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Dong Y, Tang H, Dai H, Zhao H, Wang J. The application of nanodiscs in membrane protein drug discovery & development and drug delivery. Front Chem 2024; 12:1444801. [PMID: 39359422 PMCID: PMC11445163 DOI: 10.3389/fchem.2024.1444801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 09/02/2024] [Indexed: 10/04/2024] Open
Abstract
The phospholipid bilayer nanodiscs (LNDs), as a rapidly-developing tool in recent years, provide a natural bio-memebrane environment to maintain the native conformation and functions of membrane proteins as well as a versatile delivery vehicle for a variety of hydrophobic and hydrophilic drugs. We have seen unprecedented advantages of phospholipid bilayer nanodiscs in membrane protein structure characterization, biochemical and physiological studies of membrane proteins, membrane environment studies, drug discovery & development, and drug delivery. Many previous reviews have been mainly focused on the advantages of nanodiscs in membrane protein researches, but few have touched upon the importance and potential application of nanodiscs in pharmaceutical industries. This review will provide general description of the structural characteristics, advantages, classification, and applications of phospholipid nanodiscs, with particular focus on nanodisc-enabled membrane protein drug discovery & development as well as drug delivery.
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Affiliation(s)
- Yingkui Dong
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
- Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui, China
| | - Huan Tang
- Hefei China Science Longwood Biological Technology Co., Ltd, Hefei, Anhui, China
| | - Han Dai
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Hongxin Zhao
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
- Hefei China Science Longwood Biological Technology Co., Ltd, Hefei, Anhui, China
| | - Junfeng Wang
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
- Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui, China
- University of Science and Technology of China, Hefei, Anhui, China
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Son A, Kim W, Park J, Lee W, Lee Y, Choi S, Kim H. Utilizing Molecular Dynamics Simulations, Machine Learning, Cryo-EM, and NMR Spectroscopy to Predict and Validate Protein Dynamics. Int J Mol Sci 2024; 25:9725. [PMID: 39273672 PMCID: PMC11395565 DOI: 10.3390/ijms25179725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2024] [Revised: 09/06/2024] [Accepted: 09/07/2024] [Indexed: 09/15/2024] Open
Abstract
Protein dynamics play a crucial role in biological function, encompassing motions ranging from atomic vibrations to large-scale conformational changes. Recent advancements in experimental techniques, computational methods, and artificial intelligence have revolutionized our understanding of protein dynamics. Nuclear magnetic resonance spectroscopy provides atomic-resolution insights, while molecular dynamics simulations offer detailed trajectories of protein motions. Computational methods applied to X-ray crystallography and cryo-electron microscopy (cryo-EM) have enabled the exploration of protein dynamics, capturing conformational ensembles that were previously unattainable. The integration of machine learning, exemplified by AlphaFold2, has accelerated structure prediction and dynamics analysis. These approaches have revealed the importance of protein dynamics in allosteric regulation, enzyme catalysis, and intrinsically disordered proteins. The shift towards ensemble representations of protein structures and the application of single-molecule techniques have further enhanced our ability to capture the dynamic nature of proteins. Understanding protein dynamics is essential for elucidating biological mechanisms, designing drugs, and developing novel biocatalysts, marking a significant paradigm shift in structural biology and drug discovery.
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Affiliation(s)
- Ahrum Son
- Department of Molecular Medicine, Scripps Research, San Diego, CA 92037, USA
| | - Woojin Kim
- Department of Bio-AI Convergence, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Jongham Park
- Department of Bio-AI Convergence, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Wonseok Lee
- Department of Bio-AI Convergence, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Yerim Lee
- Department of Bio-AI Convergence, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Seongyun Choi
- Department of Convergent Bioscience and Informatics, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Hyunsoo Kim
- Department of Bio-AI Convergence, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
- Department of Convergent Bioscience and Informatics, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
- Protein AI Design Institute, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
- SCICS, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
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Brahma R, Raghuraman H. Characterization of a novel MgtE homolog and its structural dynamics in membrane mimetics. Biophys J 2024; 123:1968-1983. [PMID: 38042987 PMCID: PMC11309985 DOI: 10.1016/j.bpj.2023.11.3402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 11/03/2023] [Accepted: 11/30/2023] [Indexed: 12/04/2023] Open
Abstract
Magnesium (Mg2+) is the most abundant divalent cation in the cell and is critical for numerous cellular processes. Despite its importance, the mechanisms of intracellular Mg2+ transport and its regulation are poorly understood. MgtE is the main Mg2+ transport system in almost half of bacterial species and is an ortholog of mammalian SLC41A1 transporters, which are implicated in neurodegenerative diseases and cancer. To date, only MgtE from Thermus thermophilus (MgtETT) has been extensively characterized, mostly in detergent micelles, and gating-related structural dynamics in biologically relevant membranes are scarce. The MgtE homolog from Bacillus firmus (MgtEBF) is unique since it lacks the entire Mg2+-sensing N-domain but has conserved structural motifs in the TM-domain for Mg2+ transport. In this work, we have successfully purified this novel homolog in a stable and functional form, and ColabFold structure prediction analysis suggests a homodimer. Further, microscale thermophoresis experiments show that MgtEBF binds Mg2+ and ATP, similar to MgtETT. Importantly, we show that, despite lacking the N-domain, MgtEBF mediates Mg2+ transport function in the presence of an inwardly directed Mg2+ gradient in reconstituted proteoliposomes. Furthermore, comparison of the organization and dynamics of Trp residues in the TM-domain of MgtEBF in membrane mimetics, in apo- and Mg2+-bound forms, suggests that the cytoplasmic binding of Mg2+ might involve modest gating-related conformational changes at the TM-domain. Overall, our results show that the gating-related structural dynamics (hydration dynamics, conformational heterogeneity) of the full-length MgtEBF is significantly changed in functionally pertinent membrane environment, emphasizing the importance of lipid-protein interactions in MgtE gating mechanisms.
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Affiliation(s)
- Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata, India; Homi Bhabha National Institute, Training School Complex, Mumbai, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata, India; Homi Bhabha National Institute, Training School Complex, Mumbai, India.
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Lan T, Dong Y, Jiang L, Zhang Y, Sui X. Analytical approaches for assessing protein structure in protein-rich food: A comprehensive review. Food Chem X 2024; 22:101365. [PMID: 38623506 PMCID: PMC11016869 DOI: 10.1016/j.fochx.2024.101365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 03/24/2024] [Accepted: 04/05/2024] [Indexed: 04/17/2024] Open
Abstract
This review focuses on changes in nutrition and functional properties of protein-rich foods, primarily attributed to alterations in protein structures. We provide a comprehensive overview and comparison of commonly used laboratory methods for protein structure identification, aiming to offer readers a convenient understanding of these techniques. The review covers a range of detection technologies employed in food protein analysis and conducts an extensive comparison to identify the most suitable method for various proteins. While these techniques offer distinct advantages for protein structure determination, the inherent complexity of food matrices presents ongoing challenges. Further research is necessary to develop and enhance more robust detection methods to improve accuracy in protein conformation and structure analysis.
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Affiliation(s)
- Tian Lan
- College of Food Science, Northeast Agricultural University, Harbin 150030, China
| | - Yabo Dong
- College of Food Science, Northeast Agricultural University, Harbin 150030, China
| | - Lianzhou Jiang
- College of Food Science, Northeast Agricultural University, Harbin 150030, China
| | - Yan Zhang
- College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China
| | - Xiaonan Sui
- College of Food Science, Northeast Agricultural University, Harbin 150030, China
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Feng RR, Wang M, Zhang W, Gai F. Unnatural Amino Acids for Biological Spectroscopy and Microscopy. Chem Rev 2024; 124:6501-6542. [PMID: 38722769 DOI: 10.1021/acs.chemrev.3c00944] [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: 05/23/2024]
Abstract
Due to advances in methods for site-specific incorporation of unnatural amino acids (UAAs) into proteins, a large number of UAAs with tailored chemical and/or physical properties have been developed and used in a wide array of biological applications. In particular, UAAs with specific spectroscopic characteristics can be used as external reporters to produce additional signals, hence increasing the information content obtainable in protein spectroscopic and/or imaging measurements. In this Review, we summarize the progress in the past two decades in the development of such UAAs and their applications in biological spectroscopy and microscopy, with a focus on UAAs that can be used as site-specific vibrational, fluorescence, electron paramagnetic resonance (EPR), or nuclear magnetic resonance (NMR) probes. Wherever applicable, we also discuss future directions.
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Affiliation(s)
- Ran-Ran Feng
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Manxi Wang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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Das A, Bysack A, Raghuraman H. Cholesterol modulates the structural dynamics of the paddle motif loop of KvAP voltage sensor. Curr Res Struct Biol 2024; 7:100137. [PMID: 38500801 PMCID: PMC10945132 DOI: 10.1016/j.crstbi.2024.100137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/29/2024] [Accepted: 03/03/2024] [Indexed: 03/20/2024] Open
Abstract
KvAP is a prokaryotic Kv channel, which has been widely used as a model system to understand voltage- and lipid-dependent gating mechanisms. In phospholipid membranes, the KvAP-VSD adopts the activated/'Up' conformation, whereas the presence of non-phospholipids in membranes favours the structural transition to resting/'Down' state. The S3b-S4 paddle motif loop of KvAP-VSD is functionally important as this participates in protein-protein interactions and is the target for animal toxins. In this study, we have monitored the modulatory role of cholesterol - the physiologically-relevant non-phospholipid - on the organization and dynamics of the S3b-S4 loop of the isolated KvAP-VSD in membranes by site-directed fluorescence approaches using the environmental sensitivity of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-ethylenediamine (NBD) fluorescence. Our results show that cholesterol alters the dynamic nature (rotational and hydration dynamics) of S3b-S4 loop in a segmental fashion, i.e., the residues 110 to 114 and 115 to 117 behave differently in the presence of cholesterol, which is accompanied by considerable change in conformational heterogeneity. Further, quantitative depth measurements using the parallax quenching method reveal that the sensor loop is located at the shallow interfacial region of cholesterol-containing membranes, suggesting that the sensor loop organization is not directly correlated with S4 helix movement. Our results clearly show that cholesterol-induced changes in bilayer properties may not be the predominant factor for the sensor loop's altered structural dynamics, but can be attributed to the conformational change of the KvAP-VSD in cholesterol-containing membranes. Overall, these results are relevant for gating mechanisms, particularly the lipid-dependent gating, of Kv channels in membranes.
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Affiliation(s)
- Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| | - Arpan Bysack
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| | - H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
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Kyrychenko A, Ladokhin AS. Fluorescent Probes and Quenchers in Studies of Protein Folding and Protein-Lipid Interactions. CHEM REC 2024; 24:e202300232. [PMID: 37695081 PMCID: PMC11113672 DOI: 10.1002/tcr.202300232] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/20/2023] [Indexed: 09/12/2023]
Abstract
Fluorescence spectroscopy provides numerous methodological tools for structural and functional studies of biological macromolecules and their complexes. All fluorescence-based approaches require either existence of an intrinsic probe or an introduction of an extrinsic one. Moreover, studies of complex systems often require an additional introduction of a specific quencher molecule acting in combination with a fluorophore to provide structural or thermodynamic information. Here, we review the fundamentals and summarize the latest progress in applications of different classes of fluorescent probes and their specific quenchers, aimed at studies of protein folding and protein-membrane interactions. Specifically, we discuss various environment-sensitive dyes, FRET probes, probes for short-distance measurements, and several probe-quencher pairs for studies of membrane penetration of proteins and peptides. The goals of this review are: (a) to familiarize the readership with the general concept that complex biological systems often require both a probe and a quencher to decipher mechanistic details of functioning and (b) to provide example of the immediate applications of the described methods.
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Affiliation(s)
- Alexander Kyrychenko
- Institute of Chemistry and School of Chemistry, V. N. Karazin Kharkiv National University, 4 Svobody sq., Kharkiv, 61022, Ukraine
| | - Alexey S Ladokhin
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS, 66160, United States
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Cho SH, Yun Y, Lee DH, Cha JH, Lee SM, Lee J, Suh MH, Lee JH, Oh SH, Park MK, Lee SY. Novel autosomal dominant TMC1 variants linked to hearing loss: insight into protein-lipid interactions. BMC Med Genomics 2023; 16:320. [PMID: 38066485 PMCID: PMC10704677 DOI: 10.1186/s12920-023-01766-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 12/05/2023] [Indexed: 12/18/2023] Open
Abstract
BACKGROUND TMC1, which encodes transmembrane channel-like protein 1, forms the mechanoelectrical transduction (MET) channel in auditory hair cells, necessary for auditory function. TMC1 variants are known to cause autosomal dominant (DFNA36) and autosomal recessive (DFNB7/11) non-syndromic hearing loss, but only a handful of TMC1 variants underlying DFNA36 have been reported, hampering analysis of genotype-phenotype correlations. METHODS In this study, we retrospectively reviewed 338 probands in an in-house database of genetic hearing loss, evaluating the clinical phenotypes and genotypes of novel TMC1 variants associated with DFNA36. To analyze the structural impact of these variants, we generated two structural models of human TMC1, utilizing the Cryo-EM structure of C. elegans TMC1 as a template and AlphaFold protein structure database. Specifically, the lipid bilayer-embedded protein database was used to construct membrane-embedded models of TMC1. We then examined the effect of TMC1 variants on intramolecular interactions and predicted their potential pathogenicity. RESULTS We identified two novel TMC1 variants related to DFNA36 (c.1256T > C:p.Phe419Ser and c.1444T > C:p.Trp482Arg). The affected subjects had bilateral, moderate, late-onset, progressive sensorineural hearing loss with a down-sloping configuration. The Phe419 residue located in the transmembrane domain 4 of TMC1 faces outward towards the channel pore and is in close proximity to the hydrophobic tail of the lipid bilayer. The non-polar-to-polar variant (p.Phe419Ser) alters the hydrophobicity in the membrane, compromising protein-lipid interactions. On the other hand, the Trp482 residue located in the extracellular linker region between transmembrane domains 5 and 6 is anchored to the membrane interfaces via its aromatic rings, mediating several molecular interactions that stabilize the structure of TMC1. This type of aromatic ring-based anchoring is also observed in homologous transmembrane proteins such as OSCA1.2. Conversely, the substitution of Trp with Arg (Trp482Arg) disrupts the cation-π interaction with phospholipids located in the outer leaflet of the phospholipid bilayer, destabilizing protein-lipid interactions. Additionally, Trp482Arg collapses the CH-π interaction between Trp482 and Pro511, possibly reducing the overall stability of the protein. In parallel with the molecular modeling, the two mutants degraded significantly faster compared to the wild-type protein, compromising protein stability. CONCLUSIONS This results expand the genetic spectrum of disease-causing TMC1 variants related to DFNA36 and provide insight into TMC1 transmembrane protein-lipid interactions.
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Affiliation(s)
- Sung Ho Cho
- Seoul National University College of Medicine, Seoul, South Korea
| | - Yejin Yun
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea
| | - Dae Hee Lee
- CTCELLS, Inc, 21, Yuseong-daero, 1205beon-gil, Yuseong-gu, Daejeon, Republic of Korea
| | - Joo Hyun Cha
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea
| | - So Min Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea
| | - Jehyun Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea
| | - Myung Hwan Suh
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea
| | - Jun Ho Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea
| | - Seung-Ha Oh
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea
| | - Moo Kyun Park
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea.
- Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul, South Korea.
| | - Sang-Yeon Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Jongno-Gu, Daehak-Ro, 101, Seoul, South Korea.
- Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul, South Korea.
- Department of Genomic Medicine, Precision Medicine & Rare Disease Center, Seoul, South Korea.
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Meier S, Ridgway ZM, Picciano AL, Caputo GA. Impacts of Hydrophobic Mismatch on Antimicrobial Peptide Efficacy and Bilayer Permeabilization. Antibiotics (Basel) 2023; 12:1624. [PMID: 37998826 PMCID: PMC10669323 DOI: 10.3390/antibiotics12111624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/06/2023] [Accepted: 11/08/2023] [Indexed: 11/25/2023] Open
Abstract
Antimicrobial resistance continues to be a major threat to world health, with the continued emergence of resistant bacterial strains. Antimicrobial peptides have emerged as an attractive option for the development of novel antimicrobial compounds in part due to their ubiquity in nature and the general lack of resistance development to this class of molecules. In this work, we analyzed the antimicrobial peptide C18G and several truncated forms for efficacy and the underlying mechanistic effects of the sequence truncation. The peptides were screened for antimicrobial efficacy against several standard laboratory strains, and further analyzed using fluorescence spectroscopy to evaluate binding to model lipid membranes and bilayer disruption. The results show a clear correlation between the length of the peptide and the antimicrobial efficacy. Furthermore, there is a correlation between peptide length and the hydrophobic thickness of the bilayer, indicating that hydrophobic mismatch is likely a contributing factor to the loss of efficacy in shorter peptides.
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Affiliation(s)
- Steven Meier
- Department of Chemistry & Biochemistry, Rowan University, Glassboro, NJ 08028, USA (A.L.P.)
| | - Zachary M. Ridgway
- Department of Chemistry & Biochemistry, Rowan University, Glassboro, NJ 08028, USA (A.L.P.)
| | - Angela L. Picciano
- Department of Chemistry & Biochemistry, Rowan University, Glassboro, NJ 08028, USA (A.L.P.)
| | - Gregory A. Caputo
- Department of Chemistry & Biochemistry, Rowan University, Glassboro, NJ 08028, USA (A.L.P.)
- Department of Biological & Biomedical Sciences, Rowan University, Glassboro, NJ 08028, USA
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Le N, Chand A, Braun E, Keyes C, Wu Q, Kim K. Interactions between Quantum Dots and G-Actin. Int J Mol Sci 2023; 24:14760. [PMID: 37834208 PMCID: PMC10572542 DOI: 10.3390/ijms241914760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/16/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
Quantum dots (QDs) are a type of nanoparticle with excellent optical properties, suitable for many optical-based biomedical applications. However, the potential of quantum dots to be used in clinical settings is limited by their toxicity. As such, much effort has been invested to examine the mechanism of QDs' toxicity. Yet, the current literature mainly focuses on ROS- and apoptosis-mediated cell death induced by QDs, which overlooks other aspects of QDs' toxicity. Thus, our study aimed to provide another way by which QDs negatively impact cellular processes by investigating the possibility of protein structure and function modification upon direct interaction. Through shotgun proteomics, we identified a number of QD-binding proteins, which are functionally associated with essential cellular processes and components, such as transcription, translation, vesicular trafficking, and the actin cytoskeleton. Among these proteins, we chose to closely examine the interaction between quantum dots and actin, as actin is one of the most abundant proteins in cells and plays crucial roles in cellular processes and structural maintenance. We found that CdSe/ZnS QDs spontaneously bind to G-actin in vitro, causing a static quenching of G-actin's intrinsic fluorescence. Furthermore, we found that this interaction favors the formation of a QD-actin complex with a binding ratio of 1:2.5. Finally, we also found that CdSe/ZnS QDs alter the secondary structure of G-actin, which may affect G-actin's function and properties. Overall, our study provides an in-depth mechanistic examination of the impact of CdSe/ZnS QDs on G-actin, proposing that direct interaction is another aspect of QDs' toxicity.
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Affiliation(s)
- Nhi Le
- Department of Biology, Missouri State University, Springfield, MO 65897, USA; (N.L.); (A.C.); (E.B.)
| | - Abhishu Chand
- Department of Biology, Missouri State University, Springfield, MO 65897, USA; (N.L.); (A.C.); (E.B.)
| | - Emma Braun
- Department of Biology, Missouri State University, Springfield, MO 65897, USA; (N.L.); (A.C.); (E.B.)
| | - Chloe Keyes
- Jordan Valley Innovation Center, Springfield, MO 65806, USA; (C.K.); (Q.W.)
| | - Qihua Wu
- Jordan Valley Innovation Center, Springfield, MO 65806, USA; (C.K.); (Q.W.)
| | - Kyoungtae Kim
- Department of Biology, Missouri State University, Springfield, MO 65897, USA; (N.L.); (A.C.); (E.B.)
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Fouillen A, Bous J, Granier S, Mouillac B, Sounier R. Bringing GPCR Structural Biology to Medical Applications: Insights from Both V2 Vasopressin and Mu-Opioid Receptors. MEMBRANES 2023; 13:606. [PMID: 37367810 PMCID: PMC10303988 DOI: 10.3390/membranes13060606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/05/2023] [Accepted: 06/14/2023] [Indexed: 06/28/2023]
Abstract
G-protein coupled receptors (GPCRs) are versatile signaling proteins that regulate key physiological processes in response to a wide variety of extracellular stimuli. The last decade has seen a revolution in the structural biology of clinically important GPCRs. Indeed, the improvement in molecular and biochemical methods to study GPCRs and their transducer complexes, together with advances in cryo-electron microscopy, NMR development, and progress in molecular dynamic simulations, have led to a better understanding of their regulation by ligands of different efficacy and bias. This has also renewed a great interest in GPCR drug discovery, such as finding biased ligands that can either promote or not promote specific regulations. In this review, we focus on two therapeutically relevant GPCR targets, the V2 vasopressin receptor (V2R) and the mu-opioid receptor (µOR), to shed light on the recent structural biology studies and show the impact of this integrative approach on the determination of new potential clinical effective compounds.
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Affiliation(s)
- Aurélien Fouillen
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34000 Montpellier, France; (A.F.); (S.G.); (B.M.)
- Centre de Biochimie Structurale (CBS), Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France
| | - Julien Bous
- Section of Receptor Biology & Signaling, Department of Physiology & Pharmacology, Karolinska Institutet, 17165 Stockholm, Sweden;
| | - Sébastien Granier
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34000 Montpellier, France; (A.F.); (S.G.); (B.M.)
| | - Bernard Mouillac
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34000 Montpellier, France; (A.F.); (S.G.); (B.M.)
| | - Remy Sounier
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34000 Montpellier, France; (A.F.); (S.G.); (B.M.)
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Kegulian NC, Langen R, Moradian-Oldak J. The Dynamic Interactions of a Multitargeting Domain in Ameloblastin Protein with Amelogenin and Membrane. Int J Mol Sci 2023; 24:3484. [PMID: 36834897 PMCID: PMC9966149 DOI: 10.3390/ijms24043484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/28/2023] [Accepted: 02/06/2023] [Indexed: 02/12/2023] Open
Abstract
The enamel matrix protein Ameloblastin (Ambn) has critical physiological functions, including regulation of mineral formation, cell differentiation, and cell-matrix adhesion. We investigated localized structural changes in Ambn during its interactions with its targets. We performed biophysical assays and used liposomes as a cell membrane model. The xAB2N and AB2 peptides were rationally designed to encompass regions of Ambn that contained self-assembly and helix-containing membrane-binding motifs. Electron paramagnetic resonance (EPR) on spin-labeled peptides showed localized structural gains in the presence of liposomes, amelogenin (Amel), and Ambn. Vesicle clearance and leakage assays indicated that peptide-membrane interactions were independent from peptide self-association. Tryptophan fluorescence and EPR showed competition between Ambn-Amel and Ambn-membrane interactions. We demonstrate localized structural changes in Ambn upon interaction with different targets via a multitargeting domain, spanning residues 57 to 90 of mouse Ambn. Structural changes of Ambn following its interaction with different targets have relevant implications for the multifunctionality of Ambn in enamel formation.
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Affiliation(s)
- Natalie C. Kegulian
- Center for Craniofacial Molecular Biology, Department of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
| | - Ralf Langen
- Department of Neuroscience and Physiology, Department of Biochemistry and Molecular Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Department of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
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13
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dos Santos Rodrigues FH, Delgado GG, Santana da Costa T, Tasic L. Applications of fluorescence spectroscopy in protein conformational changes and intermolecular contacts. BBA ADVANCES 2023; 3:100091. [PMID: 37207090 PMCID: PMC10189374 DOI: 10.1016/j.bbadva.2023.100091] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023] Open
Abstract
Emission fluorescence is one of the most versatile and powerful biophysical techniques used in several scientific subjects. It is extensively applied in the studies of proteins, their conformations, and intermolecular contacts, such as in protein-ligand and protein-protein interactions, allowing qualitative, quantitative, and structural data elucidation. This review, aimed to outline some of the most widely used fluorescence techniques in this area, illustrate their applications and display a few examples. At first, the data on the intrinsic fluorescence of proteins is disclosed, mainly on the tryptophan side chain. Predominantly, research to study protein conformational changes, protein interactions, and changes in intensities and shifts of the fluorescence emission maximums were discussed. Fluorescence anisotropy or fluorescence polarization is a measurement of the changing orientation of a molecule in space, concerning the time between the absorption and emission events. Absorption and emission indicate the spatial alignment of the molecule's dipoles relative to the electric vector of the electromagnetic wave of excitation and emitted light, respectively. In other words, if the fluorophore population is excited with vertically polarized light, the emitted light will retain some polarization based on how fast it rotates in solution. Therefore, fluorescence anisotropy can be successfully used in protein-protein interaction investigations. Then, green fluorescent proteins (GFPs), photo-transformable fluorescent proteins (FPs) such as photoswitchable and photoconvertible FPs, and those with Large Stokes Shift (LSS) are disclosed in more detail. FPs are potent tools for the study of biological systems. Their versatility and wide range of colours and properties allow many applications. Finally, the application of fluorescence in life sciences is exposed, especially the application of FPs in fluorescence microscopy techniques with super-resolution that enables precise in vivo photolabeling to monitor the movement and interactions of target proteins.
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Affiliation(s)
| | - Gonzalo Garcia Delgado
- Chemical Biology Laboratory, Institute of Chemistry, Organic Chemistry Department, University of Campinas, P. O. Box 6154, Campinas 13083-970, SP, Brazil
| | - Thyerre Santana da Costa
- Chemical Biology Laboratory, Institute of Chemistry, Organic Chemistry Department, University of Campinas, P. O. Box 6154, Campinas 13083-970, SP, Brazil
| | - Ljubica Tasic
- Chemical Biology Laboratory, Institute of Chemistry, Organic Chemistry Department, University of Campinas, P. O. Box 6154, Campinas 13083-970, SP, Brazil
- Corresponding author: Ljubica Tasic: IQ, UNICAMP, Rua Josué de Castro sn, 13083-970 Campinas, SP, Brazil
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14
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Raghuraman H, Böckmann A. Editorial: Structural dynamics of membrane proteins, Volume II. Front Mol Biosci 2022; 9:1037083. [PMID: 36310593 PMCID: PMC9608756 DOI: 10.3389/fmolb.2022.1037083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 09/27/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
- *Correspondence: H. Raghuraman, ; Anja Böckmann,
| | - Anja Böckmann
- Microbiologie Moléculaire et Biochimie Structurale (MMSB), UMR5086 CNRS, Lyon University, Lyon, France
- *Correspondence: H. Raghuraman, ; Anja Böckmann,
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15
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Povilaitis SC, Fathizadeh A, Kogan M, Elber R, Webb LJ. Design of Peptides for Membrane Insertion: The Critical Role of Charge Separation. J Phys Chem B 2022; 126:6454-6463. [PMID: 35997537 PMCID: PMC9541189 DOI: 10.1021/acs.jpcb.2c04615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A physical understanding of membrane permeation and translocation by small, positively charged molecules can illuminate cell penetrating peptide mechanisms of entry and inform drug design. We have previously investigated the permeation of the doubly charged peptide WKW and proposed a defect-assisted permeation mechanism where a small molecule with +2 charge can achieve a metastable state spanning the bilayer by forming a membrane defect with charges stabilized by phospholipid phosphate groups. Here, we investigate the membrane permeation of two doubly charged peptides, WWK and WWWK, with charges separated by different lengths. Through complementary experiments and molecular dynamics simulations, we show that membrane permeation was an order of magnitude more favorable when charges were separated by an ∼2-3 Å greater distance on WWWK compared to WWK. These results agree with the previously proposed defect-assisted permeation mechanism, where a greater distance between positive charges would require a less extreme membrane defect to stabilize the membrane-spanning metastable state. We discuss the implications of these results in understanding the membrane permeation of cell-penetrating peptides and other small, positively charged membrane permeants.
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Affiliation(s)
- Sydney C. Povilaitis
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, United States
| | - Arman Fathizadeh
- Oden Institute for Computational Engineering and Science, University of Texas at Austin, Austin, Texas 78712, United States
| | - Molly Kogan
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, United States
| | - Ron Elber
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, United States
- Oden Institute for Computational Engineering and Science, University of Texas at Austin, Austin, Texas 78712, United States
| | - Lauren J. Webb
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, United States
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16
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Brahma R, Raghuraman H. Cost-effective Purification of Membrane Proteins using a Dual-detergent Strategy. Curr Protoc 2022; 2:e452. [PMID: 35714356 PMCID: PMC7614515 DOI: 10.1002/cpz1.452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Understanding the mechanisms of membrane protein function is critical for biomedical research and drug discovery as membrane proteins constitute ∼30% of the proteins encoded by the genomes of both lower and higher organisms and are targets for two-thirds of approved drugs worldwide. Significant progress has been made in engineering host expression systems for large-scale production of membrane proteins and in determining their three-dimensional high-resolution structures. Despite these efforts, the study of membrane proteins at the atomic level is challenging due to poor expression and extraction, low yields of functional protein, and the complexity and heterogeneity of source membranes. Structural and spectroscopic studies of any membrane protein require that the protein be extracted from its native membranes into a membrane-mimetic stable environment, which is often achieved by the use of detergents. Unfortunately, there is no magic detergent that can extract all membrane proteins and successful extraction often requires a thorough screen of detergents. Furthermore, membrane protein purification in general and the detergents used are very expensive, which puts a financial constraint on sophisticated membrane protein studies. To overcome this hurdle, a dual-detergent strategy has recently been developed and successfully applied to purify various classes of pure, stable, and functionally relevant membrane proteins in a cost-effective manner. This strategy uses an inexpensive detergent for solubilization of the desired protein from membranes and a second detergent during protein purification. In the Basic Protocol, we describe the dual-detergent strategy to significantly reduce the overall purification cost of a bacterial membrane protein using the magnesium ion channel MgtE as an example. Support Protocols are also provided for selecting a suitable E. coli strain for protein expression and the optimal detergent(s) for membrane protein solubilization. © 2022 Wiley Periodicals LLC. Basic Protocol: Expression, membrane solubilization, and cost-effective purification of MgtE Support Protocol 1: Selecting a suitable E. coli strain for optimal protein expression Support Protocol 2: Identification of suitable detergents for membrane protein solubilization.
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Affiliation(s)
- Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Bidhannagar, Kolkata, India.,Homi Bhabha National Institute, Anushaktinagar, Mumbai, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Bidhannagar, Kolkata, India.,Homi Bhabha National Institute, Anushaktinagar, Mumbai, India
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17
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Brahma R, Das A, Raghuraman H. Site-directed fluorescence approaches to monitor the structural dynamics of proteins using intrinsic Trp and labeled with extrinsic fluorophores. STAR Protoc 2022; 3:101200. [PMID: 35252885 PMCID: PMC8889417 DOI: 10.1016/j.xpro.2022.101200] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Comprehensive understanding of a protein's function depends on having reliable, sophisticated tools to study protein structural dynamics in physiologically-relevant conditions. Here, we present an effective, robust step-by-step protocol to monitor the structural dynamics (including hydration dynamics) of a protein utilizing various site-directed fluorescence (SDFL) approaches. This protocol should be widely applicable for studying soluble proteins, intrinsically-disordered proteins, and membrane proteins. For complete details on the use and execution of this protocol, please refer to Das et al. (2020), Das and Raghuraman (2021), and Chatterjee et al. (2021).
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Affiliation(s)
- Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata 700 064, India
| | - Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata 700 064, India
| | - H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata 700 064, India
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18
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Brahma R, Raghuraman H. Measuring Membrane Penetration Depths and Conformational Changes in Membrane Peptides and Proteins. J Membr Biol 2022; 255:469-483. [PMID: 35274157 DOI: 10.1007/s00232-022-00224-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 02/23/2022] [Indexed: 10/18/2022]
Abstract
The structural organization and dynamic nature of the biomembrane components are important determinants for numerous cellular functions. Particularly, membrane proteins are critically important for various physiological functions and are important drug targets. The mechanistic insights on the complex functionality of membrane lipids and proteins can be elucidated by understanding the interplay between structure and dynamics. In this regard, membrane penetration depth represents an important parameter to obtain the precise depth of membrane-embedded molecules that often define the conformation and topology of membrane probes and proteins. In this review, we discuss about the widely used fluorescence quenching-based methods (parallax method, distribution analysis, and dual-quencher analysis) to accurately determine the membrane penetration depths of fluorescent probes that are either membrane-embedded or attached to lipids and proteins. Further, we also discuss a relatively novel fluorescence quenching method that utilizes tryptophan residue as the quencher, namely the tryptophan-induced quenching, which is sensitive to monitor small-scale conformational changes (short distances of < 15 Å) and useful in mapping distances in proteins. We have provided numerous examples for the benefit of readers to appreciate the importance and applicability of these simple yet powerful methods to study membrane proteins.
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Affiliation(s)
- Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF, Bidhannagar, Kolkata, 700 064, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF, Bidhannagar, Kolkata, 700 064, India.
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19
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Das A, Bysack A, Raghuraman H. Effectiveness of dual-detergent strategy using Triton X-100 in membrane protein purification. Biochem Biophys Res Commun 2021; 578:122-128. [PMID: 34560581 DOI: 10.1016/j.bbrc.2021.09.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 09/16/2021] [Indexed: 11/27/2022]
Abstract
Membrane solubilization by detergents is a critical step for successful membrane protein purification. Alkyl maltoside detergents such as DDM and DM are very expensive and are commonly used to produce most of the high-quality proteins in stable and functional form. Recently, dual-detergent strategy using inexpensive detergents for membrane solubilization step has been shown to be highly effective in purifying different classes of membrane proteins in a cost-effective manner. In this work, we have monitored the effectiveness of 'dual-detergent strategy' towards successful purification of the isolated voltage sensing domain (VSD) of KvAP and the inward rectifying K+ channel, KirBac1.1. We demonstrate that the inexpensive detergent Triton X-100 extracts the activated conformation of the KvAP-VSD well without compromising the structural integrity of the sensor, and also retains its proper structural dynamics. Importantly, the cost associated with solubilizing the KvAP sensor can be reduced by ∼2000 fold. To the best of our knowledge, our results constitute the first report characterizing the purification of KvAP voltage sensor using an inexpensive detergent. However, the dual-detergent strategy using Triton X-100 for membrane solubilization is not effective for the purification of inward rectifying K+ channel, KirBac1.1 even in presence of high salt concentration during solubilization. We propose that the dual-detergent strategy will be useful for extracting stable and functional proteins that are both DDM- and DM-extractable, but will be ineffective if the protein is only DM-extractable. The relevance of the effectiveness of dual-detergent strategy with respect to the hydrophobic thickness of proteins is discussed.
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Affiliation(s)
- Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, 700 064, India
| | - Arpan Bysack
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, 700 064, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, 700 064, India.
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20
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Majeed S, Ahmad AB, Sehar U, Georgieva ER. Lipid Membrane Mimetics in Functional and Structural Studies of Integral Membrane Proteins. MEMBRANES 2021; 11:685. [PMID: 34564502 PMCID: PMC8470526 DOI: 10.3390/membranes11090685] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/18/2021] [Accepted: 08/30/2021] [Indexed: 12/12/2022]
Abstract
Integral membrane proteins (IMPs) fulfill important physiological functions by providing cell-environment, cell-cell and virus-host communication; nutrients intake; export of toxic compounds out of cells; and more. However, some IMPs have obliterated functions due to polypeptide mutations, modifications in membrane properties and/or other environmental factors-resulting in damaged binding to ligands and the adoption of non-physiological conformations that prevent the protein from returning to its physiological state. Thus, elucidating IMPs' mechanisms of function and malfunction at the molecular level is important for enhancing our understanding of cell and organism physiology. This understanding also helps pharmaceutical developments for restoring or inhibiting protein activity. To this end, in vitro studies provide invaluable information about IMPs' structure and the relation between structural dynamics and function. Typically, these studies are conducted on transferred from native membranes to membrane-mimicking nano-platforms (membrane mimetics) purified IMPs. Here, we review the most widely used membrane mimetics in structural and functional studies of IMPs. These membrane mimetics are detergents, liposomes, bicelles, nanodiscs/Lipodisqs, amphipols, and lipidic cubic phases. We also discuss the protocols for IMPs reconstitution in membrane mimetics as well as the applicability of these membrane mimetic-IMP complexes in studies via a variety of biochemical, biophysical, and structural biology techniques.
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Affiliation(s)
- Saman Majeed
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Akram Bani Ahmad
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Ujala Sehar
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Elka R Georgieva
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Science Center, Lubbock, TX 79409, USA
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21
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Hilger D. The role of structural dynamics in GPCR‐mediated signaling. FEBS J 2021; 288:2461-2489. [DOI: 10.1111/febs.15841] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/19/2021] [Accepted: 03/24/2021] [Indexed: 12/18/2022]
Affiliation(s)
- Daniel Hilger
- Department of Pharmaceutical Chemistry Philipps‐University Marburg Germany
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22
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Das A, Raghuraman H. Conformational heterogeneity of the voltage sensor loop of KvAP in micelles and membranes: A fluorescence approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183568. [PMID: 33529577 DOI: 10.1016/j.bbamem.2021.183568] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/06/2021] [Accepted: 01/27/2021] [Indexed: 12/14/2022]
Abstract
KvAP is a tetrameric voltage-gated potassium channel that is composed of a pore domain and a voltage-sensing domain (VSD). The VSD is crucial for sensing transmembrane potential and gating. At 0 mV, the VSD adopts an activated conformation in both n-octylglucoside (OG) micelles and phospholipid membranes. Importantly, gating-modifier toxins that bind at S3b-S4 loop of KvAP-VSD exhibit pronounced differences in binding affinity in these membrane-mimetic systems. However, the conformational heterogeneity of this functionally-important sensor loop in membrane mimetics is poorly understood, and is the focus of this work. In this paper, we establish, using intrinsic fluorescence of the uniquely positioned W70 in KvAP-VSD and environment-sensitive NBD (7-nitrobenz-2-oxa-1,3-diazol-4-yl-ethylenediamine) fluorescence of the labelled S3b-S4 loop, that the surface charge of the membrane does not significantly affect the topology and structural dynamics of the sensor loop in membranes. Importantly, the dynamic variability of the sensor loop is preserved in both zwitterionic (POPC) and anionic (POPC/POPG) membranes. Further, the lifetime distribution analysis for the NBD-labelled residues by maximum entropy method (MEM) demonstrates that, in contrast to micelles, the membrane environment not only reduces the relative discrete population of sensor loop conformations, but also broadens the lifetime distribution peaks. Overall, our results strongly suggest that the conformational heterogeneity of the sensor loop is significantly altered in membranes and this correlates well with its environmental heterogeneity. This constitutes the first report demonstrating that MEM-lifetime distribution could be a powerful tool to distinguish changes in conformational heterogeneity in potassium channels with similar architecture and topology.
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Affiliation(s)
- Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India.
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23
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Novel insights in linking solvent relaxation dynamics and protein conformations utilizing red edge excitation shift approach. Emerg Top Life Sci 2021; 5:89-101. [PMID: 33416893 DOI: 10.1042/etls20200256] [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: 10/21/2020] [Revised: 12/14/2020] [Accepted: 12/18/2020] [Indexed: 01/01/2023]
Abstract
Protein hydration dynamics plays an important role in many physiological processes since protein fluctuations, slow solvation, and the dynamics of hydrating water are all intrinsically related. Red edge excitation shift (REES) is a unique and powerful wavelength-selective (i.e. excitation-energy dependent) fluorescence approach that can be used to directly monitor the environment-induced restriction and dynamics around a polar fluorophore in a complex biological system. This review is mainly focused on recent applications of REES and a novel analysis of REES data to monitor the structural dynamics, functionally relevant conformational transitions and to unmask the structural ensembles in proteins. In addition, the novel utility of REES in imaging protein aggregates in a cellular context is discussed. We believe that the enormous potential of REES approach showcased in this review will engage more researchers, particularly from life sciences.
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24
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Chatterjee S, Brahma R, Raghuraman H. Gating-related Structural Dynamics of the MgtE Magnesium Channel in Membrane-Mimetics Utilizing Site-Directed Tryptophan Fluorescence. J Mol Biol 2020; 433:166691. [PMID: 33203509 DOI: 10.1016/j.jmb.2020.10.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/17/2020] [Accepted: 10/19/2020] [Indexed: 12/25/2022]
Abstract
Magnesium is the most abundant divalent cation present in the cell, and an abnormal Mg2+ homeostasis is associated with several diseases in humans. However, among ion channels, the mechanisms of intracellular regulation and transport of Mg2+ are poorly understood. MgtE is a homodimeric Mg2+-selective channel and is negatively regulated by high intracellular Mg2+ concentration where the cytoplasmic domain of MgtE acts as a Mg2+ sensor. Most of the previous biophysical studies on MgtE have been carried out in detergent micelles and the information regarding gating-related structural dynamics of MgtE in physiologically-relevant membrane environment is scarce. In this work, we monitored the changes in gating-related structural dynamics, hydration dynamics and conformational heterogeneity of MgtE in micelles and membranes using the intrinsic site-directed Trp fluorescence. For this purpose, we have engineered six single-Trp mutants in the functional Trp-less background of MgtE to obtain site-specific information on the gating-related structural dynamics of MgtE in membrane-mimetic systems. Our results indicate that Mg2+-induced gating might involve the possibility of a 'conformational wave' from the cytosolic N-domain to transmembrane domain of MgtE. Although MgtE is responsive to Mg2+-induced gating in both micelles and membranes, the organization and dynamics of MgtE is substantially altered in physiologically important phospholipid membranes compared to micelles. This is accompanied by significant changes in hydration dynamics and conformational heterogeneity. Overall, our results highlight the importance of lipid-protein interactions and are relevant for understanding gating mechanism of magnesium channels in general, and MgtE in particular.
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Affiliation(s)
- Satyaki Chatterjee
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India.
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25
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Probing conformational transitions of PIN1 from L. major during chemical and thermal denaturation. Int J Biol Macromol 2020; 154:904-915. [PMID: 32209371 DOI: 10.1016/j.ijbiomac.2020.03.166] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/13/2020] [Accepted: 03/13/2020] [Indexed: 01/03/2023]
Abstract
PIN1 proteins are a class of peptidyl prolyl cis-trans isomerases (PPIases), which have been implicated in numerous cellular functions like cell cycle progression, transcriptional control, signal transduction, promotion of oncogenesis and host-parasite interactions. In this work, the unfolding mechanism of a single domain PIN1 from Leishmania major (LmPIN1) has been characterized during thermal and denaturant-induced unfolding by differential scanning calorimetry (DSC), fluorescence and circular dichroism. Further, MD simulations have been performed to structurally probe the possible stages of its unfolding process. Both the fluorescence and CD data confirm classical two-state unfolding transitions for urea and GdnHCl. The thermal unfolding of LmPIN1, characterized by DSC, could optimally be fitted to a non two-state transition curve exhibiting two Tm's (53 °C and 57 °C) suggesting the possibility of an intermediate. Thermal unfolding of the modeled LmPIN1 by MD simulation shows that the unfolding process is initiated by increased fluctuations (dynamics) spanning residues 70-80, followed by perturbations in the sheet system and disjuncture of helix-sheet packing. Importantly, simulation and fluorescence quenching studies clearly suggest the possibility of the presence of residual structures of LmPIN1 even after complete denaturation.
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26
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Richardson RJ, Fink JK, Glynn P, Hufnagel RB, Makhaeva GF, Wijeyesakere SJ. Neuropathy target esterase (NTE/PNPLA6) and organophosphorus compound-induced delayed neurotoxicity (OPIDN). ADVANCES IN NEUROTOXICOLOGY 2020; 4:1-78. [PMID: 32518884 PMCID: PMC7271139 DOI: 10.1016/bs.ant.2020.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Systemic inhibition of neuropathy target esterase (NTE) with certain organophosphorus (OP) compounds produces OP compound-induced delayed neurotoxicity (OPIDN), a distal degeneration of axons in the central nervous system (CNS) and peripheral nervous system (PNS), thereby providing a powerful model for studying a spectrum of neurodegenerative diseases. Axonopathies are important medical entities in their own right, but in addition, illnesses once considered primary neuronopathies are now thought to begin with axonal degeneration. These disorders include Alzheimer's disease, Parkinson's disease, and motor neuron diseases such as amyotrophic lateral sclerosis (ALS). Moreover, conditional knockout of NTE in the mouse CNS produces vacuolation and other degenerative changes in large neurons in the hippocampus, thalamus, and cerebellum, along with degeneration and swelling of axons in ascending and descending spinal cord tracts. In humans, NTE mutations cause a variety of neurodegenerative conditions resulting in a range of deficits including spastic paraplegia and blindness. Mutations in the Drosophila NTE orthologue SwissCheese (SWS) produce neurodegeneration characterized by vacuolization that can be partially rescued by expression of wild-type human NTE, suggesting a potential therapeutic approach for certain human neurological disorders. This chapter defines NTE and OPIDN, presents an overview of OP compounds, provides a rationale for NTE research, and traces the history of discovery of NTE and its relationship to OPIDN. It then briefly describes subsequent studies of NTE, including practical applications of the assay; aspects of its domain structure, subcellular localization, and tissue expression; abnormalities associated with NTE mutations, knockdown, and conventional or conditional knockout; and hypothetical models to help guide future research on elucidating the role of NTE in OPIDN.
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Affiliation(s)
- Rudy J. Richardson
- Molecular Simulations Laboratory, Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, United States,Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States,Center for Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, United States,Michigan Institute for Computational Discovery and Engineering, University of Michigan, Ann Arbor, MI, United States,Corresponding author:
| | - John K. Fink
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States,Ann Arbor Veterans Affairs Medical Center, Ann Arbor, MI, United States
| | - Paul Glynn
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Robert B. Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Galina F. Makhaeva
- Institute of Physiologically Active Compounds Russian Academy of Sciences, Chernogolovka, Russia
| | - Sanjeeva J. Wijeyesakere
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States
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Das A, Chatterjee S, Raghuraman H. Structural Dynamics of the Paddle Motif Loop in the Activated Conformation of KvAP Voltage Sensor. Biophys J 2019; 118:873-884. [PMID: 31547975 DOI: 10.1016/j.bpj.2019.08.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/31/2019] [Accepted: 08/06/2019] [Indexed: 02/07/2023] Open
Abstract
Voltage-dependent potassium (Kv) channels play a fundamental role in neuronal and cardiac excitability and are potential therapeutic targets. They assemble as tetramers with a centrally located pore domain surrounded by a voltage-sensing domain (VSD), which is critical for sensing transmembrane potential and subsequent gating. Although the sensor is supposed to be in "Up" conformation in both n-octylglucoside (OG) micelles and phospholipid membranes in the absence of membrane potential, toxins that bind VSD and modulate the gating behavior of Kv channels exhibit dramatic affinity differences in these membrane-mimetic systems. In this study, we have monitored the structural dynamics of the S3b-S4 loop of the paddle motif in activated conformation of KvAP-VSD by site-directed fluorescence approaches, using the environment-sensitive fluorescent probe 7-nitrobenz-2-oxa-1,3-diazol-4-yl-ethylenediamine (NBD). Emission maximum of NBD-labeled loop region of KvAP-VSD (residues 110-117) suggests a significant change in the polarity of local environment in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) membranes compared to OG micelles. This indicates that S3b-S4 loop residues might be partitioning to membrane interface, which is supported by an overall increased mean fluorescence lifetimes and significantly reduced water accessibility in membranes. Further, the magnitude of red edge excitation shift (REES) supports the presence of restricted/bound water molecules in the loop region of the VSD in micelles and membranes. Quantitative analysis of REES data using Gaussian probability distribution function clearly indicates that the sensor loop has fewer discrete equilibrium conformational states when reconstituted in membranes. Interestingly, this reduced molecular heterogeneity is consistent with the site-specific NBD polarization results, which suggest that the membrane environment offers a relaxed/dynamic organization for most of the S3b-S4 loop residues of the sensor. Overall, our results are relevant for understanding toxin-VSD interaction and gating mechanisms of Kv channels in membranes.
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Affiliation(s)
- Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - Satyaki Chatterjee
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, 1/AF Bidhannagar, Kolkata, India.
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