cAMP-independent manner. Structural modeling and molecular dynamics simulation studies demonstrate that SUMO substituent on K561 of EPAC1 promotes Rap1 interaction by increasing the buried surface area between the SUMOylated receptor and its effector. Our studies identify a functional SUMOylation site in EPAC1 and unveil a novel mechanism in which SUMOylation of EPAC1 leads to its autonomous activation. The findings of SUMOylation-mediated activation of EPAC1 not only provide new insights into our understanding of cellular regulation of EPAC1 but also will open up a new field of experimentation concerning the cross-talk between cAMP/EPAC1 signaling and protein SUMOylation, two major cellular stress response pathways, during cellular homeostasis.
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Affiliation(s)
- Wenli Yang
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, TX, USA
- Texas Therapeutics Institute, The University of Texas Health Science Center, Houston, TX, USA
- Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, TX, USA
| | - Fang C Mei
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, TX, USA
- Texas Therapeutics Institute, The University of Texas Health Science Center, Houston, TX, USA
- Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, TX, USA
| | - Wei Lin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, TX, USA
- Texas Therapeutics Institute, The University of Texas Health Science Center, Houston, TX, USA
- Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, TX, USA
| | - Mark A White
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Li Li
- Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, TX, USA
| | - Yue Li
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, TX, USA
- Cell Therapy Manufacturing Center, 2130 W Holcombe Blvd, Houston, TX, 77030, USA
| | - Sheng Pan
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, TX, USA
- Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, TX, USA
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, TX, USA.
- Texas Therapeutics Institute, The University of Texas Health Science Center, Houston, TX, USA.
- Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, TX, USA.
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9
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Tare DS, Pawar SD, Shil P, Atre NM. Structural and functional characterization of avian influenza H9N2 virus neuraminidase with a combination of five novel mutations. Arch Biochem Biophys 2024; 757:110041. [PMID: 38750923 DOI: 10.1016/j.abb.2024.110041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 05/08/2024] [Accepted: 05/12/2024] [Indexed: 05/20/2024]
Abstract
The influenza virus neuraminidase (NA) protein is responsible for actively cleaving the sialic acid (SA) bound to the viral hemagglutinin. In the present study, we identified a combination of five novel amino acid substitutions in the NA, conferring increased substrate binding and altered surface characteristics to a low pathogenic avian influenza (LPAI) H9N2 virus strain. The H9N2 strain reported from India, A/Environmental/India/1726265/2017 (H9N2-1726265) showed the combination of amino acid substitutions T149I, R249W, G346A, W403R and G435R, which were in the vicinity of the enzyme active site cavity. The strain A/chicken/India/99321/2009 (H9N2-99321) did not show these substitutions and was used for comparison. Virus elution was studied using turkey red blood cells (tRBCs). NA enzyme kinetics assays were carried out using the MUNANA substrate, which is an SA analogue. Homology modelling and molecular docking were performed to determine alterations in the surface characteristics and substrate binding. H9N2-1726265 showed enhanced elution from tRBCs. Enzyme kinetics revealed a lower KM of H9N2-1726265 (111.5 μM) as compared to H9N2-99321 (135.2 μM), indicating higher substrate binding affinity of H9N2-1726265, due to which the NA enzyme cleaved the SA more efficiently, leading to faster elution. Molecular docking revealed a greater number of binding interactions of H9N2-1726265 to SA as compared to H9N2-99321 corroborating the greater substrate binding affinity. Changes in the surface charge, hydrophobicity, and contour, were observed in H9N2-1726265 NA due to the five substitutions. Thus, the novel combination of five amino acids near the sialic acid binding site of NA, resulted in altered surface characteristics, higher substrate binding affinity, and virus elution.
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Affiliation(s)
- Deeksha S Tare
- ICMR-National Institute of Virology, 130/1, Sus Road, Pashan, Pune, 411021, India
| | - Shailesh D Pawar
- ICMR-National Institute of Virology, 130/1, Sus Road, Pashan, Pune, 411021, India.
| | - Pratip Shil
- ICMR-National Institute of Virology, 130/1, Sus Road, Pashan, Pune, 411021, India
| | - Nitin M Atre
- ICMR-National Institute of Virology, 130/1, Sus Road, Pashan, Pune, 411021, India
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Xavier G, Lima Farias de Sousa AC, Queiroz Dos Santos L, Aguiar D, Gonçalves E, Santos Siqueira A. Structural and functional analysis of Cyanovirin-N homologs: Carbohydrate binding affinities and antiviral potential of cyanobacterial peptides. J Mol Graph Model 2024; 129:108718. [PMID: 38382198 DOI: 10.1016/j.jmgm.2024.108718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 01/23/2024] [Accepted: 01/23/2024] [Indexed: 02/23/2024]
Abstract
Cyanobacteria, a group of photosynthetic prokaryotes, can sinthesize several substances due to their secondary metabolism, with notable properties, such as Cyanovirin-N(CVN), a carbohydrate-binding lectin, that exhibits antiviral activity against several pathogens, due to its ability to bind viral surface carbohydrates such as mannose, thus interfering with the viral entry on the cell. CVN has been described in several cyanobacterial strains and shows biotechnological potential for the development of drugs of pharmaceutical interest. This study focuses on the genomic exploration and characterization of Cyanovirin-N homologs to assess the conservation of carbohydrate-binding affinity within the group. The analysis of their antiviral properties was carried out using bioinformatics tools to study protein models through an in silico pipeline, following the steps of genomic prospection on public databases, homology modeling, docking, molecular dynamics and energetic analysis. Mannose served as the reference ligand, and the lectins' binding affinity with mannose was assessed across Cyanovirin-N homologs. Genomic mining identified 33 cyanobacterial lectin sequences, which underwent structural and functional characterization. The results obtained from this work indicate strong carbohydrate affinity on several homologs, pointing to the conservation of antiviral properties alongside the group. However, this affinity was not uniformly distributed among sequences, exhibiting significant heterogeneity in binding site residues, suggesting potential multi-ligand binding capabilities on the Cyanovirin-N homologs group. Studies focused on the properties involved in these molecules and the investigation of the genetic diversity of Cyanovirin-N homologs could provide valuable insights into the discovery of new drug candidates, harvesting the potential of bioinformatics for large-scale functional and structural analysis.
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Affiliation(s)
- Gabriel Xavier
- Biomolecular Technology Laboratory/Institute of Biological Sciences, Federal University of Pará, Belém-PA, Brazil.
| | | | - Larissa Queiroz Dos Santos
- Biomolecular Technology Laboratory/Institute of Biological Sciences, Federal University of Pará, Belém-PA, Brazil
| | - Délia Aguiar
- Biomolecular Technology Laboratory/Institute of Biological Sciences, Federal University of Pará, Belém-PA, Brazil
| | - Evonnildo Gonçalves
- Biomolecular Technology Laboratory/Institute of Biological Sciences, Federal University of Pará, Belém-PA, Brazil
| | - Andrei Santos Siqueira
- Biomolecular Technology Laboratory/Institute of Biological Sciences, Federal University of Pará, Belém-PA, Brazil
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Gloriam D, Thorsen T, Kulkarni Y, Sykes D, Bøggild A, Drace T, Hompluem P, Iliopoulos-Tsoutsouvas C, Nikas S, Daver H, Makriyannis A, Nissen P, Gajhede M, Veprintsev D, Boesen T, Kastrup J. Structural basis of Δ 9-THC analog activity at the Cannabinoid 1 receptor. RESEARCH SQUARE 2024:rs.3.rs-4277209. [PMID: 38826401 PMCID: PMC11142349 DOI: 10.21203/rs.3.rs-4277209/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Δ9-tetrahydrocannabinol (THC) is the principal psychoactive compound derived from the cannabis plant Cannabis sativa and approved for emetic conditions, appetite stimulation and sleep apnea relief. THC's psychoactive actions are mediated primarily by the cannabinoid receptor CB1. Here, we determine the cryo-EM structure of HU210, a THC analog and widely used tool compound, bound to CB1 and its primary transducer, Gi1. We leverage this structure for docking and 1,000 ns molecular dynamics simulations of THC and 10 structural analogs delineating their spatiotemporal interactions at the molecular level. Furthermore, we pharmacologically profile their recruitment of Gi and β-arrestins and reversibility of binding from an active complex. By combining detailed CB1 structural information with molecular models and signaling data we uncover the differential spatiotemporal interactions these ligands make to receptors governing potency, efficacy, bias and kinetics. This may help explain the actions of abused substances, advance fundamental receptor activation studies and design better medicines.
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12
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Isu UH, Polasa A, Moradi M. Differential Behavior of Conformational Dynamics in Active and Inactive States of Cannabinoid Receptor 1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.17.589939. [PMID: 38659869 PMCID: PMC11042334 DOI: 10.1101/2024.04.17.589939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The cannabinoid receptor CB1 is a G protein-coupled receptor that regulates critical physiological processes including pain, appetite, and cognition. Understanding the conformational dynamics of CB1 associated with transitions between inactive and active signaling states is imperative for developing targeted modulators. Using microsecond-level all-atom molecular dynamics simulations, we identified marked differences in the conformational ensembles of inactive and active CB1 states in apo conditions. The inactive state exhibited substantially increased structural heterogeneity and plasticity compared to the more rigidified active state in the absence of stabilizing ligands. Transmembrane helices TM3 and TM7 were identified as distinguishing factors modulating the state-dependent dynamics. TM7 displayed amplified fluctuations selectively in the inactive state simulations attributed to disruption of conserved electrostatic contacts anchoring it to surrounding helices in the active state. Additionally, we identified significant reorganization of key salt bridge and hydrogen bond networks known to control CB1 activation between states. For instance, a conserved D213-Y224 hydrogen bond and D184-K192 salt bridge interactions showed marked rearrangements between the states. Collectively, these findings reveal the specialized role of TM7 in directing state-dependent CB1 dynamics through electrostatic switch mechanisms. By elucidating the intrinsic enhanced flexibility of inactive CB1, this study provides valuable insights into the conformational landscape enabling functional transitions. Our perspective advances understanding of CB1 activation mechanisms and offers opportunities for structure-based drug discovery targeting the state-specific conformational dynamics of this receptor.
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13
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Miller AP, O'Neill SE, Lampi KJ, Reichow SL. The α-crystallin Chaperones Undergo a Quasi-ordered Co-aggregation Process in Response to Saturating Client Interaction. J Mol Biol 2024; 436:168499. [PMID: 38401625 PMCID: PMC11001518 DOI: 10.1016/j.jmb.2024.168499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 02/15/2024] [Accepted: 02/16/2024] [Indexed: 02/26/2024]
Abstract
Small heat shock proteins (sHSPs) are ATP-independent chaperones vital to cellular proteostasis, preventing protein aggregation events linked to various human diseases including cataract. The α-crystallins, αA-crystallin (αAc) and αB-crystallin (αBc), represent archetypal sHSPs that exhibit complex polydispersed oligomeric assemblies and rapid subunit exchange dynamics. Yet, our understanding of how this plasticity contributes to chaperone function remains poorly understood. Using biochemical and biophysical analyses combined with single-particle electron microscopy (EM), we examined structural changes in αAc, αBc and native heteromeric lens α-crystallins (αLc) in their apo-states and at varying degree of chaperone saturation leading to co-aggregation, using lysozyme and insulin as model clients. Quantitative single-particle analysis unveiled a continuous spectrum of oligomeric states formed during the co-aggregation process, marked by significant client-triggered expansion and quasi-ordered elongation of the sHSP oligomeric scaffold, whereby the native cage-like sHSP assembly displays a directional growth to accommodate saturating conditions of client sequestration. These structural modifications culminated in an apparent amorphous collapse of chaperone-client complexes, resulting in the creation of co-aggregates capable of scattering visible light. Intriguingly, these co-aggregates maintain internal morphological features of highly elongated sHSP oligomers with striking resemblance to polymeric α-crystallin species isolated from aged lens tissue. This mechanism appears consistent across αAc, αBc and αLc, albeit with varying degrees of susceptibility to client-induced co-aggregation. Importantly, our findings suggest that client-induced co-aggregation follows a distinctive mechanistic and quasi-ordered trajectory, distinct from a purely amorphous process. These insights reshape our understanding of the physiological and pathophysiological co-aggregation processes of α-crystallins, carrying potential implications for a pathway toward cataract formation.
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Affiliation(s)
- Adam P Miller
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA; Department of Chemistry, Portland State University, Portland, OR 97201, USA
| | - Susan E O'Neill
- Department of Chemistry, Portland State University, Portland, OR 97201, USA
| | - Kirsten J Lampi
- Biomaterial and Biomedical Sciences, Oregon Health & Science University, Portland, OR 97239, USA
| | - Steve L Reichow
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA; Department of Chemistry, Portland State University, Portland, OR 97201, USA.
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14
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Leighton SE, Wong RS, Lucaciu SA, Hauser A, Johnston D, Stathopulos PB, Bai D, Penuela S, Laird DW. Cx31.1 can selectively intermix with co-expressed connexins to facilitate its assembly into gap junctions. J Cell Sci 2024; 137:jcs261631. [PMID: 38533727 PMCID: PMC11058089 DOI: 10.1242/jcs.261631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 03/05/2024] [Indexed: 03/28/2024] Open
Abstract
Connexins are channel-forming proteins that function to facilitate gap junctional intercellular communication. Here, we use dual cell voltage clamp and dye transfer studies to corroborate past findings showing that Cx31.1 (encoded by GJB5) is defective in gap junction channel formation, illustrating that Cx31.1 alone does not form functional gap junction channels in connexin-deficient mammalian cells. Rather Cx31.1 transiently localizes to the secretory pathway with a subpopulation reaching the cell surface, which is rarely seen in puncta reminiscent of gap junctions. Intracellular retained Cx31.1 was subject to degradation as Cx31.1 accumulated in the presence of proteasomal inhibition, had a faster turnover when Cx43 was present and ultimately reached lysosomes. Although intracellularly retained Cx31.1 was found to interact with Cx43, this interaction did not rescue its delivery to the cell surface. Conversely, the co-expression of Cx31 dramatically rescued the assembly of Cx31.1 into gap junctions where gap junction-mediated dye transfer was enhanced. Collectively, our results indicate that the localization and functional status of Cx31.1 is altered through selective interplay with co-expressed connexins, perhaps suggesting Cx31.1 is a key regulator of intercellular signaling in keratinocytes.
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Affiliation(s)
- Stephanie E. Leighton
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Robert S. Wong
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Sergiu A. Lucaciu
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Alexandra Hauser
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Danielle Johnston
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Donglin Bai
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Western's Bone and Joint Institute, The Dr. Sandy Kirkley Centre for Musculoskeletal Research, University Hospital, London, ON N6A 5B9, Canada
- Division of Experimental Oncology, Department of Oncology, University of Western Ontario, London, ON N6A 5W9, Canada
| | - Dale W. Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
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15
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Zhang C, Ran F, Du L, Wang X, Liu L, Liu J, Chen Q, Cao Y, Bi L, Hang H. The Humanization and Maturation of an Anti-PrPc Antibody. Bioengineering (Basel) 2024; 11:242. [PMID: 38534516 DOI: 10.3390/bioengineering11030242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 01/26/2024] [Accepted: 02/01/2024] [Indexed: 03/28/2024] Open
Abstract
The cellular prion protein (PrPc) is a cell surface glycoprotein that is highly expressed in a variety of cancer tissues in addition to the nervous system, and its elevated expression is correlated to poor prognosis in many cancer patients. Our team previously found that patients with colorectal cancer (CRC) with high-level PrPc expression had significantly poorer survival than those with no or low-level PrPc expression. Mouse antibodies for PrPc inhibited tumor initiation and liver metastasis of PrPc-positive human CRC cells in mouse model experiments. PrPc is a candidate target for CRC therapy. In this study, we newly cloned a mouse anti-PrPc antibody (Clone 6) and humanized it, then affinity-matured this antibody using a CHO cell display with a peptide antigen and full-length PrPc, respectively. We obtained two humanized antibody clones with affinities toward a full-length PrPc of about 10- and 100-fold of that of the original antibody. The two humanized antibodies bound to the PrPc displayed significantly better on the cell surface than Clone 6. Used for Western blotting and immunohistochemistry, the humanized antibody with the highest affinity is superior to the two most frequently used commercial antibodies (8H4 and 3F4). The two new antibodies have the potential to be developed as useful reagents for PrPc detection and even therapeutic antibodies targeting PrPc-positive cancers.
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Affiliation(s)
- Cheng Zhang
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fanlei Ran
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Du
- The State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing 100101, China
| | - Xiaohui Wang
- The State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Lei Liu
- The State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing 100101, China
| | - Jinming Liu
- The State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Quan Chen
- The State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yang Cao
- Center of Growth, Metabolism and Aging, Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China
| | - Lijun Bi
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haiying Hang
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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16
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Sun F, Deng Y, Ma X, Liu Y, Zhao L, Yu S, Zhang L. Structure-based prediction of protein-protein interaction network in rice. Genet Mol Biol 2024; 47:e20230068. [PMID: 38314883 PMCID: PMC10849033 DOI: 10.1590/1678-4685-gmb-2023-0068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 10/02/2023] [Indexed: 02/07/2024] Open
Abstract
Comprehensive protein-protein interaction (PPI) maps are critical for understanding the functional organization of the proteome, but challenging to produce experimentally. Here, we developed a computational method for predicting PPIs based on protein docking. Evaluation of performance on benchmark sets demonstrated the ability of the docking-based method to accurately identify PPIs using predicted protein structures. By employing the docking-based method, we constructed a structurally resolved PPI network consisting of 24,653 interactions between 2,131 proteins, which greatly extends the current knowledge on the rice protein-protein interactome. Moreover, we mapped the trait-associated single nucleotide polymorphisms (SNPs) to the structural interactome, and computationally identified 14 SNPs that had significant consequences on PPI network. The protein structural interactome map provided a resource to facilitate functional investigation of PPI-perturbing alleles associated with agronomically important traits in rice.
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Affiliation(s)
- Fangnan Sun
- Shanghai Jiao Tong University, School of Agriculture and Biology, Department of Plant Science, Shanghai, China
| | - Yaxin Deng
- Shanghai Jiao Tong University, School of Agriculture and Biology, Department of Plant Science, Shanghai, China
| | - Xiaosong Ma
- Shanghai Academy of Agricultural Sciences, Shanghai Agrobiological Gene Center, Shanghai, China
| | - Yuan Liu
- Shanghai Jiao Tong University, School of Agriculture and Biology, Department of Plant Science, Shanghai, China
| | - Lingxia Zhao
- Shanghai Jiao Tong University, School of Agriculture and Biology, Department of Plant Science, Shanghai, China
| | - Shunwu Yu
- Shanghai Academy of Agricultural Sciences, Shanghai Agrobiological Gene Center, Shanghai, China
| | - Lida Zhang
- Shanghai Jiao Tong University, School of Agriculture and Biology, Department of Plant Science, Shanghai, China
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17
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Wong RS, Chen H, Li YX, Esseltine JL, Stathopulos PB, Bai D. Human Cx50 Isoleucine177 prevents heterotypic docking and formation of functional gap junction channels with Cx43. Am J Physiol Cell Physiol 2024; 326:C414-C428. [PMID: 38145302 DOI: 10.1152/ajpcell.00634.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 12/18/2023] [Accepted: 12/18/2023] [Indexed: 12/26/2023]
Abstract
The human lens is an avascular organ, and its transparency is dependent on gap junction (GJ)-mediated microcirculation. Lens GJs are composed of three connexins with Cx46 and Cx50 being expressed in lens fiber cells and Cx43 and Cx50 in the epithelial cells. Impairment of GJ communication by either Cx46 or Cx50 mutations has been shown to be one of the main molecular mechanisms of congenital cataracts in mutant carrier families. The docking compatibility and formation of functional heterotypic GJs for human lens connexins have not been studied. Previous study on rodent lens connexins revealed that Cx46 can form functional heterotypic GJs with Cx50 and Cx43, but Cx50 cannot form heterotypic GJ with Cx43 due to its second extracellular (EL2) domain. To study human lens connexin docking and formation of functional heterotypic GJs, we developed a genetically engineered HEK293 cell line with endogenously expressed Cx43 and Cx45 ablated. The human lens connexins showed docking compatibility identical to those found in the rodent connexins. To reveal the structural mechanisms of the docking incompatibility between Cx50 and Cx43, we designed eight variants based on the differences between the EL2 of Cx50 and Cx46. We found that Cx50I177L is sufficient to establish heterotypic docking with Cx43 with some interesting gating properties. Our structure models indicate this residue is important for interdomain interactions within a single connexin, Cx50 I177L showed an increased interdomain interaction which might alter the docking interface structure to be compatible with Cx43.NEW & NOTEWORTHY The human lens is an avascular organ, and its transparency is partially dependent on gap junction (GJ) network composed of Cx46, Cx50, and Cx43. We found that human Cx46 can dock and form functional heterotypic GJs with Cx50 and Cx43, but Cx50 is unable to form functional heterotypic GJs with Cx43. Through mutagenesis and patch-clamp study of several designed variants, we found that Cx50 I177L was sufficient to form functional heterotypic GJs with Cx43.
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Affiliation(s)
- Robert S Wong
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Honghong Chen
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Yi X Li
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Jessica L Esseltine
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Donglin Bai
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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18
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Pochini L, Barone F, Console L, Brunocilla C, Galluccio M, Scalise M, Indiveri C. OCTN1 (SLC22A4) displays two different transport pathways for organic cations or zwitterions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184263. [PMID: 38092232 DOI: 10.1016/j.bbamem.2023.184263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/15/2023] [Accepted: 12/08/2023] [Indexed: 12/19/2023]
Abstract
BACKGROUND OCTN1 belongs to the SLC22 family, which includes transporters for cationic, zwitterionic, and anionic substrates. OCTN1 function and role in cells are still poorly understood. Not only cations, such as TEA, but also zwitterions, such as carnitine and ergothioneine, figure among transported molecules. METHODS In this work, we carried out transport assays measuring [14C]-TEA and [3H]-Carnitine in proteoliposomes reconstituted with the recombinant human OCTN1 in the presence of Na+ or other cations. The homology model of OCTN1 was built using the structure of OCT3 as a template for docking analysis. RESULTS TEA and carnitine did not inhibit each other. Moreover, carnitine uptake was not affected by the presence of Na+ and TEBA, whereas TEA was strongly inhibited by both compounds. Computational data revealed that TEA, Na+, and carnitine can interact with E381 in the OCTN1 substrate site. Differently from TEA, in the presence of Na+, carnitine is still able to interact with the binding site via R469. CONCLUSIONS The lack of mutual inhibition of the two prototype substrates, the different effect of Na+ and TEBA on their transport reaction, together with the computational analysis supports the existence of two transport pathways for cations and zwitterions. GENERAL SIGNIFICANCE The results shed new light on the transport mechanisms of OCTN1, helping to get further insights into the structure/function relationships. The described results correlate well with previous and very recent findings on the polyspecificity of the OCT group of transporters belonging to the same family.
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Affiliation(s)
- Lorena Pochini
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, Via Bucci 4C, 6C, 87036 Arcavacata di Rende, Italy; National Research Council (CNR), Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), via Amendola 122/O, 70126 Bari, Italy
| | - Francesca Barone
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, Via Bucci 4C, 6C, 87036 Arcavacata di Rende, Italy
| | - Lara Console
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, Via Bucci 4C, 6C, 87036 Arcavacata di Rende, Italy
| | - Chiara Brunocilla
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, Via Bucci 4C, 6C, 87036 Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, Via Bucci 4C, 6C, 87036 Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, Via Bucci 4C, 6C, 87036 Arcavacata di Rende, Italy.
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, Via Bucci 4C, 6C, 87036 Arcavacata di Rende, Italy; National Research Council (CNR), Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), via Amendola 122/O, 70126 Bari, Italy.
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19
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Yang W, Mei FC, Lin W, White MA, Li L, Li Y, Pan S, Cheng X. Protein SUMOylation promotes cAMP-independent EPAC1 activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.08.574738. [PMID: 38260470 PMCID: PMC10802480 DOI: 10.1101/2024.01.08.574738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Exchange protein directly activated by cAMP (EPAC1) mediates the intracellular functions of a critical stress-response second messenger, cAMP. Herein, we report that EPAC1 is a cellular substrate of protein SUMOylation, a prevalent stress-response posttranslational modification. Site-specific mapping of SUMOylation by mass spectrometer leads to identifying K561 as a primary SUMOylation site in EPAC1. Sequence and site-directed mutagenesis analyses reveal a functional SUMO-interacting motif required for cellular SUMOylation of EPAC1. SUMO modification of EPAC1 mediates its heat shock-induced Rap1/2 activation in a cAMP-independent manner. Structural modeling and molecular dynamics simulation studies demonstrate that SUMO substituent on K561 of EPAC1 promotes Rap1 interaction by increasing the buried surface area between the SUMOylated receptor and its effector. Our studies identify a functional SUMOylation site in EPAC1 and unveil a novel mechanism in which SUMOylation of EPAC1 leads to its autonomous activation. The findings of SUMOylation-mediated activation of EPAC1 not only provide new insights into our understanding of cellular regulation of EPAC1 but also will open up a new field of experimentation concerning the cross-talk between cAMP/EPAC1 signaling and protein SUMOylation, two major cellular stress response pathways, during cellular homeostasis.
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20
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Pándy-Szekeres G, Taracena Herrera LP, Caroli J, Kermani AA, Kulkarni Y, Keserű GM, Gloriam DE. GproteinDb in 2024: new G protein-GPCR couplings, AlphaFold2-multimer models and interface interactions. Nucleic Acids Res 2024; 52:D466-D475. [PMID: 38000391 PMCID: PMC10767870 DOI: 10.1093/nar/gkad1089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/26/2023] Open
Abstract
G proteins are the major signal proteins of ∼800 receptors for medicines, hormones, neurotransmitters, tastants and odorants. GproteinDb offers integrated genomic, structural, and pharmacological data and tools for analysis, visualization and experiment design. Here, we present the first major update of GproteinDb greatly expanding its coupling data and structural templates, adding AlphaFold2 structure models of GPCR-G protein complexes and advancing the interactive analysis tools for their interfaces underlying coupling selectivity. We present insights on coupling agreement across datasets and parameters, including constitutive activity, agonist-induced activity and kinetics. GproteinDb is accessible at https://gproteindb.org.
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Affiliation(s)
- Gáspár Pándy-Szekeres
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark
- Medicinal Chemistry Research Group, HUN-REN Research Center for Natural Sciences, Budapest H-1117, Hungary
| | - Luis P Taracena Herrera
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jimmy Caroli
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Ali A Kermani
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yashraj Kulkarni
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - György M Keserű
- Medicinal Chemistry Research Group, HUN-REN Research Center for Natural Sciences, Budapest H-1117, Hungary
| | - David E Gloriam
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark
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21
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Patel KN, Chavda D, Manna M. Molecular Docking of Intrinsically Disordered Proteins: Challenges and Strategies. Methods Mol Biol 2024; 2780:165-201. [PMID: 38987470 DOI: 10.1007/978-1-0716-3985-6_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Intrinsically disordered proteins (IDPs) are a novel class of proteins that have established a significant importance and attention within a very short period of time. These proteins are essentially characterized by their inherent structural disorder, encoded mainly by their amino acid sequences. The profound abundance of IDPs and intrinsically disordered regions (IDRs) in the biological world delineates their deep-rooted functionality. IDPs and IDRs convey such extensive functionality through their unique dynamic nature, which enables them to carry out huge number of multifaceted biomolecular interactions and make them "interaction hub" of the cellular systems. Additionally, with such widespread functions, their misfunctioning is also intimately associated with multiple diseases. Thus, understanding the dynamic heterogeneity of various IDPs along with their interactions with respective binding partners is an important field with immense potentials in biomolecular research. In this context, molecular docking-based computational approaches have proven to be remarkable in case of ordered proteins. Molecular docking methods essentially model the biomolecular interactions in both structural and energetic terms and use this information to characterize the putative interactions between the two participant molecules. However, direct applications of the conventional docking methods to study IDPs are largely limited by their structural heterogeneity and demands for unique IDP-centric strategies. Thus, in this chapter, we have presented an overview of current methodologies for successful docking operations involving IDPs and IDRs. These specialized methods majorly include the ensemble-based and fragment-based approaches with their own benefits and limitations. More recently, artificial intelligence and machine learning-assisted approaches are also used to significantly reduce the complexity and computational burden associated with various docking applications. Thus, this chapter aims to provide a comprehensive summary of major challenges and recent advancements of molecular docking approaches in the IDP field for their better utilization and greater applicability.Asp (D).
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Affiliation(s)
- Keyur N Patel
- Applied Phycology and Biotechnology Division, CSIR Central Salt and Marine Chemicals Research Institute, Bhavnagar, Gujarat, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Dhruvil Chavda
- Applied Phycology and Biotechnology Division, CSIR Central Salt and Marine Chemicals Research Institute, Bhavnagar, Gujarat, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Moutusi Manna
- Applied Phycology and Biotechnology Division, CSIR Central Salt and Marine Chemicals Research Institute, Bhavnagar, Gujarat, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India.
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Narsimulu B, Jakkula P, Qureshi R, Nasim F, Qureshi IA. Inhibition and structural insights of leishmanial glutamyl-tRNA synthetase for designing potent therapeutics. Int J Biol Macromol 2024; 254:127756. [PMID: 37907177 DOI: 10.1016/j.ijbiomac.2023.127756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/08/2023] [Accepted: 10/27/2023] [Indexed: 11/02/2023]
Abstract
Aminoacyl-tRNA synthetases (aaRSs), essential components of the protein synthesizing machinery, have been often chosen for devising therapeutics against parasitic diseases. Due to their relevance in drug development, the current study was designed to explore functional and structural aspects of Leishmania donovani glutamyl-tRNA synthetase (LdGluRS). Hence, LdGluRS was cloned into an expression vector and purified to homogeneity using chromatographic techniques. Purified protein showed maximum enzymatic activity at physiological pH, with more binding capacity towards its cofactor (Adenosine triphosphate, 0.06 ± 0.01 mM) than the cognate substrate (L-glutamate, 9.5 ± 0.5 mM). Remarkably, salicylate inhibited LdGluRS competitively with respect to L-glutamate and exhibited druglikeness with negligible effect on human macrophages. The protein possessed more α-helices (43 %) than β-sheets (12 %), whereas reductions in thermal stability and cofactor-binding affinity, along with variation in mode of inhibition after mutation signified the role of histidine (H60) as a catalytic residue. LdGluRS could also generate a pro-inflammatory milieu in human macrophages by upregulating cytokines. The docking study demonstrated the placement of salicylate into LdGluRS substrate-binding site, and the complex was found to be stable during molecular dynamics (MD) simulation. Altogether, our study highlights the understanding of molecular inhibition and structural features of glutamyl-tRNA synthetase from kinetoplastid parasites.
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Affiliation(s)
- Bandigi Narsimulu
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Prof. C.R. Rao Road, Hyderabad 500046, India
| | - Pranay Jakkula
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Prof. C.R. Rao Road, Hyderabad 500046, India
| | - Rahila Qureshi
- Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
| | - Fouzia Nasim
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Prof. C.R. Rao Road, Hyderabad 500046, India
| | - Insaf Ahmed Qureshi
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Prof. C.R. Rao Road, Hyderabad 500046, India.
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23
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York DM. Modern Alchemical Free Energy Methods for Drug Discovery Explained. ACS PHYSICAL CHEMISTRY AU 2023; 3:478-491. [PMID: 38034038 PMCID: PMC10683484 DOI: 10.1021/acsphyschemau.3c00033] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 12/02/2023]
Abstract
This Perspective provides a contextual explanation of the current state-of-the-art alchemical free energy methods and their role in drug discovery as well as highlights select emerging technologies. The narrative attempts to answer basic questions about what goes on "under the hood" in free energy simulations and provide general guidelines for how to run simulations and analyze the results. It is the hope that this work will provide a valuable introduction to students and scientists in the field.
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Affiliation(s)
- Darrin M. York
- Laboratory for Biomolecular
Simulation Research, Institute for Quantitative Biomedicine, and Department
of Chemistry and Chemical Biology, Rutgers
University, Piscataway, New Jersey 08854, United States
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24
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Zhang Z, Huang L, Zhang ZJ, Xu JH, Yu HL. Rational Design of Taxadiene Hydroxylase by Ancestral Enzyme Construction and the Elucidation of Key Amino Acids. Biochemistry 2023; 62:3214-3221. [PMID: 37902563 DOI: 10.1021/acs.biochem.3c00411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
Cytochrome P450 monooxygenases (CYP450s) play an important role in the biosynthesis of natural products by activating inert C-H bonds and inserting hydroxyl groups. However, the activities of most plant-derived CYP450s are extremely low, limiting the heterologous biosynthesis of natural products. Traditional enzyme engineering methods, either rational or screening-based, are not suitable for CYP450s because of the lack of crystal structures and high-throughput screening methods for this class of enzymes. CYP725A4 is the first hydroxylase involved in the biosynthesis pathway of Taxol. Its low activity, promiscuity, and multispecificity make it a bottleneck in Taxol biosynthesis. Here, we identified key amino acids that affect the in vivo activity of CYP725A4 by constructing the ancestral enzymes of CYP725A4. We obtained positive mutants that showed an improved yield of hydroxylated products based on the key amino acids identified, providing guidance for the modification of other CYP450s involved in the biosynthesis of natural products.
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Affiliation(s)
- Zihan Zhang
- State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Centre for Biomanufacturing, East China University of Science and Technology, Shanghai 200237, China
| | - Longhao Huang
- State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Centre for Biomanufacturing, East China University of Science and Technology, Shanghai 200237, China
| | - Zhi-Jun Zhang
- State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Centre for Biomanufacturing, East China University of Science and Technology, Shanghai 200237, China
| | - Jian-He Xu
- State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Centre for Biomanufacturing, East China University of Science and Technology, Shanghai 200237, China
| | - Hui-Lei Yu
- State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Centre for Biomanufacturing, East China University of Science and Technology, Shanghai 200237, China
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25
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Ahmad B, Lerma-Reyes R, Mukherjee T, Nguyen HV, Weber AL, Schulze WX, Comer JR, Schrick K. Nuclear localization of HD-Zip IV transcription factor GLABRA2 is driven by Importin α. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.03.565550. [PMID: 37961624 PMCID: PMC10635128 DOI: 10.1101/2023.11.03.565550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
GLABRA2 (GL2), a class IV homeodomain leucine-zipper (HD-Zip IV) transcription factor (TF) from Arabidopsis , is a developmental regulator of specialized cell types in the epidermis. GL2 contains a putative monopartite nuclear localization sequence (NLS) partially overlapping with its homeodomain (HD). We demonstrate that NLS deletion or alanine substitution of its basic residues (KRKRKK) affects nuclear localization and results in a loss-of-function phenotype. Fusion of the predicted NLS (GTNKRKRKKYHRH) to the fluorescent protein EYFP is sufficient for its nuclear localization in roots and trichomes. The functional NLS is evolutionarily conserved in a distinct subset of HD-Zip IV members including PROTODERMAL FACTOR2 (PDF2). Despite partial overlap of the NLS with the HD, genetic dissection of the NLS from PDF2 indicates that nuclear localization and DNA binding are separable functions. Affinity purification of GL2 from plant tissues followed by mass spectrometry-based proteomics identified Importin α (IMPα) isoforms as potential GL2 interactors. NLS structural prediction and molecular docking studies with IMPα-3 revealed major interacting residues. Split-ubiquitin cytosolic yeast two-hybrid assays suggest interaction between GL2 and four IMPα isoforms from Arabidopsis. Direct interactions were verified in vitro by co-immunoprecipitation with recombinant proteins. IMPα triple mutants ( impα- 1,2,3 ) exhibit defects in EYFP:GL2 nuclear localization in trichomes but not in roots, consistent with tissue-specific and redundant functions of IMPα isoforms in Arabidopsis . Taken together, our findings provide mechanistic evidence for IMPα-dependent nuclear localization of GL2 and other HD-Zip IV TFs in plants. One sentence summary GLABRA2, a representative HD-Zip IV transcription factor from Arabidopsis , contains an evolutionarily conserved monopartite nuclear localization sequence that is recognized by Importin α for translocation to the nucleus, a process that is necessary for cell-type differentiation of the epidermis.
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26
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Alanzi AR, Parvez MK, Alqahtani MJ, Al-Dosari MS. Deep-sea fungal metabolites as potential inhibitors of glucose-regulatory enzymes: In silico structure-activity analysis. Saudi Pharm J 2023; 31:101776. [PMID: 37868645 PMCID: PMC10587758 DOI: 10.1016/j.jsps.2023.101776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/28/2023] [Indexed: 10/24/2023] Open
Abstract
Chronic diabetes mellites related hyperglycemia is a major cause of mortality and morbidity due to further complications like retinopathy, hypertension and cardiovascular diseases. Though several synthetic anti-diabetes drugs specifically targeting glucose-metabolism enzymes are available, they have their own limitations, including adverse side-effects. Unlike other natural or marine-derived pharmacologically important molecules, deep-sea fungi metabolites still remain under-explored for their anti-diabetes potential. We performed structure-based virtual screening of deep-sea fungal compounds selected by their physiochemical properties, targeting crucial enzymes viz., α -amylase, α -glucosidase, pancreatic-lipoprotein lipase, hexokinase-II and protein tyrosine phosphatase-1B involved in glucose-metabolism pathway. Following molecular docking scores and MD simulation analyses, the selected top ten compounds for each enzyme, were subjected to pharmacokinetics prediction based on their AdmetSAR- and pharmacophore-based features. Of these, cladosporol C, tenellone F, ozazino-cyclo-(2,3-dihydroxyl-trp-tyr), penicillactam and circumdatin G were identified as potential inhibitors of α -amylase, α -glucosidase, pancreatic-lipoprotein lipase, hexokinase-II and protein tyrosine phosphatase-1B, respectively. Our in silico data therefore, warrants further experimental and pharmacological studies to validate their anti-diabetes therapeutic potential.
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Affiliation(s)
- Abdullah R. Alanzi
- Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mohammad K. Parvez
- Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Moneerah J. Alqahtani
- Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mohammed S. Al-Dosari
- Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
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27
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Rahmati S, Bagherzadeh K, Arab SS, Torkashvand F, Amanlou M, Vaziri B. Computational designing of the ligands of Protein L affinity chromatography based on molecular docking and molecular dynamics simulations. J Biomol Struct Dyn 2023:1-11. [PMID: 37855377 DOI: 10.1080/07391102.2023.2268219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 09/29/2023] [Indexed: 10/20/2023]
Abstract
Protein L is a multidomain protein from Peptostreptococcus magnus with binding affinity to kappa light chain of human immunoglobulin (Ig) which is used for the purification of antibody fragments by affinity chromatography. The advances in protein engineering and computational biology approaches lead to the development of engineered affinity ligands with improved properties including binding affinity. In this study, molecular dynamics simulations (MDs) and Osprey software were used to design single B domains of the Protein L with higher affinity to antibody fragments. The modified B domains were then polymerized to ligand with six B domains by homology modeling methods. The results showed that single B domain mutants of MB1 (Thr865Trp) and MB2 (Thr847Met-Thr865Trp) had higher binding affinity to Fab compared to the wild single B domain. Also, MDs and molecular docking results showed that the polymerized Proteins L including the wild and mutated six B domains (6B0, 6B1, and 6B2) were stable during MDs and the two mutants of 6B1 and 6B2 showed higher binding affinity to Fab relative to the wild type.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Saman Rahmati
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Kowsar Bagherzadeh
- Stem Cell and Regenerative Medicine Research Center, Iran University of Medical Sciences, Tehran, Iran
- Eye Research Center, The Five Senses Health Institute, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Seyed Shahriar Arab
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | | | - Massoud Amanlou
- Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Behrouz Vaziri
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
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28
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Schütz M, Wangen C, Sommerer M, Kögler M, Eickhoff J, Degenhart C, Klebl B, Naing Z, Egilmezer E, Hamilton ST, Rawlinson WD, Sticht H, Marschall M. Cytomegalovirus cyclin-dependent kinase ortholog vCDK/pUL97 undergoes regulatory interaction with human cyclin H and CDK7 to codetermine viral replication efficiency. Virus Res 2023; 335:199200. [PMID: 37591314 PMCID: PMC10445456 DOI: 10.1016/j.virusres.2023.199200] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 08/19/2023]
Abstract
Human cytomegalovirus (HCMV) infection is shaped by a tightly regulated interplay between viral and cellular proteins. Distinct kinase activities, such as the viral cyclin-dependent kinase ortholog (vCDK) pUL97 and cellular CDK7 are both crucial for efficient viral replication. Previously, we reported that both kinases, vCDK/pUL97 and CDK7, interact with cyclin H, thereby achieving an enhanced level of kinase activity and overall functionality in viral replication. Here we provide a variety of novel results, as generated on a methodologically extended basis, and present a concept for the codetermination of viral replication efficiency through these kinase activities: (i) cyclin H expression, in various human cell types, is substantially upregulated by strains of HCMV including the clinically relevant HCMV Merlin; (ii) vCDK/pUL97 interacts with human cyclin H in both HCMV-infected and plasmid-transfected cell systems; (iii) a doxycycline-inducible shRNA-dependent knock-down (KD) of cyclin H significantly reduces pUL97 activity (qSox in vitro kinase assay); (iv) accordingly, pUL97 in vitro kinase activity is seen significantly increased upon addition of recombinant cyclin H; (v) as a point of specific importance, human CDK7 activity shows an increase by vCDK/pUL97-mediated trans-stimulation (whereas pUL97 is not stimulated by CDK7); (vi) phosphosite-specific antibodies indicate an upregulated CDK7 phosphorylation upon HCMV infection, as mediated through a pUL97-specific modulatory effect (i.e. shown by pUL97 inhibitor treatment or pUL97-deficient viral mutant); (vii) finally, an efficient KD of cyclin H in primary fibroblasts generally results in an impaired HCMV replication efficiency as measured on protein and genomic levels. These results show evidence for the codetermination of viral replication by vCDK/pUL97, cyclin H and CDK7, thus supporting the specific importance of cyclin H as a central regulatory factor, and suggesting novel targeting options for antiviral drugs.
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Affiliation(s)
- Martin Schütz
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, Erlangen 91054, Germany.
| | - Christina Wangen
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, Erlangen 91054, Germany
| | - Mona Sommerer
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, Erlangen 91054, Germany
| | - Melanie Kögler
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, Erlangen 91054, Germany
| | | | | | - Bert Klebl
- Lead Discovery Center GmbH, Dortmund, Germany
| | - Zin Naing
- Serology and Virology Division, NSW Health Pathology Microbiology, Prince of Wales Hospital, and Schools of Women's and Children's Health, Medicine and Biotechnology and Biomolecular Sciences, University of New South Wales, High Street, Sydney, Australia
| | - Ece Egilmezer
- Serology and Virology Division, NSW Health Pathology Microbiology, Prince of Wales Hospital, and Schools of Women's and Children's Health, Medicine and Biotechnology and Biomolecular Sciences, University of New South Wales, High Street, Sydney, Australia
| | - Stuart T Hamilton
- Serology and Virology Division, NSW Health Pathology Microbiology, Prince of Wales Hospital, and Schools of Women's and Children's Health, Medicine and Biotechnology and Biomolecular Sciences, University of New South Wales, High Street, Sydney, Australia
| | - William D Rawlinson
- Serology and Virology Division, NSW Health Pathology Microbiology, Prince of Wales Hospital, and Schools of Women's and Children's Health, Medicine and Biotechnology and Biomolecular Sciences, University of New South Wales, High Street, Sydney, Australia
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, FAU, Erlangen, Germany
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 4, Erlangen 91054, Germany.
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29
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Lever R, Simmons E, Gamble-Milner R, Buckley R, Harrison C, Parkes A, Mitchell L, Gausden J, Škulj S, Bertoša B, Bolt E, Allers T. Archaeal Hel308 suppresses recombination through a catalytic switch that controls DNA annealing. Nucleic Acids Res 2023; 51:8563-8574. [PMID: 37409572 PMCID: PMC10484726 DOI: 10.1093/nar/gkad572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 06/14/2023] [Accepted: 06/23/2023] [Indexed: 07/07/2023] Open
Abstract
Hel308 helicases promote genome stability in archaea and are conserved in metazoans, where they are known as HELQ. Their helicase mechanism is well characterised, but it is unclear how they specifically contribute to genome stability in archaea. We show here that a highly conserved motif of Hel308/HELQ helicases (motif IVa, F/YHHAGL) modulates both DNA unwinding and a newly identified strand annealing function of archaeal Hel308. A single amino acid substitution in motif IVa results in hyper-active DNA helicase and annealase activities of purified Hel308 in vitro. All-atom molecular dynamics simulations using Hel308 crystal structures provided a molecular basis for these differences between mutant and wild type Hel308. In archaeal cells, the same mutation results in 160000-fold increased recombination, exclusively as gene conversion (non-crossover) events. However, crossover recombination is unaffected by the motif IVa mutation, as is cell viability or DNA damage sensitivity. By contrast, cells lacking Hel308 show impaired growth, increased sensitivity to DNA cross-linking agents, and only moderately increased recombination. Our data reveal that archaeal Hel308 suppresses recombination and promotes DNA repair, and that motif IVa in the RecA2 domain acts as a catalytic switch to modulate the separable recombination and repair activities of Hel308.
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Affiliation(s)
- Rebecca J Lever
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Emily Simmons
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | | | - Ryan J Buckley
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Catherine Harrison
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Ashley J Parkes
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Laura Mitchell
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Jacob A Gausden
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Sanja Škulj
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
| | - Branimir Bertoša
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
| | - Edward L Bolt
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
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30
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Han R, Yoon H, Kim G, Lee H, Lee Y. Revolutionizing Medicinal Chemistry: The Application of Artificial Intelligence (AI) in Early Drug Discovery. Pharmaceuticals (Basel) 2023; 16:1259. [PMID: 37765069 PMCID: PMC10537003 DOI: 10.3390/ph16091259] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/24/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Artificial intelligence (AI) has permeated various sectors, including the pharmaceutical industry and research, where it has been utilized to efficiently identify new chemical entities with desirable properties. The application of AI algorithms to drug discovery presents both remarkable opportunities and challenges. This review article focuses on the transformative role of AI in medicinal chemistry. We delve into the applications of machine learning and deep learning techniques in drug screening and design, discussing their potential to expedite the early drug discovery process. In particular, we provide a comprehensive overview of the use of AI algorithms in predicting protein structures, drug-target interactions, and molecular properties such as drug toxicity. While AI has accelerated the drug discovery process, data quality issues and technological constraints remain challenges. Nonetheless, new relationships and methods have been unveiled, demonstrating AI's expanding potential in predicting and understanding drug interactions and properties. For its full potential to be realized, interdisciplinary collaboration is essential. This review underscores AI's growing influence on the future trajectory of medicinal chemistry and stresses the importance of ongoing synergies between computational and domain experts.
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Affiliation(s)
| | | | | | | | - Yoonji Lee
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
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31
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Le Naour—Vernet M, Charriat F, Gracy J, Cros-Arteil S, Ravel S, Veillet F, Meusnier I, Padilla A, Kroj T, Cesari S, Gladieux P. Adaptive evolution in virulence effectors of the rice blast fungus Pyricularia oryzae. PLoS Pathog 2023; 19:e1011294. [PMID: 37695773 PMCID: PMC10513199 DOI: 10.1371/journal.ppat.1011294] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 09/21/2023] [Accepted: 08/09/2023] [Indexed: 09/13/2023] Open
Abstract
Plant pathogens secrete proteins called effectors that target host cellular processes to promote disease. Recently, structural genomics has identified several families of fungal effectors that share a similar three-dimensional structure despite remarkably variable amino-acid sequences and surface properties. To explore the selective forces that underlie the sequence variability of structurally-analogous effectors, we focused on MAX effectors, a structural family of effectors that are major determinants of virulence in the rice blast fungus Pyricularia oryzae. Using structure-informed gene annotation, we identified 58 to 78 MAX effector genes per genome in a set of 120 isolates representing seven host-associated lineages. The expression of MAX effector genes was primarily restricted to the early biotrophic phase of infection and strongly influenced by the host plant. Pangenome analyses of MAX effectors demonstrated extensive presence/absence polymorphism and identified gene loss events possibly involved in host range adaptation. However, gene knock-in experiments did not reveal a strong effect on virulence phenotypes suggesting that other evolutionary mechanisms are the main drivers of MAX effector losses. MAX effectors displayed high levels of standing variation and high rates of non-synonymous substitutions, pointing to widespread positive selection shaping the molecular diversity of MAX effectors. The combination of these analyses with structural data revealed that positive selection acts mostly on residues located in particular structural elements and at specific positions. By providing a comprehensive catalog of amino acid polymorphism, and by identifying the structural determinants of the sequence diversity, our work will inform future studies aimed at elucidating the function and mode of action of MAX effectors.
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Affiliation(s)
- Marie Le Naour—Vernet
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Florian Charriat
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Jérôme Gracy
- Centre de Biologie Structurale (CBS), Univ Montpellier, INSERM, CNRS, Montpellier, France
| | - Sandrine Cros-Arteil
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Sébastien Ravel
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
- CIRAD, UMR PHIM, Montpellier, France
| | - Florian Veillet
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Isabelle Meusnier
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - André Padilla
- Centre de Biologie Structurale (CBS), Univ Montpellier, INSERM, CNRS, Montpellier, France
| | - Thomas Kroj
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Stella Cesari
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Pierre Gladieux
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
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32
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Miller AP, O'Neill SE, Lampi KJ, Reichow SL. The α-crystallin chaperones undergo a quasi-ordered co-aggregation process in response to saturating client interaction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.15.553435. [PMID: 37645910 PMCID: PMC10462102 DOI: 10.1101/2023.08.15.553435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Small heat shock proteins (sHSPs) are ATP-independent chaperones vital to cellular proteostasis, preventing protein aggregation events linked to various human diseases including cataract. The α-crystallins, αA-crystallin (αAc) and αB-crystallin (αBc), represent archetypal sHSPs that exhibit complex polydispersed oligomeric assemblies and rapid subunit exchange dynamics. Yet, our understanding of how this plasticity contributes to chaperone function remains poorly understood. This study investigates structural changes in αAc and αBc during client sequestration under varying degree of chaperone saturation. Using biochemical and biophysical analyses combined with single-particle electron microscopy (EM), we examined αAc and αBc in their apo-states and at various stages of client-induced co-aggregation, using lysozyme as a model client. Quantitative single-particle analysis unveiled a continuous spectrum of oligomeric states formed during the co-aggregation process, marked by significant client-triggered expansion and quasi-ordered elongation of the sHSP scaffold. These structural modifications culminated in an apparent amorphous collapse of chaperone-client complexes, resulting in the creation of co-aggregates capable of scattering visible light. Intriguingly, these co-aggregates maintain internal morphological features of highly elongated sHSP scaffolding with striking resemblance to polymeric α-crystallin species isolated from aged lens tissue. This mechanism appears consistent across both αAc and αBc, albeit with varying degrees of susceptibility to client-induced co-aggregation. Importantly, our findings suggest that client-induced co-aggregation follows a distinctive mechanistic and quasi-ordered trajectory, distinct from a purely amorphous process. These insights reshape our understanding of the physiological and pathophysiological co-aggregation processes of sHSPs, carrying potential implications for a pathway toward cataract formation.
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Affiliation(s)
- Adam P Miller
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, USA
- Vollum Institute, Oregon Health & Science University, Portland, Oregon 97239, USA
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
| | - Susan E O'Neill
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
| | - Kirsten J Lampi
- Integrative Biosciences, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Steve L Reichow
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, USA
- Vollum Institute, Oregon Health & Science University, Portland, Oregon 97239, USA
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
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Ferreira I, Oliveira I, Bordon K, Reis M, Wiezel G, Sanchez C, Santos L, Santos-Filho N, Pucca M, Antunes L, Lopes D, Arantes E. Beyond Angiogenesis: The Multitasking Approach of the First PEGylated Vascular Endothelial Growth Factor ( CdtVEGF) from Brazilian Rattlesnake Venom. Toxins (Basel) 2023; 15:483. [PMID: 37624240 PMCID: PMC10467076 DOI: 10.3390/toxins15080483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/27/2023] [Accepted: 07/28/2023] [Indexed: 08/26/2023] Open
Abstract
A pioneering study regarding the isolation, biochemical evaluation, functional assays and first PEGylation report of a novel vascular endothelial growth factor from Crotalus durissus terrificus venom (CdtVEGF and PEG-CdtVEGF). CdtVEGF was isolated from crude venom using two different chromatographic steps, representing 2% of soluble venom proteins. Its primary sequence was determined using mass spectrometry analysis, and the molecule demonstrated no affinity to heparin. The Brazilian crotalid antivenom recognized CdtVEGF. Both native and PEGylated CdtVEGF were able to induce new vessel formation and migration, and to increase the metabolic activity of human umbilical endothelial vascular cells (HUVEC), resulting in better wound closure (~50% within 12 h) using the native form. CdtVEGF induced leukocyte recruitment to the peritoneal cavity in mice, with a predominance of neutrophil influx followed by lymphocytes, demonstrating the ability to activate the immune system. The molecule also induced a dose-dependent increase in vascular permeability, and PEG-CdtVEGF showed less in vivo inflammatory activity than CdtVEGF. By unraveling the intricate properties of minor components of snake venom like svVEGF, this study illuminates the indispensable significance of exploring these molecular tools to unveil physiological and pathological processes, elucidates the mechanisms of snakebite envenomings, and could possibly be used to design a therapeutic drug.
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Affiliation(s)
- Isabela Ferreira
- Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of Sao Paulo, Ribeirao Preto 14040-903, SP, Brazil
| | - Isadora Oliveira
- Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of Sao Paulo, Ribeirao Preto 14040-903, SP, Brazil
| | - Karla Bordon
- Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of Sao Paulo, Ribeirao Preto 14040-903, SP, Brazil
| | - Mouzarllem Reis
- Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of Sao Paulo, Ribeirao Preto 14040-903, SP, Brazil
| | - Gisele Wiezel
- Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of Sao Paulo, Ribeirao Preto 14040-903, SP, Brazil
| | - Caroline Sanchez
- Department of Clinical Analysis, Toxicology and Food Science, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto 14040-903, SP, Brazil
| | - Luísa Santos
- Institute Multidisciplinary in Health, Federal University of Bahia, Vitoria da Conquista 40110-909, BA, Brazil
| | - Norival Santos-Filho
- Department of Biochemistry and Organic Chemistry, Chemistry Institute, Sao Paulo State University (UNESP), Araraquara 14800-901, SP, Brazil
| | - Manuela Pucca
- Department of Clinical Analysis, Sao Paulo State University (UNESP) Araraquara 14800-901, SP, Brazil
| | - Lusânia Antunes
- Department of Clinical Analysis, Toxicology and Food Science, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto 14040-903, SP, Brazil
| | - Daiana Lopes
- Institute Multidisciplinary in Health, Federal University of Bahia, Vitoria da Conquista 40110-909, BA, Brazil
| | - Eliane Arantes
- Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of Sao Paulo, Ribeirao Preto 14040-903, SP, Brazil
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de Freitas Fernandes A, Leonardo DA, Cavini IA, Rosa HVD, Vargas JA, D'Muniz Pereira H, Nascimento AS, Garratt RC. Conservation and divergence of the G-interfaces of Drosophila melanogaster septins. Cytoskeleton (Hoboken) 2023; 80:153-168. [PMID: 36576069 DOI: 10.1002/cm.21740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 12/19/2022] [Accepted: 12/26/2022] [Indexed: 12/29/2022]
Abstract
Septins possess a conserved guanine nucleotide-binding (G) domain that participates in the stabilization of organized hetero-oligomeric complexes which assemble into filaments, rings and network-like structures. The fruit fly, Drosophila melanogaster, has five such septin genes encoding Sep1, Sep2, Sep4, Sep5 and Pnut. Here, we report the crystal structure of the heterodimer formed between the G-domains of Sep1 and Sep2, the first from an insect to be described to date. A G-interface stabilizes the dimer (in agreement with the expected arrangement for the Drosophila hexameric particle) and this bears significant resemblance to its human counterparts, even down to the level of individual amino acid interactions. On the other hand, a model for the G-interface formed between the two copies of Pnut which occupy the centre of the hexamer, shows important structural differences, including the loss of a highly favourable bifurcated salt-bridge network. Whereas wild-type Pnut purifies as a monomer, the reintroduction of the salt-bridge network results in stabilizing the dimeric interface in solution as shown by size exclusion chromatography and thermal stability measurements. Adaptive steered molecular dynamics reveals an unzipping mechanism for dimer dissociation which initiates at a point of electrostatic repulsion within the switch II region. Overall, the data contribute to a better understanding of the molecular interactions involved in septin assembly/disassembly.
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Affiliation(s)
| | | | | | | | - Jhon Antoni Vargas
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
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Szal T, Chauhan SS, Lewe P, Rachad FZ, Madre M, Paunina L, Witt S, Parthasarathi R, Windshügel B. Efflux Pump-Binding 4(3-Aminocyclobutyl)Pyrimidin-2-Amines Are Colloidal Aggregators. Biomolecules 2023; 13:1000. [PMID: 37371580 DOI: 10.3390/biom13061000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/02/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
Efflux pumps are a relevant factor in antimicrobial resistance. In E. coli, the tripartite efflux pump AcrAB-TolC removes a chemically diverse set of antibiotics from the bacterium. Therefore, small molecules interfering with efflux pump function are considered adjuvants for improving antimicrobial therapies. Several compounds targeting the periplasmic adapter protein AcrA and the efflux pump AcrB have been identified to act synergistically with different antibiotics. Among those, several 4(3-aminocyclobutyl)pyrimidin-2-amines have been shown to bind to both proteins. In this study, we intended to identify analogs of these substances with improved binding affinity to AcrA using virtual screening followed by experimental validation. While we succeeded in identifying several compounds showing a synergistic effect with erythromycin on E. coli, biophysical studies suggested that 4(3-aminocyclobutyl)pyrimidin-2-amines form colloidal aggregates that do not bind specifically to AcrA. Therefore, these substances are not suited for further development. Our study emphasizes the importance of implementing additional control experiments to identify aggregators among bioactive compounds.
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Affiliation(s)
- Tania Szal
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Discovery Research ScreeningPort, 22525 Hamburg, Germany
- School of Science, Constructor University, 28759 Bremen, Germany
| | - Shweta Singh Chauhan
- Computational Toxicology Facility, Toxicoinformatics & Industrial Research CSIR-Indian Institute of Toxicology Research, Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow 226001, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Philipp Lewe
- Centre for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE), 22607 Hamburg, Germany
| | - Fatima-Zahra Rachad
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Discovery Research ScreeningPort, 22525 Hamburg, Germany
| | - Marina Madre
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia
| | - Laura Paunina
- Latvian Institute of Organic Synthesis, LV-1006 Riga, Latvia
| | - Susanne Witt
- Centre for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE), 22607 Hamburg, Germany
| | - Ramakrishnan Parthasarathi
- Computational Toxicology Facility, Toxicoinformatics & Industrial Research CSIR-Indian Institute of Toxicology Research, Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow 226001, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Björn Windshügel
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Discovery Research ScreeningPort, 22525 Hamburg, Germany
- School of Science, Constructor University, 28759 Bremen, Germany
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36
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Di Ianni A, Tüting C, Kipping M, Ihling CH, Köppen J, Iacobucci C, Arlt C, Kastritis PL, Sinz A. Structural assessment of the full-length wild-type tumor suppressor protein p53 by mass spectrometry-guided computational modeling. Sci Rep 2023; 13:8497. [PMID: 37231156 DOI: 10.1038/s41598-023-35437-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 05/18/2023] [Indexed: 05/27/2023] Open
Abstract
The tetrameric tumor suppressor p53 represents a great challenge for 3D-structural analysis due to its high degree of intrinsic disorder (ca. 40%). We aim to shed light on the structural and functional roles of p53's C-terminal region in full-length, wild-type human p53 tetramer and their importance for DNA binding. For this, we employed complementary techniques of structural mass spectrometry (MS) in an integrated approach with computational modeling. Our results show no major conformational differences in p53 between DNA-bound and DNA-free states, but reveal a substantial compaction of p53's C-terminal region. This supports the proposed mechanism of unspecific DNA binding to the C-terminal region of p53 prior to transcription initiation by specific DNA binding to the core domain of p53. The synergies between complementary structural MS techniques and computational modeling as pursued in our integrative approach is envisioned to serve as general strategy for studying intrinsically disordered proteins (IDPs) and intrinsically disordered region (IDRs).
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Affiliation(s)
- Alessio Di Ianni
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
- Center for Structural Mass Spectrometry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
| | - Christian Tüting
- ZIK HALOmem and Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany
| | - Marc Kipping
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
- Center for Structural Mass Spectrometry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
| | - Christian H Ihling
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
- Center for Structural Mass Spectrometry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
| | - Janett Köppen
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
- Center for Structural Mass Spectrometry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
| | - Claudio Iacobucci
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
- Center for Structural Mass Spectrometry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany
- Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, Coppito, 67100, L'Aquila, Italy
| | - Christian Arlt
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany.
- Center for Structural Mass Spectrometry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany.
| | - Panagiotis L Kastritis
- ZIK HALOmem and Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany
| | - Andrea Sinz
- Department of Pharmaceutical Chemistry and Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany.
- Center for Structural Mass Spectrometry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 01620, Halle (Saale), Germany.
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Casas-Sanchez A, Ramaswamy R, Perally S, Haines LR, Rose C, Aguilera-Flores M, Portillo S, Verbeelen M, Hussain S, Smithson L, Yunta C, Lehane MJ, Vaughan S, van den Abbeele J, Almeida IC, Boulanger MJ, Acosta-Serrano Á. The Trypanosoma brucei MISP family of invariant proteins is co-expressed with BARP as triple helical bundle structures on the surface of salivary gland forms, but is dispensable for parasite development within the tsetse vector. PLoS Pathog 2023; 19:e1011269. [PMID: 36996244 PMCID: PMC10089363 DOI: 10.1371/journal.ppat.1011269] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 04/11/2023] [Accepted: 03/08/2023] [Indexed: 04/01/2023] Open
Abstract
Trypanosoma brucei spp. develop into mammalian-infectious metacyclic trypomastigotes inside tsetse salivary glands. Besides acquiring a variant surface glycoprotein (VSG) coat, little is known about the metacyclic expression of invariant surface antigens. Proteomic analyses of saliva from T. brucei-infected tsetse flies identified, in addition to VSG and Brucei Alanine-Rich Protein (BARP) peptides, a family of glycosylphosphatidylinositol (GPI)-anchored surface proteins herein named as Metacyclic Invariant Surface Proteins (MISP) because of its predominant expression on the surface of metacyclic trypomastigotes. The MISP family is encoded by five paralog genes with >80% protein identity, which are exclusively expressed by salivary gland stages of the parasite and peak in metacyclic stage, as shown by confocal microscopy and immuno-high resolution scanning electron microscopy. Crystallographic analysis of a MISP isoform (MISP360) and a high confidence model of BARP revealed a triple helical bundle architecture commonly found in other trypanosome surface proteins. Molecular modelling combined with live fluorescent microscopy suggests that MISP N-termini are potentially extended above the metacyclic VSG coat, and thus could be tested as a transmission-blocking vaccine target. However, vaccination with recombinant MISP360 isoform did not protect mice against a T. brucei infectious tsetse bite. Lastly, both CRISPR-Cas9-driven knock out and RNAi knock down of all MISP paralogues suggest they are not essential for parasite development in the tsetse vector. We suggest MISP may be relevant during trypanosome transmission or establishment in the vertebrate's skin.
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Affiliation(s)
- Aitor Casas-Sanchez
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | | | - Samïrah Perally
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Lee R. Haines
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Clair Rose
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Marcela Aguilera-Flores
- Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Susana Portillo
- Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | | | | | - Laura Smithson
- Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
| | - Cristina Yunta
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Michael J. Lehane
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Sue Vaughan
- Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
| | | | - Igor C. Almeida
- Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Martin J. Boulanger
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, Canada
| | - Álvaro Acosta-Serrano
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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Insights into the Transport Cycle of LAT1 and Interaction with the Inhibitor JPH203. Int J Mol Sci 2023; 24:ijms24044042. [PMID: 36835453 PMCID: PMC9965313 DOI: 10.3390/ijms24044042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/08/2023] [Accepted: 02/15/2023] [Indexed: 02/19/2023] Open
Abstract
The large Amino Acid Transporter 1 (LAT1) is an interesting target in drug discovery since this transporter is overexpressed in several human cancers. Furthermore, due to its location in the blood-brain barrier (BBB), LAT1 is interesting for delivering pro-drugs to the brain. In this work, we focused on defining the transport cycle of LAT1 using an in silico approach. So far, studies of the interaction of LAT1 with substrates and inhibitors have not considered that the transporter must undergo at least four different conformations to complete the transport cycle. We built outward-open and inward-occluded conformations of LAT1 using an optimized homology modelling procedure. We used these 3D models and the cryo-EM structures in outward-occluded and inward-open conformations to define the substrate/protein interaction during the transport cycle. We found that the binding scores for the substrate depend on the conformation, with the occluded states as the crucial steps affecting the substrate affinity. Finally, we analyzed the interaction of JPH203, a high-affinity inhibitor of LAT1. The results indicate that conformational states must be considered for in silico analyses and early-stage drug discovery. The two built models, together with the available cryo-EM 3D structures, provide important information on the LAT1 transport cycle, which could be used to speed up the identification of potential inhibitors through in silico screening.
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Yu J, Ge J, Yu H, Ye L. Improved Bioproduction of the Nylon 12 Monomer by Combining the Directed Evolution of P450 and Enhancing Heme Synthesis. Molecules 2023; 28:molecules28041758. [PMID: 36838746 PMCID: PMC9963201 DOI: 10.3390/molecules28041758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/04/2023] [Accepted: 02/08/2023] [Indexed: 02/15/2023] Open
Abstract
The nylon 12 (PA12) monomer ω-aminododecanoic acid (ω-AmDDA) could be synthesized from lauric acid (DDA) through multi-enzyme cascade transformation using engineered E. coli, with the P450 catalyzing terminal hydroxylation of DDA as a rate-limiting enzyme. Its activity is jointly determined by the heme domain and the reductase domain. To obtain a P450 mutant with higher activity, directed evolution was conducted using a colorimetric high-throughput screening (HTS) system with DDA as the real substrate. After two rounds of directed evolution, a positive double-site mutant (R14R/D629G) with 90.3% higher activity was obtained. Molecular docking analysis, kinetic parameter determination and protein electrophoresis suggested the improved soluble expression of P450 resulting from the synonymous mutation near the N-terminus and the shortened distance of the electron transfer between FMN and FAD caused by D629G mutation as the major reasons for activity improvement. The significantly increased kcat and unchanged Km provided further evidence for the increase in electron transfer efficiency. Considering the important role of heme in P450, its supply was strengthened by the metabolic engineering of the heme synthesis pathway. By combining P450-directed evolution and enhancing heme synthesis, 2.02 ± 0.03 g/L of ω-AmDDA was produced from 10 mM DDA, with a yield of 93.6%.
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Affiliation(s)
- Jiaming Yu
- Key Laboratory of Biomass Chemical Engineering (Education Ministry), College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
| | - Jiawei Ge
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
| | - Hongwei Yu
- Key Laboratory of Biomass Chemical Engineering (Education Ministry), College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
- Correspondence: (H.Y.); (L.Y.)
| | - Lidan Ye
- Key Laboratory of Biomass Chemical Engineering (Education Ministry), College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
- Correspondence: (H.Y.); (L.Y.)
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40
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Tvaroška I, Kozmon S, Kóňa J. Molecular Modeling Insights into the Structure and Behavior of Integrins: A Review. Cells 2023; 12:cells12020324. [PMID: 36672259 PMCID: PMC9856412 DOI: 10.3390/cells12020324] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/09/2023] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Integrins are heterodimeric glycoproteins crucial to the physiology and pathology of many biological functions. As adhesion molecules, they mediate immune cell trafficking, migration, and immunological synapse formation during inflammation and cancer. The recognition of the vital roles of integrins in various diseases revealed their therapeutic potential. Despite the great effort in the last thirty years, up to now, only seven integrin-based drugs have entered the market. Recent progress in deciphering integrin functions, signaling, and interactions with ligands, along with advancement in rational drug design strategies, provide an opportunity to exploit their therapeutic potential and discover novel agents. This review will discuss the molecular modeling methods used in determining integrins' dynamic properties and in providing information toward understanding their properties and function at the atomic level. Then, we will survey the relevant contributions and the current understanding of integrin structure, activation, the binding of essential ligands, and the role of molecular modeling methods in the rational design of antagonists. We will emphasize the role played by molecular modeling methods in progress in these areas and the designing of integrin antagonists.
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Affiliation(s)
- Igor Tvaroška
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, 845 38 Bratislava, Slovakia
- Correspondence:
| | - Stanislav Kozmon
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, 845 38 Bratislava, Slovakia
- Medical Vision o. z., Záhradnícka 4837/55, 821 08 Bratislava, Slovakia
| | - Juraj Kóňa
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, 845 38 Bratislava, Slovakia
- Medical Vision o. z., Záhradnícka 4837/55, 821 08 Bratislava, Slovakia
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41
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Baltoumas FA, Karatzas E, Paez-Espino D, Venetsianou NK, Aplakidou E, Oulas A, Finn RD, Ovchinnikov S, Pafilis E, Kyrpides NC, Pavlopoulos GA. Exploring microbial functional biodiversity at the protein family level-From metagenomic sequence reads to annotated protein clusters. FRONTIERS IN BIOINFORMATICS 2023; 3:1157956. [PMID: 36959975 PMCID: PMC10029925 DOI: 10.3389/fbinf.2023.1157956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
Metagenomics has enabled accessing the genetic repertoire of natural microbial communities. Metagenome shotgun sequencing has become the method of choice for studying and classifying microorganisms from various environments. To this end, several methods have been developed to process and analyze the sequence data from raw reads to end-products such as predicted protein sequences or families. In this article, we provide a thorough review to simplify such processes and discuss the alternative methodologies that can be followed in order to explore biodiversity at the protein family level. We provide details for analysis tools and we comment on their scalability as well as their advantages and disadvantages. Finally, we report the available data repositories and recommend various approaches for protein family annotation related to phylogenetic distribution, structure prediction and metadata enrichment.
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Affiliation(s)
- Fotis A. Baltoumas
- Institute for Fundamental Biomedical Research, BSRC “Alexander Fleming”, Vari, Greece
- *Correspondence: Fotis A. Baltoumas, ; Nikos C. Kyrpides, ; Georgios A. Pavlopoulos,
| | - Evangelos Karatzas
- Institute for Fundamental Biomedical Research, BSRC “Alexander Fleming”, Vari, Greece
| | - David Paez-Espino
- Lawrence Berkeley National Laboratory, DOE Joint Genome Institute, Berkeley, CA, United States
| | - Nefeli K. Venetsianou
- Institute for Fundamental Biomedical Research, BSRC “Alexander Fleming”, Vari, Greece
| | - Eleni Aplakidou
- Institute for Fundamental Biomedical Research, BSRC “Alexander Fleming”, Vari, Greece
| | - Anastasis Oulas
- The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Robert D. Finn
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, United Kingdom
| | - Sergey Ovchinnikov
- John Harvard Distinguished Science Fellowship Program, Harvard University, Cambridge, MA, United States
| | - Evangelos Pafilis
- Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC), Hellenic Centre for Marine Research (HCMR), Heraklion, Greece
| | - Nikos C. Kyrpides
- Lawrence Berkeley National Laboratory, DOE Joint Genome Institute, Berkeley, CA, United States
- *Correspondence: Fotis A. Baltoumas, ; Nikos C. Kyrpides, ; Georgios A. Pavlopoulos,
| | - Georgios A. Pavlopoulos
- Institute for Fundamental Biomedical Research, BSRC “Alexander Fleming”, Vari, Greece
- Center of New Biotechnologies and Precision Medicine, Department of Medicine, School of Health Sciences, National and Kapodistrian University of Athens, Athens, Greece
- Hellenic Army Academy, Vari, Greece
- *Correspondence: Fotis A. Baltoumas, ; Nikos C. Kyrpides, ; Georgios A. Pavlopoulos,
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42
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Perry-Hauser NA, VanDyck MW, Lee KH, Shi L, Javitch JA. Disentangling autoproteolytic cleavage from tethered agonist-dependent activation of the adhesion receptor ADGRL3. J Biol Chem 2022; 298:102594. [PMID: 36244455 PMCID: PMC9674912 DOI: 10.1016/j.jbc.2022.102594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/07/2022] [Accepted: 10/10/2022] [Indexed: 11/07/2022] Open
Abstract
Adhesion G protein-coupled receptor latrophilin 3 (ADGRL3), a cell adhesion molecule highly expressed in the central nervous system, acts in synapse formation through trans interactions with its ligands. It is largely unknown if these interactions serve a purely adhesive function or can modulate G protein signaling. To assess how different structural elements of ADGRL3 (e.g., the adhesive domains, autoproteolytic cleavage site, or tethered agonist (TA)) impact receptor function, we require constructs that disrupt specific receptor features without impacting others. While we showed previously that mutating conserved Phe and Met residues in the TA of ADGRL3-C-terminal fragment (CTF), a CTF truncated to the G protein-coupled receptor proteolysis site, abolishes receptor-mediated G protein activation, we now find that autoproteolytic cleavage is disrupted in the full-length version of this construct. To identify a construct that disrupts TA-dependent activity without impacting proteolysis, we explored other mutations in the TA. We found that mutating the sixth and seventh residues of the TA, Leu and Met, to Ala impaired activity in a serum response element activity assay for both full-length and CTF constructs. We confirmed this activity loss results from impaired G protein coupling using an assay that acutely exposes the TA through controlled proteolysis. The ADGRL3 mutant expresses normally at the cell surface, and immunoblotting shows that it undergoes normal autoproteolysis. Thus, we found a construct that disrupts tethered agonism while retaining autoproteolytic cleavage, providing a tool to disentangle these functions in vivo. Our approach and specific findings are likely to be broadly applicable to other adhesion receptors.
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Affiliation(s)
- Nicole A Perry-Hauser
- Departments of Psychiatry and Molecular Pharmacology and Therapeutics, Columbia University Vagelos College of Physicians and Surgeons, New York, New York, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York, USA
| | - Max W VanDyck
- Department of Biochemistry, Vassar College, Poughkeepsie, New York, USA
| | - Kuo Hao Lee
- Computational Chemistry and Molecular Biophysics Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, Baltimore, Maryland, USA
| | - Lei Shi
- Computational Chemistry and Molecular Biophysics Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, Baltimore, Maryland, USA
| | - Jonathan A Javitch
- Departments of Psychiatry and Molecular Pharmacology and Therapeutics, Columbia University Vagelos College of Physicians and Surgeons, New York, New York, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York, USA.
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43
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Parnell E, Voorn RA, Martin-de-Saavedra MD, Loizzo DD, Dos Santos M, Penzes P. A developmental delay linked missense mutation in Kalirin-7 disrupts protein function and neuronal morphology. Front Mol Neurosci 2022; 15:994513. [PMID: 36533124 PMCID: PMC9751355 DOI: 10.3389/fnmol.2022.994513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/28/2022] [Indexed: 07/30/2023] Open
Abstract
The Rac1 guanine exchange factor Kalirin-7 is a key regulator of dendritic spine morphology, LTP and dendritic arborization. Kalirin-7 dysfunction and genetic variation has been extensively linked to various neurodevelopmental and neurodegenerative disorders. Here we characterize a Kalirin-7 missense mutation, glu1577lys (E1577K), identified in a patient with severe developmental delay. The E1577K point mutation is located within the catalytic domain of Kalirin-7, and results in a robust reduction in Kalirin-7 Rac1 Guanosine exchange factor activity. In contrast to wild type Kalirin-7, the E1577K mutant failed to drive dendritic arborization, spine density, NMDAr targeting to, and activity within, spines. Together these results indicate that reduced Rac1-GEF activity as result of E1577K mutation impairs neuroarchitecture, connectivity and NMDAr activity, and is a likely contributor to impaired neurodevelopment in a patient with developmental delay.
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Affiliation(s)
- Euan Parnell
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Roos A. Voorn
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - M. Dolores Martin-de-Saavedra
- Department of Biochemistry and Molecular Biology, School of Pharmacy, Instituto Universitario de Investigación en Neuroquímica, Complutense University of Madrid, Madrid, Spain
| | - Daniel D. Loizzo
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Marc Dos Santos
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Peter Penzes
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
- Centre for Autism and Neurodevelopment, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
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44
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Fu T, Zhang H, Zheng Q. Molecular Insights into the Heterotropic Allosteric Mechanism in Cytochrome P450 3A4-Mediated Midazolam Metabolism. J Chem Inf Model 2022; 62:5762-5770. [PMID: 36342224 DOI: 10.1021/acs.jcim.2c01264] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cytochrome P450 3A4 (CYP3A4) is the main P450 enzyme for drug metabolism and drug-drug interactions (DDIs), as it is involved in the metabolic process of approximately 50% of drugs. A detailed mechanistic elucidation of DDIs mediated by CYP3A4 is commonly believed to be critical for drug optimization and rational use. Here, two typical probes, midazolam (MDZ, substrate) and testosterone (TST, allosteric effector), are used to investigate the molecular mechanism of CYP3A4-mediated heterotropic allosteric interactions, through conventional molecular dynamics (cMD) and well-tempered metadynamics (WT-MTD) simulations. Distance monitoring shows that TST can stably bind in two potential peripheral sites (Site 1 and Site 2) of CYP3A4. The binding of TST at these two sites can induce conformational changes in CYP3A4 flexible loops on the basis of conformational analysis, thereby promoting the transition of the MDZ binding mode and affecting the ratio of MDZ metabolites. According to the results of the residue interaction network, multiple allosteric communication pathways are identified that can provide vivid and applicable insights into the heterotropic allostery of TST on MDZ metabolism. Comparing the regulatory effects and the communication pathways, the allosteric effect caused by TST binding in Site 2 seems to be more pronounced than in Site 1. Our findings could provide a deeper understanding of CYP3A4-mediated heterotropic allostery at the atomic level and would be helpful for rational drug use as well as the design of new allosteric modulators.
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Affiliation(s)
- Tingting Fu
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China
| | - Hongxing Zhang
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China
| | - Qingchuan Zheng
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China.,Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, Jilin University, Changchun 130023, China
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Moreira NCDS, Tamarozzi ER, Lima JEBDF, Piassi LDO, Carvalho I, Passos GA, Sakamoto-Hojo ET. Novel Dual AChE and ROCK2 Inhibitor Induces Neurogenesis via PTEN/AKT Pathway in Alzheimer's Disease Model. Int J Mol Sci 2022; 23:ijms232314788. [PMID: 36499116 PMCID: PMC9737254 DOI: 10.3390/ijms232314788] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/07/2022] [Accepted: 11/15/2022] [Indexed: 11/29/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive and complex neurodegenerative disease. Acetylcholinesterase inhibitors (AChEIs) are a major class of drugs used in AD therapy. ROCK2, another promising target for AD, has been associated with the induction of neurogenesis via PTEN/AKT. This study aimed to characterize the therapeutic potential of a novel donepezil-tacrine hybrid compound (TA8Amino) to inhibit AChE and ROCK2 protein, leading to the induction of neurogenesis in SH-SY5Y cells. Experiments were carried out with undifferentiated and neuron-differentiated SH-SY5Y cells submitted to treatments with AChEIs (TA8Amino, donepezil, and tacrine) for 24 h or 7 days. TA8Amino was capable of inhibiting AChE at non-cytotoxic concentrations after 24 h. Following neuronal differentiation for 7 days, TA8Amino and donepezil increased the percentage of neurodifferentiated cells and the length of neurites, as confirmed by β-III-tubulin and MAP2 protein expression. TA8Amino was found to participate in the activation of PTEN/AKT signaling. In silico analysis showed that TA8Amino can stably bind to the active site of ROCK2, and in vitro experiments in SH-SY5Y cells demonstrate that TA8Amino significantly reduced the expression of ROCK2 protein, contrasting with donepezil and tacrine. Therefore, these results provide important information on the mechanism underlying the action of TA8Amino with regard to multi-target activities.
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Affiliation(s)
| | - Elvira Regina Tamarozzi
- Department of Biotechnology, School of Arts, Sciences and Humanities—USP, São Paulo 03828-000, Brazil
| | | | - Larissa de Oliveira Piassi
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo—USP, Ribeirão Preto 14049-900, Brazil
| | - Ivone Carvalho
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo—USP, Ribeirão Preto 14040-900, Brazil
| | - Geraldo Aleixo Passos
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo—USP, Ribeirão Preto 14049-900, Brazil
- Laboratory of Genetics and Molecular Biology, Department of Basic and Oral Biology, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, Brazil
| | - Elza Tiemi Sakamoto-Hojo
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo—USP, Ribeirão Preto 14049-900, Brazil
- Department of Biology, Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo—USP, Ribeirão Preto 14040-901, Brazil
- Correspondence: ; Tel.: +55-16-3315-3827
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Yang ZK, Huang XL, Peng L. Transcriptome analysis reveals gene expression changes of the basidiomycetous yeast Apiotrichum mycotoxinivorans in response to ochratoxin A exposure. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 246:114146. [PMID: 36215880 DOI: 10.1016/j.ecoenv.2022.114146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 09/23/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Ochratoxin A (OTA) is one of the most common and deleterious mycotoxins found in food and feedstuffs worldwide; however, Apiotrichum mycotoxinivorans can detoxify OTA. Our results show that A. mycotoxinivorans GUM1709 efficiently degraded OTA, but it caused the accumulation of intracellular reactive oxygen species. The main aim of this study was to identify potential OTA-detoxifying enzymes and to explore the effects of OTA on A. mycotoxinivorans GMU1709. RNA-seq data revealed that 1643 and 1980 genes were significantly upregulated and downregulated, respectively, after OTA exposure. Functional enrichment analyses indicated that OTA exposure enhanced defense capability, protein transport, endocytosis, and energy metabolism; caused ribosomal stress; suppressed DNA replication and transcription; inhibited cell growth and division; and promoted cell death. The integration of secretome, gene expression, and molecular docking analyses revealed that two carboxypeptidase homologues (members of the metallocarboxypeptidase family) were most likely responsible for the detoxification of both extracellular and intracellular OTA. Superoxide dismutase and catalase were the main genes activated in response to oxidative stress. In addition, analysis of key genes associated with cell division and apoptosis showed that OTA exposure inhibited mitosis and promoted cell death. This study revealed the possible OTA response and detoxification mechanisms in A. mycotoxinivorans.
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Affiliation(s)
- Zhi-Kai Yang
- Innovation centre for Advanced Interdisciplinary Medicine, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
| | - Xue-Ling Huang
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science and Technology, Jinan University, Guangzhou, China
| | - Liang Peng
- Department of Clinical Laboratory, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
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Indari O, Kumar Singh A, Tiwari D, Chandra Jha H, Nath Jha A. Deciphering antiviral efficacy of malaria box compounds against malaria exacerbating viral pathogens- Epstein Barr Virus and SARS-CoV-2, an in silico study. MEDICINE IN DRUG DISCOVERY 2022; 16:100146. [DOI: 10.1016/j.medidd.2022.100146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 08/18/2022] [Accepted: 09/04/2022] [Indexed: 11/10/2022] Open
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Oselusi S, Fadaka AO, Wyckoff GJ, Egieyeh SA. Computational Target-Based Screening of Anti-MRSA Natural Products Reveals Potential Multitarget Mechanisms of Action through Peptidoglycan Synthesis Proteins. ACS OMEGA 2022; 7:37896-37906. [PMID: 36312373 PMCID: PMC9609086 DOI: 10.1021/acsomega.2c05061] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 10/06/2022] [Indexed: 05/22/2023]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of bacterial infections in both healthcare and community settings. MRSA can acquire resistance to any current antibiotic, which has major implications for its current and future treatment options. As such, it is globally a major focus for infection control efforts. The mechanical rigidity provided by peptidoglycans in the bacteria cell walls makes it a promising target for broad-spectrum antibacterial drug discovery. The development of drugs that can target different stages of the synthesis of peptidoglycan in MRSA may compromise the integrity of its cell wall and consequently result in the rapid decline of diseases associated with this drug-resistant bacteria. The present study is aimed at screening natural products with known in vitro activities against MRSA to identify their potential to inhibit the proteins involved in the biosynthesis of the peptidoglycan cell wall. A total of 262 compounds were obtained when a literature survey was conducted on anti-MRSA natural products (AMNPs). Virtual screening of the AMNPs was performed against various proteins (targets) that are involved in the biosynthesis of the peptidoglycan (PPC) cell wall using Schrödinger software (release 2020-3) to determine their binding affinities. Nine AMNPs were identified as potential multitarget inhibitors against peptidoglycan biosynthesis proteins. Among these compounds, DB211 showed the strongest binding affinity and interactions with six protein targets, representing three stages of peptidoglycan biosynthesis, and thus was selected as the most promising compound. The MD simulation results for DB211 and its proteins indicated that the protein-ligand complexes were relatively stable over the simulation period of 100 ns. In conclusion, DB211 showed the potential to inhibit six proteins involved in the biosynthesis of the peptidoglycan cell wall in MRSA, thus reducing the chance of MRSA developing resistance to this compound. Therefore, DB211 provided a starting point for the design of new compounds that can inhibit multiple targets in the biosynthesis of the peptidoglycan layer in MRSA.
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Affiliation(s)
- Samson
Olaitan Oselusi
- University
of the Western Cape, School of Pharmacy,
Faculty of Natural Sciences, Robert Sobukwe Road, Bellville, Cape Town, Western Cape ZA 7535, South Africa
| | - Adewale Oluwaseun Fadaka
- University
of the Western Cape, Science and Innovation/Mintek
Nanotechnology Innovation Centre, Department of Biotechnology, Faculty
of Natural Sciences, Robert
Sobukwe Road, Bellville, Cape Town, Western Cape ZA 7535, South Africa
| | - Gerald J. Wyckoff
- University
of Missouri Kansas City, School of Pharmacy,
Division of Pharmacology and Pharmaceutical Sciences, 5000 Holmes Street, Kansas
City, Missouri 64110-2446, United States
| | - Samuel Ayodele Egieyeh
- University
of the Western Cape, School of Pharmacy,
Faculty of Natural Sciences, Robert Sobukwe Road, Bellville, Cape Town, Western Cape ZA 7535, South Africa
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Medina A, Jiménez E, Caballero I, Castellví A, Triviño Valls J, Alcorlo M, Molina R, Hermoso JA, Sammito MD, Borges R, Usón I. Verification: model-free phasing with enhanced predicted models in ARCIMBOLDO_SHREDDER. Acta Crystallogr D Struct Biol 2022; 78:1283-1293. [PMID: 36322413 PMCID: PMC9629495 DOI: 10.1107/s2059798322009706] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 10/03/2022] [Indexed: 11/23/2022] Open
Abstract
Structure predictions have matched the accuracy of experimental structures from close homologues, providing suitable models for molecular replacement phasing. Even in predictions that present large differences due to the relative movement of domains or poorly predicted areas, very accurate regions tend to be present. These are suitable for successful fragment-based phasing as implemented in ARCIMBOLDO. The particularities of predicted models are inherently addressed in the new predicted_model mode, rendering preliminary treatment superfluous but also harmless. B-value conversion from predicted LDDT or error estimates, the removal of unstructured polypeptide, hierarchical decomposition of structural units from domains to local folds and systematically probing the model against the experimental data will ensure the optimal use of the model in phasing. Concomitantly, the exhaustive use of models and stereochemistry in phasing, refinement and validation raises the concern of crystallographic model bias and the need to critically establish the information contributed by the experiment. Therefore, in its predicted_model mode ARCIMBOLDO_SHREDDER will first determine whether the input model already constitutes a solution or provides a straightforward solution with Phaser. If not, extracted fragments will be located. If the landscape of solutions reveals numerous, clearly discriminated and consistent probes or if the input model already constitutes a solution, model-free verification will be activated. Expansions with SHELXE will omit the partial solution seeding phases and all traces outside their respective masks will be combined in ALIXE, as far as consistent. This procedure completely eliminates the molecular replacement search model in favour of the inferences derived from this model. In the case of fragments, an incorrect starting hypothesis impedes expansion. The predicted_model mode has been tested in different scenarios.
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Affiliation(s)
- Ana Medina
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Elisabet Jiménez
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Iracema Caballero
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Albert Castellví
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Josep Triviño Valls
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Martin Alcorlo
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry ‘Rocasolano’, Spanish National Research Council (CSIC), Madrid, Spain
| | - Rafael Molina
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry ‘Rocasolano’, Spanish National Research Council (CSIC), Madrid, Spain
| | - Juan A. Hermoso
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry ‘Rocasolano’, Spanish National Research Council (CSIC), Madrid, Spain
| | - Massimo D. Sammito
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Rafael Borges
- Department of Biophysics and Pharmacology, Biosciences Institute, São Paulo State University (UNESP), Botucatu, Sao Paulo 18618-689, Brazil
| | - Isabel Usón
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain,ICREA, Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08003 Barcelona, Spain,Correspondence e-mail:
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50
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Jaradat R, Li X, Chen H, Stathopulos PB, Bai D. The Hydrophobic Residues in Amino Terminal Domains of Cx46 and Cx50 Are Important for Their Gap Junction Channel Ion Permeation and Gating. Int J Mol Sci 2022; 23:ijms231911605. [PMID: 36232905 PMCID: PMC9570504 DOI: 10.3390/ijms231911605] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 11/09/2022] Open
Abstract
Lens gap junctions (GJs) formed by Cx46 and Cx50 are important to keep lens transparency. Functional studies on Cx46 and Cx50 GJs showed that the Vj-gating, single channel conductance (γj), gating polarity, and/or channel open stability could be modified by the charged residues in the amino terminal (NT) domain. The role of hydrophobic residues in the NT on GJ properties is not clear. Crystal and cryo-EM GJ structures have been resolved, but the NT domain structure has either not been resolved or has showed very different orientations depending on the component connexins and possibly other experimental conditions, making it difficult to understand the structural basis of the NT in Vj-gating and γj. Here, we generated missense variants in Cx46 and Cx50 NT domains and studied their properties by recombinant expression and dual whole-cell patch clamp experiments on connexin-deficient N2A cells. The NT variants (Cx46 L10I, N13E, A14V, Q15N, and Cx50 I10L, E13N, V14A, N15Q) were all able to form functional GJs with similar coupling%, except Cx46 N13E, which showed a significantly reduced coupling%. The GJs of Cx46 N13E, A14V and Cx50 E13N, N15Q showed a reduced coupling conductance. Vj-gating of all the variant GJs were similar to the corresponding wild-type GJs except Cx46 L10I. The γj of Cx46 N13E, A14V, Cx50 E13N, and N15Q GJs was reduced to 51%, 82%, 87%, and 74%, respectively, as compared to their wild-type γjs. Structural models of Cx46 L10I and A14V predicted steric clashes between these residues and the TM2 residues, which might be partially responsible for our observed changes in GJ properties. To verify the importance of hydrophobic interactions, we generated a variant, Cx50 S89T, which also shows a steric clash and failed to form a functional GJ. Our experimental results and structure models indicate that hydrophobic interactions between the NT and TM2 domain are important for their Vj-gating, γj, and channel open stability in these and possibly other GJs.
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