1
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Thapliyal C, Mishra R. The Chaperone-Active State of HdeB at pH 4 Arises from Its Conformational Rearrangement and Enhanced Stability Instead of Surface Hydrophobicity. Biochemistry 2024; 63:1147-1161. [PMID: 38640496 DOI: 10.1021/acs.biochem.4c00132] [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: 04/21/2024]
Abstract
HdeA and HdeB are dimeric ATP-independent acid-stress chaperones, which protect the periplasmic proteins of enteric bacteria at pH 2.0 and 4.0, respectively, during their passage through the acidic environment of the mammalian stomach. Despite being structurally similar, they exhibit distinct functional pH optima and conformational prerequisite for their chaperone action. HdeA undergoes a dimer-to-monomer transition at pH 2.0, whereas HdeB remains dimeric at pH 4.0. The monomerization of HdeA exposes its hydrophobic motifs, which facilitates its interaction with the partially folded substrates. How HdeB functions despite maintaining its dimeric conformation has been poorly elucidated in the literature. Herein, we characterized the conformational states and stability of HdeB at its physiologically relevant pH and compared the data with those of HdeA. At pH 4.0, HdeB exhibited distinct spectroscopic signatures and higher stability against heat and guanidine-HCl-induced denaturation than at pH 7.5. We affirm that the pH 4.0 conformer of HdeB was distinct from that at pH 7.5 and that these two conformational states were hierarchically unrelated. Salt-bridge mutations that perturbed HdeB's intersubunit interactions resulted in the loss of its stability and function at pH 4.0. In contrast, mutations affecting intrasubunit interactions enhanced its function, albeit with a reduction in stability. These findings suggest that, unlike HdeA, HdeB acts as a noncanonical chaperone, where pH-dependent stability and conformational rearrangement at pH 4.0 play a core role in its chaperone function rather than its surface hydrophobicity. Such rearrangement establishes a stability-function trade-off that allows HdeB to function while maintaining its stable dimeric state.
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Affiliation(s)
- Charu Thapliyal
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rajesh Mishra
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
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2
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Hall LM, Munasinghe VS, Vella NGF, Ellis JT, Stark D. Observations on the transmission of Dientamoeba fragilis and the cyst life cycle stage. Parasitology 2024; 151:337-345. [PMID: 38250789 PMCID: PMC11007279 DOI: 10.1017/s0031182024000076] [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: 07/20/2023] [Revised: 11/20/2023] [Accepted: 01/11/2024] [Indexed: 01/23/2024]
Abstract
Little is known about the life cycle and mode of transmission of Dientamoeba fragilis. Recently it was suggested that fecal–oral transmission of cysts may play a role in the transmission of D. fragilis. In order to establish an infection, D. fragilis is required to remain viable when exposed to the pH of the stomach. In this study, we investigated the ability of cultured trophozoites to withstand the extremes of pH. We provide evidence that trophozoites of D. fragilis are vulnerable to highly acidic conditions. We also investigated further the ultrastructure of D. fragilis cysts obtained from mice and rats by transmission electron microscopy. These studies of cysts showed a clear cyst wall surrounding an encysted parasite. The cyst wall was double layered with an outer fibrillar layer and an inner layer enclosing the parasite. Hydrogenosomes, endoplasmic reticulum and nuclei were present in the cysts. Pelta-axostyle structures, costa and axonemes were identifiable and internal flagellar axonemes were present. This study therefore provides additional novel details and knowledge of the ultrastructure of the cyst stage of D. fragilis.
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Affiliation(s)
- Luke M. Hall
- School of Life Sciences, University of Technology Sydney, Broadway, NSW 2007, Australia
- Division of Microbiology, Sydpath, St Vincent's Hospital, Darlinghurst, NSW 2010, Australia
| | - Varuni S. Munasinghe
- School of Life Sciences, University of Technology Sydney, Broadway, NSW 2007, Australia
| | - Nicole G. F. Vella
- Macquarie University Microscopy Unit, Faculty of Science and Engineering, Macquarie University, North Ryde, NSW 2109, Australia
| | - John T. Ellis
- School of Life Sciences, University of Technology Sydney, Broadway, NSW 2007, Australia
| | - Damien Stark
- Division of Microbiology, Sydpath, St Vincent's Hospital, Darlinghurst, NSW 2010, Australia
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3
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Serebryany E, Zhao VY, Park K, Bitran A, Trauger SA, Budnik B, Shakhnovich EI. Systematic conformation-to-phenotype mapping via limited deep sequencing of proteins. Mol Cell 2023; 83:1936-1952.e7. [PMID: 37267908 PMCID: PMC10281453 DOI: 10.1016/j.molcel.2023.05.006] [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: 04/12/2022] [Revised: 01/29/2023] [Accepted: 05/03/2023] [Indexed: 06/04/2023]
Abstract
Non-native conformations drive protein-misfolding diseases, complicate bioengineering efforts, and fuel molecular evolution. No current experimental technique is well suited for elucidating them and their phenotypic effects. Especially intractable are the transient conformations populated by intrinsically disordered proteins. We describe an approach to systematically discover, stabilize, and purify native and non-native conformations, generated in vitro or in vivo, and directly link conformations to molecular, organismal, or evolutionary phenotypes. This approach involves high-throughput disulfide scanning (HTDS) of the entire protein. To reveal which disulfides trap which chromatographically resolvable conformers, we devised a deep-sequencing method for double-Cys variant libraries of proteins that precisely and simultaneously locates both Cys residues within each polypeptide. HTDS of the abundant E. coli periplasmic chaperone HdeA revealed distinct classes of disordered hydrophobic conformers with variable cytotoxicity depending on where the backbone was cross-linked. HTDS can bridge conformational and phenotypic landscapes for many proteins that function in disulfide-permissive environments.
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Affiliation(s)
- Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Victor Y Zhao
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Kibum Park
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Amir Bitran
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Sunia A Trauger
- Center for Mass Spectrometry, Harvard University, Cambridge, MA 02138, USA
| | - Bogdan Budnik
- Center for Mass Spectrometry, Harvard University, Cambridge, MA 02138, USA
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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4
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Nakata Y, Kitazaki Y, Kanaoka H, Shingen E, Uehara R, Hongo K, Kawata Y, Mizobata T. Formation of Fibrils by the Periplasmic Molecular Chaperone HdeB from Escherichia coli. Int J Mol Sci 2022; 23:ijms232113243. [PMID: 36362039 PMCID: PMC9657021 DOI: 10.3390/ijms232113243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/19/2022] [Accepted: 10/27/2022] [Indexed: 11/06/2022] Open
Abstract
The molecular chaperones HdeA and HdeB of the Escherichia coli (E. coli) periplasm protect client proteins from acid denaturation through a unique mechanism that utilizes their acid denatured states to bind clients. We previously demonstrated that the active, acid-denatured form of HdeA is also prone to forming inactive, amyloid fibril-like aggregates in a pH-dependent, reversible manner. In this study, we report that HdeB also displays a similar tendency to form fibrils at low pH. HdeB fibrils were observed at pH < 3 in the presence of NaCl. Similar to HdeA, HdeB fibrils could be resolubilized by a simple shift to neutral pH. In the case of HdeB, however, we found that after extended incubation at low pH, HdeB fibrils were converted into a form that could not resolubilize at pH 7. Fresh fibrils seeded from these “transformed” fibrils were also incapable of resolubilizing at pH 7, suggesting that the transition from reversible to irreversible fibrils involved a specific conformational change that was transmissible through fibril seeds. Analyses of fibril secondary structure indicated that HdeB fibrils retained significant alpha helical content regardless of the conditions under which fibrils were formed. Fibrils that were formed from HdeB that had been treated to remove its intrinsic disulfide bond also were incapable of resolubilizing at pH 7, suggesting that certain residual structures that are retained in acid-denatured HdeB are important for this protein to recover its soluble state from the fibril form.
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Affiliation(s)
- Yui Nakata
- Department of Chemistry and Biotechnology, Tottori University, Tottori 680-8552, Japan
| | - Yuuto Kitazaki
- Department of Chemistry and Biotechnology, Tottori University, Tottori 680-8552, Japan
| | - Hitomi Kanaoka
- Department of Chemistry and Biotechnology, Tottori University, Tottori 680-8552, Japan
| | - Erika Shingen
- Department of Chemistry and Biotechnology, Tottori University, Tottori 680-8552, Japan
| | - Rina Uehara
- Course of Biotechnology, Graduate School of Sustainable Social Sciences, Tottori University, Tottori 680-8552, Japan
| | - Kunihiro Hongo
- Department of Chemistry and Biotechnology, Tottori University, Tottori 680-8552, Japan
- Course of Biotechnology, Graduate School of Sustainable Social Sciences, Tottori University, Tottori 680-8552, Japan
- Center for Green Sustainable Chemistry, Faculty of Engineering, Tottori University, Tottori 680-8552, Japan
| | - Yasushi Kawata
- Department of Chemistry and Biotechnology, Tottori University, Tottori 680-8552, Japan
- Course of Biotechnology, Graduate School of Sustainable Social Sciences, Tottori University, Tottori 680-8552, Japan
- Center for Green Sustainable Chemistry, Faculty of Engineering, Tottori University, Tottori 680-8552, Japan
| | - Tomohiro Mizobata
- Department of Chemistry and Biotechnology, Tottori University, Tottori 680-8552, Japan
- Course of Biotechnology, Graduate School of Sustainable Social Sciences, Tottori University, Tottori 680-8552, Japan
- Center for Green Sustainable Chemistry, Faculty of Engineering, Tottori University, Tottori 680-8552, Japan
- Correspondence: ; Tel.: +81-857-31-5691
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5
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Bondos SE, Dunker AK, Uversky VN. Intrinsically disordered proteins play diverse roles in cell signaling. Cell Commun Signal 2022; 20:20. [PMID: 35177069 PMCID: PMC8851865 DOI: 10.1186/s12964-022-00821-7] [Citation(s) in RCA: 67] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/11/2021] [Indexed: 11/29/2022] Open
Abstract
Signaling pathways allow cells to detect and respond to a wide variety of chemical (e.g. Ca2+ or chemokine proteins) and physical stimuli (e.g., sheer stress, light). Together, these pathways form an extensive communication network that regulates basic cell activities and coordinates the function of multiple cells or tissues. The process of cell signaling imposes many demands on the proteins that comprise these pathways, including the abilities to form active and inactive states, and to engage in multiple protein interactions. Furthermore, successful signaling often requires amplifying the signal, regulating or tuning the response to the signal, combining information sourced from multiple pathways, all while ensuring fidelity of the process. This sensitivity, adaptability, and tunability are possible, in part, due to the inclusion of intrinsically disordered regions in many proteins involved in cell signaling. The goal of this collection is to highlight the many roles of intrinsic disorder in cell signaling. Following an overview of resources that can be used to study intrinsically disordered proteins, this review highlights the critical role of intrinsically disordered proteins for signaling in widely diverse organisms (animals, plants, bacteria, fungi), in every category of cell signaling pathway (autocrine, juxtacrine, intracrine, paracrine, and endocrine) and at each stage (ligand, receptor, transducer, effector, terminator) in the cell signaling process. Thus, a cell signaling pathway cannot be fully described without understanding how intrinsically disordered protein regions contribute to its function. The ubiquitous presence of intrinsic disorder in different stages of diverse cell signaling pathways suggest that more mechanisms by which disorder modulates intra- and inter-cell signals remain to be discovered.
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Affiliation(s)
- Sarah E. Bondos
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843 USA
| | - A. Keith Dunker
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202 USA
| | - Vladimir N. Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer’s Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612 USA
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Pushchino, Moscow Region, Russia 142290
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6
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Tartilán-Choya B, Sidhu-Muñoz RS, Vizcaíno N. The Transcriptional Regulator MucR, but Not Its Controlled Acid-Activated Chaperone HdeA, Is Essential for Virulence and Modulates Surface Architecture and Properties in Brucella ovis PA. Front Vet Sci 2022; 8:814752. [PMID: 35174240 PMCID: PMC8843074 DOI: 10.3389/fvets.2021.814752] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 12/16/2021] [Indexed: 11/13/2022] Open
Abstract
Brucella ovis is a non-zoonotic bacterium causing contagious epididymitis and other genital lesions in rams and responsible for significant economic losses in sheep-breeding areas. It is a naturally rough (without O-chains in the lipopolysaccharide) Brucella species whose virulence mechanisms have been less explored than those of zoonotic smooth brucellae (bearing O-chains that mask other outer membrane molecules). Considering the rough nature of Brucella ovis, the influence of surface components other than O-chains on its biological properties may be greater than in smooth Brucella species. Here we describe the construction and characterization of the mucR deletion mutant of virulent B. ovis PA, which is defective in a transcriptional regulator, affecting surface properties and virulence in smooth brucellae. This mutant showed increased amounts of three proteins identified as HdeA (acid-activated chaperone), Omp25d (outer membrane protein undetectable in the parental strain), and BOV_A0299 (hypothetical protein of unknown function). This observation correlated with the enhanced transcription of the corresponding genes and constitutes the first report on this type of proteome alteration in Brucella ΔmucR mutants. The upstream regions of the three genes contained AT rich domains with T-A steps described as binding sites for MucR in the Brucella abortus 2308 babR promoter (gene also upregulated in B. ovis ΔmucR), which suggests that hdeA, omp25d, and BOV_A0299 expression could be repressed by MucR through a direct binding to their promoter regions. Relative quantification of transcripts of several other genes selected according to the transcriptome of smooth brucellae ΔmucR mutants revealed not only similarities but also relevant differences among strains, such as those detected in flagellar and virB genes. Periplasmic HdeA has been related to the resistance of B. abortus to acidic pH, conditions encountered by Brucella inside phagocytes, but the deletion of hdeA in B. ovis PA and the ΔmucR mutant did not modify any of the evaluated properties of these strains. The B. ovis PA ΔmucR and ΔmucRΔhdeA mutants had defective in vitro growth and altered surface properties and architecture, exemplified by detectable amounts of Omp25d. Moreover, they showed virulence attenuation but established persistent splenic infection in mice, which encourages their evaluation as specifical attenuated vaccines against B. ovis.
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Affiliation(s)
| | - Rebeca S. Sidhu-Muñoz
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain
| | - Nieves Vizcaíno
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain
- *Correspondence: Nieves Vizcaíno
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7
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Ren C, Zheng Y, Liu C, Mencius J, Wu Z, Quan S. Molecular Characterization of an Intrinsically Disordered Chaperone Reveals Net-Charge Regulation in Chaperone Action. J Mol Biol 2021; 434:167405. [PMID: 34914967 DOI: 10.1016/j.jmb.2021.167405] [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: 08/13/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 11/18/2022]
Abstract
Molecular chaperones are diverse biomacromolecules involved in the maintenance of cellular protein homeostasis (proteostasis). Here we demonstrate that in contrast to most chaperones with defined three-dimensional structures, the acid-inducible protein Asr in Escherichia coli is intrinsically disordered and exhibits varied aggregation-preventing or aggregation-promoting activities, acting as a "conditionally active chaperone". Bioinformatics and experimental analyses of Asr showed that it is devoid of hydrophobic patches but rich in positive charges and local polyproline II backbone structures. Asr contributes to the integrity of the bacterial outer membrane under mildly acidic conditions in vivo and possesses chaperone activities toward model clients in vitro. Notably, its chaperone activity is dependent on the net charges of clients: on the one hand, it inhibits the aggregation of clients with similar net charges; on the other hand, it stimulates the aggregation of clients with opposite net charges. Mutational analysis confirmed that positively charged residues in Asr are essential for the varied effects on protein aggregation, suggesting that electrostatic interactions are the major driving forces underlying Asr's proteostasis-related activity. These findings present a unique example of an intrinsically disordered molecular chaperone with distinctive dual functions-as an aggregase or as a chaperone-depending on the net charges of clients.
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Affiliation(s)
- Chang Ren
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai Collaborative Innovation Center for Biomanufacturing (SCICB), Shanghai 200237, China
| | - Yongxin Zheng
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai Collaborative Innovation Center for Biomanufacturing (SCICB), Shanghai 200237, China
| | - Chunlan Liu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai Collaborative Innovation Center for Biomanufacturing (SCICB), Shanghai 200237, China
| | - Jun Mencius
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai Collaborative Innovation Center for Biomanufacturing (SCICB), Shanghai 200237, China
| | - Zhili Wu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai Collaborative Innovation Center for Biomanufacturing (SCICB), Shanghai 200237, China
| | - Shu Quan
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai Collaborative Innovation Center for Biomanufacturing (SCICB), Shanghai 200237, China; Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Shanghai 200237, China.
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8
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The challenges and prospects of Escherichia coli as an organic acid production host under acid stress. Appl Microbiol Biotechnol 2021; 105:8091-8107. [PMID: 34617140 DOI: 10.1007/s00253-021-11577-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Organic acids have a wide range of applications and have attracted the attention of many industries, and their large-scale applications have led fermentation production to low-cost development. Among them, the microbial fermentation method, especially using Escherichia coli as the production host, has the advantages of fast growth and low energy consumption, and has gradually shown better advantages and prospects in organic acid fermentation production. IMPORTANCE However, when the opportunity comes, the acidified environment caused by the acid products accumulated during the fermentation process also challenges E. coli. The acid sensitivity of E. coli is a core problem that needs to be solved urgently. The addition of neutralizers in traditional operations led to the emergence of osmotic stress inadvertently, the addition of strong acid substances to recover products in the salt state not only increases production costs, but the discharged sewage is also harmful to the environment. ELABORATION This article summarizes the current status of the application of E. coli in the production of organic acids, and based on the impact of acid stress on the physiological state of cells and the impact of industrial production profits, put forward some new conjectures that can make up for the deficiencies in existing research and application. IMPLICATION At this point, the diversified transformation of E. coli has become a chassis microbe that is more suitable for industrial fermentation, enhancing industrial application value. KEY POINTS • E. coli is a potential host for high value-added organic acids production. • Classify the damage mechanism and coping strategies of E. coli when stimulated by acid molecules. • Multi-dimensional expansion tools are needed to create acid-resistant E. coli chassis.
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Groisman EA, Duprey A, Choi J. How the PhoP/PhoQ System Controls Virulence and Mg 2+ Homeostasis: Lessons in Signal Transduction, Pathogenesis, Physiology, and Evolution. Microbiol Mol Biol Rev 2021; 85:e0017620. [PMID: 34191587 PMCID: PMC8483708 DOI: 10.1128/mmbr.00176-20] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The PhoP/PhoQ two-component system governs virulence, Mg2+ homeostasis, and resistance to a variety of antimicrobial agents, including acidic pH and cationic antimicrobial peptides, in several Gram-negative bacterial species. Best understood in Salmonella enterica serovar Typhimurium, the PhoP/PhoQ system consists o-regulated gene products alter PhoP-P amounts, even under constant inducing conditions. PhoP-P controls the abundance of hundreds of proteins both directly, by having transcriptional effects on the corresponding genes, and indirectly, by modifying the abundance, activity, or stability of other transcription factors, regulatory RNAs, protease regulators, and metabolites. The investigation of PhoP/PhoQ has uncovered novel forms of signal transduction and the physiological consequences of regulon evolution.
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Affiliation(s)
- Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
- Yale Microbial Sciences Institute, West Haven, Connecticut, USA
| | - Alexandre Duprey
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| | - Jeongjoon Choi
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
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10
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Aguirre-Cardenas MI, Geddes-Buehre DH, Crowhurst KA. Removal of disulfide from acid stress chaperone HdeA does not wholly eliminate structure or function at low pH. Biochem Biophys Rep 2021; 27:101064. [PMID: 34307907 PMCID: PMC8258783 DOI: 10.1016/j.bbrep.2021.101064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 06/10/2021] [Accepted: 06/24/2021] [Indexed: 11/29/2022] Open
Abstract
HdeA is an acid-stress chaperone that operates in the periplasm of various strains of pathogenic gram-negative bacteria. Its primary function is to prevent irreversible aggregation of other periplasmic proteins when the bacteria enter the acidic environment of the stomach after contaminated food is ingested; its role is therefore to help the bacteria survive long enough to enter and colonize the intestines. The mechanism of operation of HdeA is unusual in that this helical homodimer is inactive when folded at neutral pH but becomes activated at low pH after the dimer dissociates and partially unfolds. Studies with chemical reducing agents previously suggested that the intramolecular disulfide bond is important for maintaining residual structure in HdeA at low pH and may be responsible for positioning exposed hydrophobic residues together for the purpose of binding unfolded client proteins. In order to explore its role in HdeA structure and chaperone function we performed a conservative cysteine to serine mutation of the disulfide. We found that, although residual structure is greatly diminished at pH 2 without the disulfide, it is not completely lost; conversely, the mutant is almost completely random coil at pH 6. Aggregation assays showed that mutated HdeA, although less successful as a chaperone than wild type, still maintains a surprising level of function. These studies highlight that we still have much to learn about the factors that stabilize residual structure at low pH and the role of disulfide bonds.
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Affiliation(s)
- M. Imex Aguirre-Cardenas
- Department of Chemistry and Biochemistry, California State University Northridge, 18111 Nordhoff St., Northridge, CA, 91330-8262, USA
- Present address: Department of Chemistry, University of California Riverside, 900 University Ave, Riverside, CA, 92521, USA
| | - Dane H. Geddes-Buehre
- Department of Chemistry and Biochemistry, California State University Northridge, 18111 Nordhoff St., Northridge, CA, 91330-8262, USA
| | - Karin A. Crowhurst
- Department of Chemistry and Biochemistry, California State University Northridge, 18111 Nordhoff St., Northridge, CA, 91330-8262, USA
- Corresponding author.
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11
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Detection of key sites of dimer dissociation and unfolding initiation during activation of acid-stress chaperone HdeA at low pH. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1869:140576. [PMID: 33253897 DOI: 10.1016/j.bbapap.2020.140576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 11/23/2022]
Abstract
HdeA is a small acid-stress chaperone protein with a unique activity profile. At physiological pH, it forms a folded, but inactive, dimer. Below pH 3.0, HdeA unfolds and dissociates into disordered monomers, utilizing exposed hydrophobic patches to bind other unfolded proteins and prevent their irreversible aggregation. In this way, HdeA has a key role in helping pathogenic bacteria survive our acidic stomach and colonize our intestines, facilitating the spread of dysentery. Despite numerous publications on the topic, there remain questions about the mechanism by which HdeA unfolding and activation are triggered. Previous studies usually assessed HdeA unfolding over pH increments that are too far apart to gain fine detail of the process of unfolding and dimer dissociation, and often employed techniques that prevented thorough evaluation of specific regions of the protein. We used a variety of heteronuclear NMR experiments to investigate changes to backbone and side chain structure and dynamics of HdeA at four pHs between 3.0 and 2.0. We found that the long loop in the dimer interface is an early site of initiation of dimer dissociation, and that a molecular "clasp" near the disulfide bond is broken open at low pH as part, or as a trigger, of unfolding; this process also results in the separation of C-terminal helices and exposure of key hydrophobic client binding sites. Our results highlight important regions of HdeA that may have previously been overlooked because they lie too close to the disulfide bond or are thought to be too dynamic in the folded state to influence unfolding processes.
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12
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Kornspan D, Zahavi T, Salmon-Divon M. The Acidic Stress Response of the Intracellular Pathogen Brucella melitensis: New Insights from a Comparative, Genome-Wide Transcriptome Analysis. Genes (Basel) 2020; 11:genes11091016. [PMID: 32872264 PMCID: PMC7563570 DOI: 10.3390/genes11091016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/23/2020] [Accepted: 08/25/2020] [Indexed: 11/30/2022] Open
Abstract
The intracellular pathogenic bacteria belonging to the genus Brucella must cope with acidic stress as they penetrate the host via the gastrointestinal route, and again during the initial stages of intracellular infection. A transcription-level regulation has been proposed to explain this but the specific molecular mechanisms are yet to be determined. We recently reported a comparative transcriptomic analysis of the attenuated vaccine Brucella melitensis strain Rev.1 against the virulent strain 16M in cultures grown under either neutral or acidic conditions. Here, we re-analyze the RNA-seq data of 16M from our previous study and compare it to published transcriptomic data of this strain from both an in cellulo and an in vivo model. We identify 588 genes that are exclusively differentially expressed in 16M grown under acidic versus neutral pH conditions, including 286 upregulated genes and 302 downregulated genes that are not differentially expressed in either the in cellulo or the in vivo model. Of these, we highlight 13 key genes that are known to be associated with a bacterial response to acidic stress and, in our study, were highly upregulated under acidic conditions. These genes provide new molecular insights into the mechanisms underlying the acid-resistance of Brucella within its host.
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Affiliation(s)
- David Kornspan
- Department of Bacteriology, Kimron Veterinary Institute, Bet Dagan 50250, Israel
- Correspondence: ; Tel.: +972-3-968-1745
| | - Tamar Zahavi
- Genomic Bioinformatics Laboratory, Department of Molecular Biology, Ariel University, Ariel 40700, Israel; (T.Z.); (M.S.-D.)
| | - Mali Salmon-Divon
- Genomic Bioinformatics Laboratory, Department of Molecular Biology, Ariel University, Ariel 40700, Israel; (T.Z.); (M.S.-D.)
- Adelson School of Medicine, Ariel University, Ariel 40700, Israel
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13
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Pacheco S, Widjaja MA, Gomez JS, Crowhurst KA, Abrol R. The complex role of the N-terminus and acidic residues of HdeA as pH-dependent switches in its chaperone function. Biophys Chem 2020; 264:106406. [PMID: 32593908 PMCID: PMC8276670 DOI: 10.1016/j.bpc.2020.106406] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/03/2020] [Accepted: 05/16/2020] [Indexed: 10/24/2022]
Abstract
HdeA is a small acid-stress chaperone protein found in the periplasm of several pathogenic gram-negative bacteria. In neutral pH environments HdeA is an inactive folded homodimer but when exposed to strong acidic environments it partially unfolds and, once activated, binds to other periplasmic proteins, protecting them from irreversible aggregation. Here we use a combination of hydrogen/deuterium exchange NMR experiments and constant pH molecular dynamics simulations to elucidate the role of HdeA's N-terminus in its activation mechanism. Previous work indicates that the N-terminus is flexible and unprotected at high pH while exhibiting interactions with some HdeA client binding site residues. It, however, becomes partially solvent-protected at pH 2.6 - 2.8 and then loses protection again at pH 2.0. This protection is not due to the appearance of new secondary structure, but rather increased contacts between N-terminal residues and the C-terminus of the other protomer in the dimer, as well as concurrent loosening of its hold on the client binding site residues, priming HdeA for interactions with periplasmic client proteins. This work also uncovers unusual protonation profiles of some titratable residues and suggests their complex role in chaperone function.
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Affiliation(s)
- Sayuri Pacheco
- Department of Chemistry and Biochemistry, California State University, Northridge, 18111 Nordhoff St., Northridge, CA 91330, United States of America
| | - Marlyn A Widjaja
- Department of Chemistry and Biochemistry, California State University, Northridge, 18111 Nordhoff St., Northridge, CA 91330, United States of America
| | - Jafaeth S Gomez
- Department of Chemistry and Biochemistry, California State University, Northridge, 18111 Nordhoff St., Northridge, CA 91330, United States of America
| | - Karin A Crowhurst
- Department of Chemistry and Biochemistry, California State University, Northridge, 18111 Nordhoff St., Northridge, CA 91330, United States of America.
| | - Ravinder Abrol
- Department of Chemistry and Biochemistry, California State University, Northridge, 18111 Nordhoff St., Northridge, CA 91330, United States of America.
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14
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Hu Y, Li C, He L, Jin C, Liu M. Mechanisms of Chaperones as Active Assistant/Protector for Proteins: Insights from NMR Studies. CHINESE J CHEM 2020. [DOI: 10.1002/cjoc.201900441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yunfei Hu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS) Wuhan Hubei 430071 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Conggang Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS) Wuhan Hubei 430071 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Lichun He
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS) Wuhan Hubei 430071 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Changwen Jin
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, College of Life Sciences, Peking University Beijing 100871 China
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS) Wuhan Hubei 430071 China
- University of Chinese Academy of Sciences Beijing 100049 China
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15
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The role of bacterial cell envelope structures in acid stress resistance in E. coli. Appl Microbiol Biotechnol 2020; 104:2911-2921. [PMID: 32067056 DOI: 10.1007/s00253-020-10453-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/29/2020] [Accepted: 02/07/2020] [Indexed: 12/14/2022]
Abstract
Acid resistance (AR) is an indispensable mechanism for the survival of neutralophilic bacteria, such as Escherichia coli (E. coli) strains that survive in the gastrointestinal tract. E. coli acid tolerance has been extensively studied during past decades, with most studies focused on gene regulation and mechanisms. However, the role of cell membrane structure in the context of acid stress resistance has not been discussed in depth. Here, we provide a comprehensive review of the roles and mechanisms of the E. coli cell envelope from different membrane components, such as membrane proteins, fatty acids, chaperones, and proton-consuming systems, and particularly focus on the innovative effects revealed by recent studies. We hope that the information guides us to understand the bacterial survival strategies under acid stress and to further explore the AR regulatory mechanisms to prevent or treat E. coli and other related Gram-negative bacteria infection, or to enhance the AR of engineering E. coli.
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16
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Yan Z, Hussain S, Wang X, Bernstein HD, Bardwell JCA. Chaperone OsmY facilitates the biogenesis of a major family of autotransporters. Mol Microbiol 2019; 112:1373-1387. [PMID: 31369167 DOI: 10.1111/mmi.14358] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2019] [Indexed: 12/26/2022]
Abstract
OsmY is a widely conserved but poorly understood 20 kDa periplasmic protein. Using a folding biosensor, we previously obtained evidence that OsmY has molecular chaperone activity. To discover natural OsmY substrates, we screened for proteins that are destabilized and thus present at lower steady-state levels in an osmY-null strain. The abundance of an outer membrane protein called antigen 43 was substantially decreased and its β-barrel domain was undetectable in the outer membrane of an osmY-null strain. Antigen 43 is a member of the diffuse adherence family of autotransporters. Like strains that are defective in antigen 43 production, osmY-null mutants failed to undergo cellular autoaggregation. In vitro, OsmY assisted in the refolding of the antigen 43 β-barrel domain and protected it from added protease. Finally, an osmY-null strain that expressed two members of the diffuse adherence family of autotransporters that are distantly related to antigen 43, EhaA and TibA, contained reduced levels of the proteins and failed to undergo cellular autoaggregation. Taken together, our results indicate that OsmY is involved in the biogenesis of a major subset of autotransporters, a group of proteins that play key roles in bacterial pathogenesis.
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Affiliation(s)
- Zhen Yan
- Howard Hughes Medical Institute and Department of Molecular, Cellular & Development Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Sunyia Hussain
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Xu Wang
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - James C A Bardwell
- Howard Hughes Medical Institute and Department of Molecular, Cellular & Development Biology, University of Michigan, Ann Arbor, MI, 48109, USA
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17
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Xu J, Li T, Gao Y, Deng J, Gu J. MgrB affects the acid stress response of Escherichia coli by modulating the expression of iraM. FEMS Microbiol Lett 2019; 366:fnz123. [PMID: 31158277 DOI: 10.1093/femsle/fnz123] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 06/01/2019] [Indexed: 10/18/2023] Open
Abstract
Although MgrB is established to be a feedback inhibitor of the PhoP/Q system in Escherichia coli, the biological functions of MgrB remain largely unknown. To explore new functions of MgrB, a comparative transcriptome analysis was performed (E. coli K-12 W3110 ΔmgrB vs E. coli K-12 W3110). The results showed that many genes involved in acid stress are upregulated, suggesting that MgrB is related to acid sensitivity in E. coli. The survival rates under acid stress of the ΔmgrB mutant and wild-type showed that deletion of mgrB resulted in acid resistance. According to previous research, we deleted phoP, phoQ and iraM in the ΔmgrB mutant, and found that further deletion of phoP/phoQ only partially restored acid sensitivity. Additionally, we found that deletion of mgrB resulted in increased accumulation of RpoS during the exponential growth phase, which could be blocked by further deletion of iraM. Mutation of iraM or rpoS completely suppressed the effect of mgrB mutation on acid resistance. Taken together, the data suggest that MgrB affects the acid resistance of E. coli by modulating the expression of iraM, but not completely through PhoP/Q. This indicates that MgrB may have other protein interactors aside from PhoQ, which merits further investigation.
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Affiliation(s)
- Jintian Xu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Ting Li
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Yunrong Gao
- The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou 510623, China
| | - Jiaoyu Deng
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- Guangdong Province Key Laboratory of TB Systems Biology and Translational Medicine, Foshan Institude of Industrial Technology, Chinese Academic of Sciences, Foshan 528000, China
| | - Jing Gu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
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18
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Fu X, Chang Z. Biogenesis, quality control, and structural dynamics of proteins as explored in living cells via site-directed photocrosslinking. Protein Sci 2019; 28:1194-1209. [PMID: 31002747 DOI: 10.1002/pro.3627] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/16/2019] [Indexed: 02/06/2023]
Abstract
Protein biogenesis and quality control are essential to maintaining a functional pool of proteins and involve numerous protein factors that dynamically and transiently interact with each other and with the substrate proteins in living cells. Conventional methods are hardly effective for studying dynamic, transient, and weak protein-protein interactions that occur in cells. Herein, we review how the site-directed photocrosslinking approach, which relies on the genetic incorporation of a photoreactive unnatural amino acid into a protein of interest at selected individual amino acid residue positions and the covalent trapping of the interacting proteins upon ultraviolent irradiation, has become a highly efficient way to explore the aspects of protein contacts in living cells. For example, in the past decade, this approach has allowed the profiling of the in vivo substrate proteins of chaperones or proteases under both physiologically optimal and stressful (e.g., acidic) conditions, mapping residues located at protein interfaces, identifying new protein factors involved in the biogenesis of membrane proteins, trapping transiently formed protein complexes, and snapshotting different structural states of a protein. We anticipate that the site-directed photocrosslinking approach will play a fundamental role in dissecting the detailed mechanisms of protein biogenesis, quality control, and dynamics in the future.
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Affiliation(s)
- Xinmiao Fu
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, 350117, China
| | - Zengyi Chang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Center for Protein Science, Beijing, 100871, China
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19
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Subunit interactions as mediated by “non-interface” residues in living cells for multiple homo-oligomeric proteins. Biochem Biophys Res Commun 2019; 512:100-105. [DOI: 10.1016/j.bbrc.2019.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 03/01/2019] [Indexed: 11/22/2022]
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20
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Abstract
The biogenesis of periplasmic and outer membrane proteins (OMPs) in Escherichia coli is assisted by a variety of processes that help with their folding and transport to their final destination in the cellular envelope. Chaperones are macromolecules, usually proteins, that facilitate the folding of proteins or prevent their aggregation without becoming part of the protein's final structure. Because chaperones often bind to folding intermediates, they often (but not always) act to slow protein folding. Protein folding catalysts, on the other hand, act to accelerate specific steps in the protein folding pathway, including disulfide bond formation and peptidyl prolyl isomerization. This review is primarily concerned with E. coli and Salmonella periplasmic and cellular envelope chaperones; it also discusses periplasmic proline isomerization.
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21
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Abstract
The periplasm of Gram-negative bacteria contains a specialized chaperone network that facilitates the transport of unfolded membrane proteins to the outer membrane as its primary functional role. The network, involving the chaperones Skp and SurA as key players and potentially additional chaperones, is indispensable for the survival of the cell. Structural descriptions of the apo forms of these molecular chaperones were initially provided by X-ray crystallography. Subsequently, a combination of experimental biophysical methods including solution NMR spectroscopy provided a detailed understanding of full-length chaperone-client complexes . The data showed that conformational changes and dynamic re-organization of the chaperones upon client binding, as well as client dynamics on the chaperone surface are crucial for function. This chapter gives an overview of the structure-function relationship of the dynamic conformational rearrangements that regulate the functional cycles of the periplasmic molecular chaperones Skp and SurA.
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Affiliation(s)
- Guillaume Mas
- Biozentrum, University of Basel, Klingelbergstrasse 70, Basel, 4056, Switzerland
| | - Johannes Thoma
- Department of Chemistry and Molecular Biology, Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Medicinaregatan 9c, 405 30, Gothenburg, Sweden
| | - Sebastian Hiller
- Biozentrum, University of Basel, Klingelbergstrasse 70, Basel, 4056, Switzerland.
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22
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Gorman SD, D'Amico RN, Winston DS, Boehr DD. Engineering Allostery into Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1163:359-384. [PMID: 31707711 PMCID: PMC7508002 DOI: 10.1007/978-981-13-8719-7_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Our ability to engineer protein structure and function has grown dramatically over recent years. Perhaps the next level in protein design is to develop proteins whose function can be regulated in response to various stimuli, including ligand binding, pH changes, and light. Endeavors toward these goals have tested and expanded on our understanding of protein function and allosteric regulation. In this chapter, we provide examples from different methods for developing new allosterically regulated proteins. These methods range from whole insertion of regulatory domains into new host proteins, to covalent attachment of photoswitches to generate light-responsive proteins, and to targeted changes to specific amino acid residues, especially to residues identified to be important for relaying allosteric information across the protein framework. Many of the examples we discuss have already found practical use in medical and biotechnology applications.
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Affiliation(s)
- Scott D Gorman
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - Rebecca N D'Amico
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - Dennis S Winston
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - David D Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA.
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23
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Yu XC, Hu Y, Ding J, Li H, Jin C. Structural basis and mechanism of the unfolding-induced activation of HdeA, a bacterial acid response chaperone. J Biol Chem 2018; 294:3192-3206. [PMID: 30573682 DOI: 10.1074/jbc.ra118.006398] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 12/17/2018] [Indexed: 11/06/2022] Open
Abstract
The role of protein structural disorder in biological functions has gained increasing attention in the past decade. The bacterial acid-resistant chaperone HdeA belongs to a group of "conditionally disordered" proteins, because it is inactive in its well-structured state and becomes activated via an order-to-disorder transition under acid stress. However, the mechanism for unfolding-induced activation remains unclear because of a lack of experimental information on the unfolded state conformation and the chaperone-client interactions. Herein, we used advanced solution NMR methods to characterize the activated-state conformation of HdeA under acidic conditions and identify its client-binding sites. We observed that the structure of activated HdeA becomes largely disordered and exposes two hydrophobic patches essential for client interactions. Furthermore, using the pH-dependent chemical exchange saturation transfer (CEST) NMR method, we identified three acid-sensitive regions that act as structural locks in regulating the exposure of the two client-binding sites during the activation process, revealing a multistep activation mechanism of HdeA's chaperone function at the atomic level. Our results highlight the role of intrinsic protein disorder in chaperone function and the self-inhibitory role of ordered structures under nonstress conditions, offering new insights for improving our understanding of protein structure-function paradigms.
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Affiliation(s)
- Xing-Chi Yu
- From the College of Chemistry and Molecular Engineering.,Beijing Nuclear Magnetic Resonance Center
| | - Yunfei Hu
- From the College of Chemistry and Molecular Engineering, .,Beijing Nuclear Magnetic Resonance Center
| | - Jienv Ding
- Beijing Nuclear Magnetic Resonance Center.,College of Life Sciences
| | - Hongwei Li
- From the College of Chemistry and Molecular Engineering.,Beijing Nuclear Magnetic Resonance Center
| | - Changwen Jin
- From the College of Chemistry and Molecular Engineering, .,Beijing Nuclear Magnetic Resonance Center.,College of Life Sciences.,Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
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24
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Miyawaki S, Uemura Y, Hongo K, Kawata Y, Mizobata T. Acid-denatured small heat shock protein HdeA from Escherichia coli forms reversible fibrils with an atypical secondary structure. J Biol Chem 2018; 294:1590-1601. [PMID: 30530490 DOI: 10.1074/jbc.ra118.005611] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 12/06/2018] [Indexed: 12/13/2022] Open
Abstract
The periplasmic small heat shock protein HdeA from Escherichia coli is inactive under normal growth conditions (at pH 7) and activated only when E. coli cells are subjected to a sudden decrease in pH, converting HdeA into an acid-denatured active state. Here, using in vitro fibrillation assays, transmission EM, atomic-force microscopy, and CD analyses, we found that when HdeA is active as a molecular chaperone, it is also capable of forming inactive aggregates that, at first glance, resemble amyloid fibrils. We noted that the molecular chaperone activity of HdeA takes precedence over fibrillogenesis under acidic conditions, as the presence of denatured substrate protein was sufficient to suppress HdeA fibril formation. Further experiments suggested that the secondary structure of HdeA fibrils deviates somewhat from typical amyloid fibrils and contains α-helices. Strikingly, HdeA fibrils that formed at pH 2 were immediately resolubilized by a simple shift to pH 7 and from there could regain molecular chaperone activity upon a return to pH 1. HdeA, therefore, provides an unusual example of a "reversible" form of protein fibrillation with an atypical secondary structure composition. The competition between active assistance of denatured polypeptides (its "molecular chaperone" activity) and the formation of inactive fibrillary deposits (its "fibrillogenic" activity) provides a unique opportunity to probe the relationship among protein function, structure, and aggregation in detail.
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Affiliation(s)
- Shiori Miyawaki
- Graduate School of Sustainability Science, Tottori University, Tottori 680-8552, Japan
| | - Yumi Uemura
- Department of Engineering, Tottori University, Tottori 680-8552, Japan
| | - Kunihiro Hongo
- Graduate School of Sustainability Science, Tottori University, Tottori 680-8552, Japan; Department of Engineering, Tottori University, Tottori 680-8552, Japan; Center for Research on Green Sustainable Chemistry, Tottori University, Tottori 680-8552, Japan
| | - Yasushi Kawata
- Graduate School of Sustainability Science, Tottori University, Tottori 680-8552, Japan; Department of Engineering, Tottori University, Tottori 680-8552, Japan; Center for Research on Green Sustainable Chemistry, Tottori University, Tottori 680-8552, Japan
| | - Tomohiro Mizobata
- Graduate School of Sustainability Science, Tottori University, Tottori 680-8552, Japan; Department of Engineering, Tottori University, Tottori 680-8552, Japan; Center for Research on Green Sustainable Chemistry, Tottori University, Tottori 680-8552, Japan.
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25
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Stull F, Hipp H, Stockbridge RB, Bardwell JCA. In vivo chloride concentrations surge to proteotoxic levels during acid stress. Nat Chem Biol 2018; 14:1051-1058. [PMID: 30323217 PMCID: PMC6193267 DOI: 10.1038/s41589-018-0143-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 08/29/2018] [Indexed: 11/23/2022]
Abstract
To successfully colonize the intestine, bacteria must survive passage through the stomach. The permeability of the outer membrane renders the periplasm of Gram-negative bacteria vulnerable to stomach acid, which inactivates proteins. Here we report that the semipermeable nature of the outer membrane allows the development of a strong Donnan equilibrium across this barrier at low pH. As a result, when bacteria are exposed to conditions that mimic gastric juice, periplasmic chloride concentrations rise to levels that exceed 0.6 M. At these chloride concentrations, proteins readily aggregate in vitro. The acid sensitivity of strains lacking acid-protective chaperones is enhanced by chloride, suggesting that these chaperones protect periplasmic proteins both from acidification and from the accompanying accumulation of chloride. These results illustrate how organisms have evolved chaperones to respond to the substantial chemical threat imposed by otherwise innocuous chloride concentrations that are amplified to proteotoxic levels by low-pH-induced Donnan equilibrium effects.
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Affiliation(s)
- Frederick Stull
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA.
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
| | - Hannah Hipp
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Randy B Stockbridge
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI, USA
| | - James C A Bardwell
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA.
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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26
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Kim DH, Han KH. PreSMo Target-Binding Signatures in Intrinsically Disordered Proteins. Mol Cells 2018; 41:889-899. [PMID: 30352491 PMCID: PMC6199570 DOI: 10.14348/molcells.2018.0192] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 08/07/2018] [Accepted: 08/22/2018] [Indexed: 12/26/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) are highly unorthodox proteins that do not form three-dimensional structures under physiological conditions. The discovery of IDPs has destroyed the classical structure-function paradigm in protein science, 3-D structure = function, because IDPs even without well-folded 3-D structures are still capable of performing important biological functions and furthermore are associated with fatal diseases such as cancers, neurodegenerative diseases and viral pandemics. Pre-structured motifs (PreSMos) refer to transient local secondary structural elements present in the target-unbound state of IDPs. During the last two decades PreSMos have been steadily acknowledged as the critical determinants for target binding in dozens of IDPs. To date, the PreSMo concept provides the most convincing structural rationale explaining the IDP-target binding behavior at an atomic resolution. Here we present a brief developmental history of PreSMos and describe their common characteristics. We also provide a list of newly discovered PreSMos along with their functional relevance.
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Affiliation(s)
- Do-Hyoung Kim
- Genome Editing Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141,
Korea
| | - Kyou-Hoon Han
- Genome Editing Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141,
Korea
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27
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Fu X, Wang Y, Shao H, Ma J, Song X, Zhang M, Chang Z. DegP functions as a critical protease for bacterial acid resistance. FEBS J 2018; 285:3525-3538. [DOI: 10.1111/febs.14627] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 06/03/2018] [Accepted: 08/03/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Xinmiao Fu
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation College of Life Sciences Fujian Normal University Fuzhou City Fujian Province China
- State Key Laboratory of Protein and Plant Gene Research School of Life Sciences Peking University Beijing China
- Engineering Research Center of Industrial Microbiology of Ministry of Education College of Life Sciences Fujian Normal University Fuzhou City Fujian Province China
| | - Yan Wang
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation College of Life Sciences Fujian Normal University Fuzhou City Fujian Province China
- State Key Laboratory of Protein and Plant Gene Research School of Life Sciences Peking University Beijing China
- Engineering Research Center of Industrial Microbiology of Ministry of Education College of Life Sciences Fujian Normal University Fuzhou City Fujian Province China
| | - Heqi Shao
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation College of Life Sciences Fujian Normal University Fuzhou City Fujian Province China
| | - Jing Ma
- State Key Laboratory of Protein and Plant Gene Research School of Life Sciences Peking University Beijing China
| | - Xinwen Song
- State Key Laboratory of Protein and Plant Gene Research School of Life Sciences Peking University Beijing China
| | - Meng Zhang
- State Key Laboratory of Protein and Plant Gene Research School of Life Sciences Peking University Beijing China
| | - Zengyi Chang
- State Key Laboratory of Protein and Plant Gene Research School of Life Sciences Peking University Beijing China
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28
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Zhou HX, Pang X. Electrostatic Interactions in Protein Structure, Folding, Binding, and Condensation. Chem Rev 2018; 118:1691-1741. [PMID: 29319301 DOI: 10.1021/acs.chemrev.7b00305] [Citation(s) in RCA: 477] [Impact Index Per Article: 79.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Charged and polar groups, through forming ion pairs, hydrogen bonds, and other less specific electrostatic interactions, impart important properties to proteins. Modulation of the charges on the amino acids, e.g., by pH and by phosphorylation and dephosphorylation, have significant effects such as protein denaturation and switch-like response of signal transduction networks. This review aims to present a unifying theme among the various effects of protein charges and polar groups. Simple models will be used to illustrate basic ideas about electrostatic interactions in proteins, and these ideas in turn will be used to elucidate the roles of electrostatic interactions in protein structure, folding, binding, condensation, and related biological functions. In particular, we will examine how charged side chains are spatially distributed in various types of proteins and how electrostatic interactions affect thermodynamic and kinetic properties of proteins. Our hope is to capture both important historical developments and recent experimental and theoretical advances in quantifying electrostatic contributions of proteins.
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Affiliation(s)
- Huan-Xiang Zhou
- Department of Chemistry and Department of Physics, University of Illinois at Chicago , Chicago, Illinois 60607, United States.,Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
| | - Xiaodong Pang
- Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
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29
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Bai K, Hong B, Hong Z, Sun J, Wang C. Selenium nanoparticles-loaded chitosan/citrate complex and its protection against oxidative stress in D-galactose-induced aging mice. J Nanobiotechnology 2017; 15:92. [PMID: 29262862 PMCID: PMC5738782 DOI: 10.1186/s12951-017-0324-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 11/27/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Selenium (Se) is an indispensable trace element required for animals and humans, and extra Se-supplement is necessary, especially for those having Se deficiency. Recently, selenium nanoparticles (SeNPs), as a special form of Se supplement, have attracted worldwide attention due to their distinguished properties and excellent bioactivities. In this present study, an eco-friendly and economic way to prepare stable SeNPs was introduced. SeNPs were synthesized in the presence of chitosan (CTS) and then embedded into chitosan/citrate gel, generating selenium nanoparticles-loaded chitosan/citrate complex (SeNPs-C/C). Additionally, the clinical potential of SeNPs-C/C was evaluated by using D-galactose (D-gal)-induced aging mice model. RESULTS SeNPs in high uniform with an average diameter of around 50 nm were synthesized in the presence of chitosan, and reversible ionic gelation between chitosan and citrate was utilized to load SeNPs. Subsphaeroidal SeNPs-C/C microspheres of 1-30 μm were obtained by spay-drying. Single SeNPs were physically separated and embedded inside SeNPs-C/C microparticles, with excellent stability and acceptable release. Acute fetal test showed SeNPs-C/C was safer than selenite, with a median lethal dose (LD50) of approximately 4-fold to 11-fold of that of selenite. Oral administration of SeNPs-C/C remarkably retarded the oxidative stress of D-gal in Kunming mice by enhancing the activity of antioxidase, as evidenced by its significant protection of the growth, liver, Se retention and antioxidant bio-markers of mice against D-gal. CONCLUSIONS The design of SeNPs-C/C opens a new path for oral delivery of SeNPs with excellent stability, energy-conservation and environment-friendliness. SeNPs-C/C, as a novel supplement of Se, could be further developed to defend the aging process induced by D-gal.
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Affiliation(s)
- Kaikai Bai
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, 361005, People's Republic of China. .,Engineering Research Center of Marine Biological Resource Comprehensive Utilization, State Oceanic Administration, Xiamen, 361005, People's Republic of China.
| | - Bihong Hong
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, 361005, People's Republic of China.,Engineering Research Center of Marine Biological Resource Comprehensive Utilization, State Oceanic Administration, Xiamen, 361005, People's Republic of China
| | - Zhuan Hong
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, 361005, People's Republic of China.,Engineering Research Center of Marine Biological Resource Comprehensive Utilization, State Oceanic Administration, Xiamen, 361005, People's Republic of China
| | - Jipeng Sun
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, 361005, People's Republic of China.,Engineering Research Center of Marine Biological Resource Comprehensive Utilization, State Oceanic Administration, Xiamen, 361005, People's Republic of China
| | - Changsen Wang
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, 361005, People's Republic of China
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30
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Yu XC, Yang C, Ding J, Niu X, Hu Y, Jin C. Characterizations of the Interactions between Escherichia coli Periplasmic Chaperone HdeA and Its Native Substrates during Acid Stress. Biochemistry 2017; 56:5748-5757. [PMID: 29016106 DOI: 10.1021/acs.biochem.7b00724] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The bacterial acid-resistant chaperone HdeA is a "conditionally disordered" protein that functions at low pH when it undergoes a transition from a well-folded dimer to an unfolded monomer. The dimer dissociation and unfolding processes result in exposure of hydrophobic surfaces that allows binding to a broad range of client proteins. To fully elucidate the chaperone mechanism of HdeA, it is crucial to understand how the activated HdeA interacts with its native substrates during acid stress. Herein, we present a nuclear magnetic resonance study of the pH-dependent HdeA-substrate interactions. Our results show that the activation of HdeA is not only induced by acidification but also regulated by the presence of unfolded substrates. The variable extent of unfolding of substrates differentially regulates the HdeA-substrate interaction, and the binding further affects the HdeA conformation. Finally, we show that HdeA binds its substrates heterogeneously, and the "amphiphilic" model for HdeA-substrate interaction is discussed.
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Affiliation(s)
- Xing-Chi Yu
- College of Chemistry and Molecular Engineering, ‡Beijing Nuclear Magnetic Resonance Center, §College of Life Sciences, and ∥Beijing National Laboratory for Molecular Sciences, Peking University , Beijing 100871, China
| | - Chengfeng Yang
- College of Chemistry and Molecular Engineering, ‡Beijing Nuclear Magnetic Resonance Center, §College of Life Sciences, and ∥Beijing National Laboratory for Molecular Sciences, Peking University , Beijing 100871, China
| | - Jienv Ding
- College of Chemistry and Molecular Engineering, ‡Beijing Nuclear Magnetic Resonance Center, §College of Life Sciences, and ∥Beijing National Laboratory for Molecular Sciences, Peking University , Beijing 100871, China
| | - Xiaogang Niu
- College of Chemistry and Molecular Engineering, ‡Beijing Nuclear Magnetic Resonance Center, §College of Life Sciences, and ∥Beijing National Laboratory for Molecular Sciences, Peking University , Beijing 100871, China
| | - Yunfei Hu
- College of Chemistry and Molecular Engineering, ‡Beijing Nuclear Magnetic Resonance Center, §College of Life Sciences, and ∥Beijing National Laboratory for Molecular Sciences, Peking University , Beijing 100871, China
| | - Changwen Jin
- College of Chemistry and Molecular Engineering, ‡Beijing Nuclear Magnetic Resonance Center, §College of Life Sciences, and ∥Beijing National Laboratory for Molecular Sciences, Peking University , Beijing 100871, China
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31
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Yang Y, Song H, He D, Zhang S, Dai S, Xie X, Lin S, Hao Z, Zheng H, Chen PR. Genetically encoded releasable photo-cross-linking strategies for studying protein–protein interactions in living cells. Nat Protoc 2017; 12:2147-2168. [DOI: 10.1038/nprot.2017.090] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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32
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Voth W, Jakob U. Stress-Activated Chaperones: A First Line of Defense. Trends Biochem Sci 2017; 42:899-913. [PMID: 28893460 DOI: 10.1016/j.tibs.2017.08.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/18/2017] [Accepted: 08/21/2017] [Indexed: 10/18/2022]
Abstract
Proteins are constantly challenged by environmental stress conditions that threaten their structure and function. Especially problematic are oxidative, acid, and severe heat stress which induce very rapid and widespread protein unfolding and generate conditions that make canonical chaperones and/or transcriptional responses inadequate to protect the proteome. We review here recent advances in identifying and characterizing stress-activated chaperones which are inactive under non-stress conditions but become potent chaperones under specific protein-unfolding stress conditions. We discuss the post-translational mechanisms by which these chaperones sense stress, and consider the role that intrinsic disorder plays in their regulation and function. We examine their physiological roles under both non-stress and stress conditions, their integration into the cellular proteostasis network, and their potential as novel therapeutic targets.
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Affiliation(s)
- Wilhelm Voth
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular Biology, Universitätsmedizin Göttingen, 37073 Göttingen, Germany
| | - Ursula Jakob
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
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33
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Natarajan J, Madras G, Chatterjee K. Poly(ester amide)s from Poly(ethylene terephthalate) Waste for Enhancing Bone Regeneration and Controlled Release. ACS APPLIED MATERIALS & INTERFACES 2017; 9:28281-28297. [PMID: 28766935 DOI: 10.1021/acsami.7b09299] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The present study elucidates the facile synthesis and exceptional properties of a family of novel poly(ester amide)s (PEAs) based on bis(2-hydroxy ethylene) terephthalamide that was obtained from the poly(ethylene terephthalate) waste. Fourier transform infrared and 1H NMR were used to verify the presence of ester and amide in the polymer backbone. Differential scanning calorimetry data showed that the glass transition temperature decreased with as the chain length of dicarboxylic acids increased. Dynamic mechanical analysis and contact angle studies proved that the modulus values and hydrophobicity increased with as the chain lengths of dicarboxylic acids increased. In vitro hydrolytic degradation and dye release studies demonstrated that the degradation and release decreased with as the chain lengths of dicarboxylic acids increased. Modeling these data illustrated that degradation and release follow first-order degradation and zero-order release, respectively. The in vitro cytocompatibility studies confirmed the minimal toxicity characteristic of these polymers. Osteogenic studies proved that these polymers can be highly influential in diverting the cells toward osteogenic lineage. Alizarin red staining evinced the presence of twice the amount of calcium phosphate deposits by the cells on these polymers when compared to the control. The observed result was also corroborated by the increased expression of alkaline phosphatase. These findings were further validated by the markedly higher mRNA expressions for known osteogenic markers using real time polymerase chain reaction. Therefore, these polymers efficiently promoted osteogenesis. This study demonstrates that the physical properties, degradation, and release kinetics can be altered to meet the specific requirements in organ regeneration as well as facilitate simultaneous polymer resorption through control of the chain length of the monomers. The findings of this study have significant implications for designing cost-effective biodegradable polymers for tissue engineering.
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Affiliation(s)
- Janeni Natarajan
- Centre for Nano Science and Engineering, ‡Department of Chemical Engineering, and §Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
| | - Giridhar Madras
- Centre for Nano Science and Engineering, ‡Department of Chemical Engineering, and §Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
| | - Kaushik Chatterjee
- Centre for Nano Science and Engineering, ‡Department of Chemical Engineering, and §Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
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34
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Zhang S, He D, Lin Z, Yang Y, Song H, Chen PR. Conditional Chaperone-Client Interactions Revealed by Genetically Encoded Photo-cross-linkers. Acc Chem Res 2017; 50:1184-1192. [PMID: 28467057 DOI: 10.1021/acs.accounts.6b00647] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The cell envelope is an integral and essential component of Gram-negative bacteria. As the front line during host-pathogen interactions, it is directly challenged by host immune responses as well as other harsh extracellular stimuli. The high permeability of the outer-membrane and the lack of ATP energy system render it difficult to maintain important biological activities within the periplasmic space under stress conditions. The HdeA/B chaperone machinery is the only known acid resistant system found in bacterial periplasm, enabling enteric pathogens to survive through the highly acidic human stomach and establish infections in the intestine. These two homologous chaperones belong to a fast growing family of conditionally disordered chaperones that conditionally lose their well-defined three-dimensional structures to exert biological activities. Upon losing ordered structures, these proteins commit promiscuous binding of diverse clients in response to environmental stimulation. For example, HdeA and HdeB are well-folded inactive dimers at neutral pH but become partially unfolded to protect a wide array of acid-denatured proteins upon acid stress. Whether these conditionally disordered chaperones possess client specificities remains unclear. This is in part due to the lack of efficient tools to investigate such versatile and heterogeneous protein-protein interactions under living conditions. Genetically encoded protein photo-cross-linkers have offered a powerful strategy to capture protein-protein interactions, showing great potential in profiling protein interaction networks, mapping binding interfaces, and probing dynamic changes in both physiological and pathological settings. Despite great success, photo-cross-linkers that can simultaneously capture the promiscuous binding partners and directly identify the interaction interfaces remain technically challenging. Furthermore, methods for side-by-side profiling and comparing the condition-dependent client pools from two homologous chaperones are lacking. Herein, we introduce our recent efforts in developing a panel of versatile genetically encoded photo-cross-linkers to study the disorder-mediated chaperone-client interactions in living cells. In particular, we have developed a series of proteomic-based strategies relying on these new photo-cross-linkers to systematically compare the client profiles of HdeA and HdeB, as well as to map their interaction interfaces. These studies revealed the mode-of-action, particularly the client specificity, of these two conditionally disordered chaperones. In the end, some recent elegant work from other groups that applied the genetically encoded photo-cross-linking strategy to illuminate important protein-protein interactions within bacterial cell envelope is also discussed.
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Affiliation(s)
- Shuai Zhang
- Beijing National
Laboratory for Molecular Sciences, Synthetic and Functional Biomolecules
Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Dan He
- Beijing National
Laboratory for Molecular Sciences, Synthetic and Functional Biomolecules
Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Zhi Lin
- Beijing National
Laboratory for Molecular Sciences, Synthetic and Functional Biomolecules
Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Yi Yang
- Beijing National
Laboratory for Molecular Sciences, Synthetic and Functional Biomolecules
Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Haiping Song
- Beijing National
Laboratory for Molecular Sciences, Synthetic and Functional Biomolecules
Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Peng R. Chen
- Beijing National
Laboratory for Molecular Sciences, Synthetic and Functional Biomolecules
Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking-Tsinghua Center for Life Sciences, Beijing 100871, China
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35
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Bose D, Patra M, Chakrabarti A. Effect of pH on stability, conformation, and chaperone activity of erythroid & non-erythroid spectrin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:694-702. [PMID: 28373029 DOI: 10.1016/j.bbapap.2017.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 03/28/2017] [Accepted: 03/30/2017] [Indexed: 11/29/2022]
Abstract
Spectrin, a major component of the eukaryotic membrane skeleton, has been shown to have chaperone like activity. Here we investigate the pH induced changes in the structure and stability of erythroid and brain spectrin by spectroscopic methods. We also correlate these changes with modulations of chaperone potential at different pH. We have followed the pH induced structural changes by circular dichroism spectroscopy and intrinsic tryptophan fluorescence. It is seen that lowering the pH from 9 has little effect on structure of the proteins till about pH6. At pH4, there is significant change of the secondary structure of the proteins, along with a 5nm hypsochromic shift of the emission maxima. Below pH4 the proteins undergo acid denaturation. Probing exposed hydrophobic patches on the proteins using protein-bound 8-anilinonaphthalene-1-sulfonate fluorescence demonstrates that there is higher solvent accessibility of hydrophobic surfaces in both forms of spectrin at around pH4. Dynamic light scattering and 90° light scattering studies show that the both forms of spectrin forms oligomers at pH~4. Chemical unfolding data shows that these oligomers are less stable than the tetrameric form. Aggregation studies with BSA show that at pH4, both spectrins exhibit better chaperone activity. This enhancement of chaperone like activity appears to result from an increase in regions of solvent-exposed hydrophobicity and oligomeric state of the spectrins which in turn are induced by moderately acid pH. This may have in-vivo implications in cells facing stress conditions where cytoplasmic pH is lowered.
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Affiliation(s)
- Dipayan Bose
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, HBNI, Kolkata, India
| | - Malay Patra
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, HBNI, Kolkata, India
| | - Abhijit Chakrabarti
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, HBNI, Kolkata, India.
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36
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Qi Z, Chen Y. Charge-transfer-based terbium MOF nanoparticles as fluorescent pH sensor for extreme acidity. Biosens Bioelectron 2017; 87:236-241. [DOI: 10.1016/j.bios.2016.08.052] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/08/2016] [Accepted: 08/17/2016] [Indexed: 02/07/2023]
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37
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Socher E, Sticht H. Probing the Structure of the Escherichia coli Periplasmic Proteins HdeA and YmgD by Molecular Dynamics Simulations. J Phys Chem B 2016; 120:11845-11855. [PMID: 27787971 DOI: 10.1021/acs.jpcb.6b06091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
HdeA and YmgD are structurally homologous proteins in the periplasm of Escherichia coli. HdeA has been shown to represent an acid-activated chaperone, whereas the function of YmgD has not yet been characterized. We performed pH-titrating molecular dynamics simulations (pHtMD) to investigate the structural changes of both proteins and to assess whether YmgD may also exhibit an unfolding behavior similar to that of HdeA. The unfolding pathway of HdeA includes partially unfolded dimer structures, which represent a prerequisite for subsequent dissociation. In contrast to the coupled unfolding and dissociation of HdeA, YmgD displays dissociation of the folded subunits, and the subunits do not undergo significant unfolding even at low pH values. The differences in subunit stability between HdeA and YmgD may be explained by the structural features of helix D, which represents the starting point of unfolding in HdeA. In summary, the present study suggests that YmgD either is not an acid-activated chaperone or, at least, does not require unfolding for activation.
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Affiliation(s)
- Eileen Socher
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) , Fahrstraße 17, 91054 Erlangen, Germany
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) , Fahrstraße 17, 91054 Erlangen, Germany
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38
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Dahl JU, Koldewey P, Bardwell JCA, Jakob U. Detection of the pH-dependent Activity of Escherichia coli Chaperone HdeB In Vitro and In Vivo. J Vis Exp 2016. [PMID: 27805614 DOI: 10.3791/54527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Bacteria are frequently exposed to environmental changes, such as alterations in pH, temperature, redox status, light exposure or mechanical force. Many of these conditions cause protein unfolding in the cell and have detrimental impact on the survival of the organism. A group of unrelated, stress-specific molecular chaperones have been shown to play essential roles in the survival of these stress conditions. While fully folded and chaperone-inactive before stress, these proteins rapidly unfold and become chaperone-active under specific stress conditions. Once activated, these conditionally disordered chaperones bind to a large number of different aggregation-prone proteins, prevent their aggregation and either directly or indirectly facilitate protein refolding upon return to non-stress conditions. The primary approach for gaining a more detailed understanding about the mechanism of their activation and client recognition involves the purification and subsequent characterization of these proteins using in vitro chaperone assays. Follow-up in vivo stress assays are absolutely essential to independently confirm the obtained in vitro results. This protocol describes in vitro and in vivo methods to characterize the chaperone activity of E. coli HdeB, an acid-activated chaperone. Light scattering measurements were used as a convenient read-out for HdeB's capacity to prevent acid-induced aggregation of an established model client protein, MDH, in vitro. Analytical ultracentrifugation experiments were applied to reveal complex formation between HdeB and its client protein LDH, to shed light into the fate of client proteins upon their return to non-stress conditions. Enzymatic activity assays of the client proteins were conducted to monitor the effects of HdeB on pH-induced client inactivation and reactivation. Finally, survival studies were used to monitor the influence of HdeB's chaperone function in vivo.
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Affiliation(s)
- Jan-Ulrik Dahl
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan;
| | - Philipp Koldewey
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan; Howard Hughes Medical Institute, University of Michigan
| | - James C A Bardwell
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan; Howard Hughes Medical Institute, University of Michigan;
| | - Ursula Jakob
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan
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39
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Natarajan J, Dasgupta Q, Shetty SN, Sarkar K, Madras G, Chatterjee K. Poly(ester amide)s from Soybean Oil for Modulated Release and Bone Regeneration. ACS APPLIED MATERIALS & INTERFACES 2016; 8:25170-84. [PMID: 27599306 DOI: 10.1021/acsami.6b10382] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Designing biomaterials for bone tissue regeneration that are also capable of eluting drugs is challenging. Poly(ester amide)s are known for their commendable mechanical properties, degradation, and cellular response. In this regard, development of new poly(ester amide)s becomes imperative to improve the quality of lives of people affected by bone disorders. In this framework, a family of novel soybean oil based biodegradable poly(ester amide)s was synthesized based on facile catalyst-free melt-condensation reaction. The structure of the polymers was confirmed by FTIR and (1)H -NMR, which indicated the formation of the ester and amide bonds along the polymer backbone. Thermal analysis revealed the amorphous nature of the polymers. Contact angle and swelling studies proved that the hydrophobic nature increased with increase in chain length of the diacids and decreased with increase in molar ratio of sebacic acid. Mechanical studies proved that Young's modulus decreased with decrease in chain lengths of the diacids and increase in molar ratio of sebacic acid. The in vitro hydrolytic degradation and dye release demonstrated that the degradation and release decreased with increase in chain lengths of the diacids and increased with increase in molar ratio of sebacic acid. The degradation followed first order kinetics and dye release followed Higuchi kinetics. In vitro cell studies showed no toxic effects of the polymers. Osteogenesis studies revealed that the polymers can be remarkably efficient because more than twice the amount of minerals were deposited on the polymer surfaces than on the tissue culture polystyrene surfaces. Thus, a family of novel poly(ester amide)s has been synthesized, characterized for controlled release and tissue engineering applications wherein the physical, degradation, and release kinetics can be tuned by varying the monomers and their molar ratios.
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Affiliation(s)
- Janeni Natarajan
- Centre for Nano Science and Engineering, ‡Centre for Biosystems Science and Engineering, §Department of Chemical Engineering, and ∥Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
| | - Queeny Dasgupta
- Centre for Nano Science and Engineering, ‡Centre for Biosystems Science and Engineering, §Department of Chemical Engineering, and ∥Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
| | - Shreya N Shetty
- Centre for Nano Science and Engineering, ‡Centre for Biosystems Science and Engineering, §Department of Chemical Engineering, and ∥Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
| | - Kishor Sarkar
- Centre for Nano Science and Engineering, ‡Centre for Biosystems Science and Engineering, §Department of Chemical Engineering, and ∥Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
| | - Giridhar Madras
- Centre for Nano Science and Engineering, ‡Centre for Biosystems Science and Engineering, §Department of Chemical Engineering, and ∥Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
| | - Kaushik Chatterjee
- Centre for Nano Science and Engineering, ‡Centre for Biosystems Science and Engineering, §Department of Chemical Engineering, and ∥Department of Materials Engineering, Indian Institute of Science , Bangalore 560012, India
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40
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Yang Y, Song H, Chen PR. Genetically encoded photocrosslinkers for identifying and mapping protein-protein interactions in living cells. IUBMB Life 2016; 68:879-886. [DOI: 10.1002/iub.1560] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 09/03/2016] [Indexed: 12/12/2022]
Affiliation(s)
- Yi Yang
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University; Beijing China
| | - Haiping Song
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University; Beijing China
| | - Peng R. Chen
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University; Beijing China
- Peking-Tsinghua Center for Life Sciences; Beijing China
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41
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Wang X, Jiang F, Zheng J, Chen L, Dong J, Sun L, Zhu Y, Liu B, Yang J, Yang G, Jin Q. The outer membrane phospholipase A is essential for membrane integrity and type III secretion in Shigella flexneri. Open Biol 2016; 6:rsob.160073. [PMID: 27655730 PMCID: PMC5043575 DOI: 10.1098/rsob.160073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 08/31/2016] [Indexed: 12/11/2022] Open
Abstract
Outer membrane phospholipase A (OMPLA) is an enzyme located in the outer membrane of Gram-negative bacteria. OMPLA exhibits broad substrate specificity, and some of its substrates are located in the cellular envelope. Generally, the enzymatic activity can only be induced by perturbation of the cell envelope integrity through diverse methods. Although OMPLA has been thoroughly studied as a membrane protein in Escherichia coli and is constitutively expressed in many other bacterial pathogens, little is known regarding the functions of OMPLA during the process of bacterial infection. In this study, the proteomic and transcriptomic data indicated that OMPLA in Shigella flexneri, termed PldA, both stabilizes the bacterial membrane and is involved in bacterial infection under ordinary culture conditions. A series of physiological assays substantiated the disorganization of the bacterial outer membrane and the periplasmic space in the ΔpldA mutant strain. Furthermore, the ΔpldA mutant strain showed decreased levels of type III secretion system expression, contributing to the reduced internalization efficiency in host cells. The results of this study support that PldA, which is widespread across Gram-negative bacteria, is an important factor for the bacterial life cycle, particularly in human pathogens.
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Affiliation(s)
- Xia Wang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Feng Jiang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Jianhua Zheng
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Lihong Chen
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Jie Dong
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Lilian Sun
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Yafang Zhu
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Bo Liu
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Jian Yang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Guowei Yang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
| | - Qi Jin
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, People's Republic of China
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42
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Yang Y, Song H, He D, Zhang S, Dai S, Lin S, Meng R, Wang C, Chen PR. Genetically encoded protein photocrosslinker with a transferable mass spectrometry-identifiable label. Nat Commun 2016; 7:12299. [PMID: 27460181 PMCID: PMC4974458 DOI: 10.1038/ncomms12299] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 06/16/2016] [Indexed: 11/10/2022] Open
Abstract
Coupling photocrosslinking reagents with mass spectrometry has become a powerful tool for studying protein–protein interactions in living systems, but it still suffers from high rates of false-positive identifications as well as the lack of information on interaction interface due to the challenges in deciphering crosslinking peptides. Here we develop a genetically encoded photo-affinity unnatural amino acid that introduces a mass spectrometry-identifiable label (MS-label) to the captured prey proteins after photocrosslinking and prey–bait separation. This strategy, termed IMAPP (In-situ cleavage and MS-label transfer After Protein Photocrosslinking), enables direct identification of photo-captured substrate peptides that are difficult to uncover by conventional genetically encoded photocrosslinkers. Taking advantage of the MS-label, the IMAPP strategy significantly enhances the confidence for identifying protein–protein interactions and enables simultaneous mapping of the binding interface under living conditions. Mapping protein-protein interaction using crosslinking and mass spectroscopy strategies is hampered by a high rate of false-positive results. Here, the authors develop a genetically encoded photo-affinity probe for accurate identification of protein interaction partners and crosslinking sites.
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Affiliation(s)
- Yi Yang
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Haiping Song
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Dan He
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Shuai Zhang
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Shizhong Dai
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Shixian Lin
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Rong Meng
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Chu Wang
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Peking-Tsinghua Center for Life Sciences, Beijing 100871, China
| | - Peng R Chen
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Peking-Tsinghua Center for Life Sciences, Beijing 100871, China
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43
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Kumar CS, Swamy MJ. A pH Switch Regulates the Inverse Relationship between Membranolytic and Chaperone-like Activities of HSP-1/2, a Major Protein of Horse Seminal Plasma. Biochemistry 2016; 55:3650-7. [DOI: 10.1021/acs.biochem.5b01374] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- C. Sudheer Kumar
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Musti J. Swamy
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
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44
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Dickson A, Ahlstrom LS, Brooks CL. Coupled folding and binding with 2D Window-Exchange Umbrella Sampling. J Comput Chem 2016; 37:587-94. [PMID: 26250657 PMCID: PMC4744578 DOI: 10.1002/jcc.24004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 05/18/2015] [Accepted: 05/27/2015] [Indexed: 12/31/2022]
Abstract
Intrinsically disordered regions of proteins can gain structure by binding to a partner. This process, of coupled folding and binding (CFaB), is a fundamental part of many important biological processes. Structure-based models have proven themselves capable of revealing fundamental aspects of how CFaB occurs, however, typical methods to enhance the sampling of these transitions, such as replica exchange, do not adequately sample the transition state region of this extremely rare process. Here, we use a variant of Umbrella Sampling to enforce sampling of the transition states of CFaB of HdeA monomers at neutral pH, an extremely rare process that occurs over timescales ranging from seconds to hours. Using high resolution sampling in the transition state region, we cluster states along the principal transition path to obtain a detailed description of coupled binding and folding for the HdeA dimer, revealing new insight into the ensemble of states that are accessible to client recognition. We then demonstrate that exchanges between umbrella sampling windows, as done in previous work, significantly improve relaxation in variables orthogonal to the restraints used. Altogether, these results show that Window-Exchange Umbrella Sampling is a promising approach for systems that exhibit flexible binding, and can reveal transition state ensembles of these systems in high detail. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Alex Dickson
- Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109
| | - Logan S. Ahlstrom
- Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109
| | - Charles L. Brooks
- Biophysics Program, The University of Michigan, Ann Arbor, MI 48109 and Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109
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45
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Mimicking titration experiments with MD simulations: A protocol for the investigation of pH-dependent effects on proteins. Sci Rep 2016; 6:22523. [PMID: 26936826 PMCID: PMC4776130 DOI: 10.1038/srep22523] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 02/15/2016] [Indexed: 11/08/2022] Open
Abstract
Protein structure and function are highly dependent on the environmental pH. However, the temporal or spatial resolution of experimental approaches hampers direct observation of pH-induced conformational changes at the atomic level. Molecular dynamics (MD) simulation strategies (e.g. constant pH MD) have been developed to bridge this gap. However, one frequent problem is the sampling of unrealistic conformations, which may also lead to poor pKa predictions. To address this problem, we have developed and benchmarked the pH-titration MD (pHtMD) approach, which is inspired by wet-lab titration experiments. We give several examples how the pHtMD protocol can be applied for pKa calculation including peptide systems, Staphylococcus nuclease (SNase), and the chaperone HdeA. For HdeA, pHtMD is also capable of monitoring pH-dependent dimer dissociation in accordance with experiments. We conclude that pHtMD represents a versatile tool for pKa value calculation and simulation of pH-dependent effects in proteins.
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46
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Natarajan J, Madras G, Chatterjee K. Localized delivery and enhanced osteogenic differentiation with biodegradable galactitol polyester elastomers. RSC Adv 2016. [DOI: 10.1039/c6ra11476h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cytocompatible galactitol based polyesters showed variations in physical properties, degradation, dye release and ability to direct cells towards bone lineage.
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Affiliation(s)
- Janeni Natarajan
- Centre for Nano Science and Engineering
- Indian Institute of Science
- Bangalore-560012
- India
| | - Giridhar Madras
- Department of Chemical Engineering
- Indian Institute of Science
- Bangalore-560012
- India
| | - Kaushik Chatterjee
- Department of Materials Engineering
- Indian Institute of Science
- Bangalore-560012
- India
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47
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Zhai Z, Wu Q, Zheng W, Liu M, Pielak GJ, Li C. Roles of structural plasticity in chaperone HdeA activity are revealed by 19F NMR. Chem Sci 2015; 7:2222-2228. [PMID: 29910910 PMCID: PMC5975942 DOI: 10.1039/c5sc04297f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 11/30/2015] [Indexed: 11/21/2022] Open
Abstract
Multiple conformations of acid chaperone HdeA and their roles in activity.
HdeA, a minimal ATP-independent acid chaperone, is crucial for the survival of enteric pathogens as they transit the acidic (pH 1–3) environment of the stomach. Although protein disorder (unfolding) and structural plasticity have been elegantly linked to HdeA function, the details of the linkage are lacking. Here, we apply 19F NMR to reveal the structural transition associated with activation. We find that unfolding is necessary but not sufficient for activation. Multiple conformations are present in the functional state at low pH, but the partially folded conformation is essential for HdeA chaperone activity, and HdeA's intrinsic disulfide bond is required to maintain the partially folded conformation. The results show that both disorder and order are key to function. The ability of 19F NMR to reveal and quantify multiple conformational states makes it a powerful tool for studying other chaperones.
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Affiliation(s)
- Zining Zhai
- Key Laboratory of Magnetic Resonance in Biological Systems , State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics , National Center for Magnetic Resonance in Wuhan , Wuhan Institute of Physics and Mathematics , Chinese Academy of Sciences , Wuhan , P. R. China . .,University of Chinese Academy of Sciences , Beijing , P. R. China
| | - Qiong Wu
- Key Laboratory of Magnetic Resonance in Biological Systems , State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics , National Center for Magnetic Resonance in Wuhan , Wuhan Institute of Physics and Mathematics , Chinese Academy of Sciences , Wuhan , P. R. China .
| | - Wenwen Zheng
- Key Laboratory of Magnetic Resonance in Biological Systems , State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics , National Center for Magnetic Resonance in Wuhan , Wuhan Institute of Physics and Mathematics , Chinese Academy of Sciences , Wuhan , P. R. China . .,University of Chinese Academy of Sciences , Beijing , P. R. China
| | - Maili Liu
- Key Laboratory of Magnetic Resonance in Biological Systems , State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics , National Center for Magnetic Resonance in Wuhan , Wuhan Institute of Physics and Mathematics , Chinese Academy of Sciences , Wuhan , P. R. China .
| | - Gary J Pielak
- Department of Chemistry and Department of Biochemistry and Biophysics , University of North Carolina , Chapel Hill , NC , USA.,Lineberger Comprehensive Cancer Center , University of North Carolina , Chapel Hill , NC , USA
| | - Conggang Li
- Key Laboratory of Magnetic Resonance in Biological Systems , State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics , National Center for Magnetic Resonance in Wuhan , Wuhan Institute of Physics and Mathematics , Chinese Academy of Sciences , Wuhan , P. R. China .
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48
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Ding J, Yang C, Niu X, Hu Y, Jin C. HdeB chaperone activity is coupled to its intrinsic dynamic properties. Sci Rep 2015; 5:16856. [PMID: 26593705 PMCID: PMC4655364 DOI: 10.1038/srep16856] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 10/21/2015] [Indexed: 11/09/2022] Open
Abstract
Enteric bacteria encounter extreme acidity when passing through hosts' stomach. Since the bacterial periplasmic space quickly equilibrates with outer environment, an efficient acid resistance mechanism is essential in preventing irreversible protein denaturation/aggregation and maintaining bacteria viability. HdeB, along with its homolog HdeA, was identified as a periplasmic acid-resistant chaperone. Both proteins exist as homodimers and share similar monomeric structures under neutral pH, while showing different dimeric packing interfaces. Previous investigations show that HdeA functions through an acid-induced dimer-to-monomer transition and partial unfolding at low pH (pH 2-3), resulting in exposure of hydrophobic surfaces that bind substrate proteins. In contrast, HdeB appears to have a much higher optimal activation pH (pH 4-5), under which condition the protein maintains a well-folded dimer and the mechanism for its chaperone activity remains elusive. Herein, we present an NMR study of HdeB to investigate its dynamic properties. Our results reveal that HdeB undergoes significant micro- to milli-second timescale conformational exchanges at neutral to near-neutral pH, under the later condition it exhibits optimal activity. The current study indicates that HdeB activation is coupled to its intrinsic dynamics instead of structural changes, and therefore its functional mechanism is apparently different from HdeA.
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Affiliation(s)
- Jienv Ding
- College of Life Sciences, Peking University, Beijing 100871, China.,Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing 100871, China
| | - Chengfeng Yang
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing 100871, China
| | - Xiaogang Niu
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing 100871, China
| | - Yunfei Hu
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing 100871, China
| | - Changwen Jin
- College of Life Sciences, Peking University, Beijing 100871, China.,College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing 100871, China.,Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
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49
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Targeting disordered proteins with small molecules using entropy. Trends Biochem Sci 2015; 40:491-6. [DOI: 10.1016/j.tibs.2015.07.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 07/06/2015] [Accepted: 07/07/2015] [Indexed: 12/31/2022]
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50
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Choi JH, Laurent AH, Hilser VJ, Ostermeier M. Design of protein switches based on an ensemble model of allostery. Nat Commun 2015; 6:6968. [PMID: 25902417 PMCID: PMC4704092 DOI: 10.1038/ncomms7968] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 03/17/2015] [Indexed: 02/07/2023] Open
Abstract
Switchable proteins that can be regulated through exogenous or endogenous inputs have a broad range of biotechnological and biomedical applications. Here we describe the design of switchable enzymes based on an ensemble allosteric model. First, we insert an enzyme domain into an effector-binding domain such that both domains remained functionally intact. Second, we induce the fusion to behave as a switch through the introduction of conditional conformational flexibility designed to increase the conformational entropy of the enzyme domain in a temperature- or pH-dependent fashion. We confirm the switching behaviour in vitro and in vivo. Structural and thermodynamic studies support the hypothesis that switching result from an increase in conformational entropy of the enzyme domain in the absence of effector. These results support the ensemble model of allostery and embody a strategy for the design of protein switches.
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Affiliation(s)
- Jay H Choi
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, 3400N Charles Street, Baltimore, Maryland 21218, USA
| | - Abigail H Laurent
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, 3400N Charles Street, Baltimore, Maryland 21218, USA
| | - Vincent J Hilser
- Department of Biology, Johns Hopkins University, 3400N Charles Street, Baltimore, Maryland 21218, USA
| | - Marc Ostermeier
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, 3400N Charles Street, Baltimore, Maryland 21218, USA
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