1
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Iwamoto M, Morito M, Oiki S, Nishitani Y, Yamamoto D, Matsumori N. Cardiolipin binding enhances KcsA channel gating via both its specific and dianion-monoanion interchangeable sites. iScience 2023; 26:108471. [PMID: 38077151 PMCID: PMC10709135 DOI: 10.1016/j.isci.2023.108471] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 10/29/2023] [Accepted: 11/13/2023] [Indexed: 01/17/2024] Open
Abstract
KcsA is a potassium channel with a plethora of structural and functional information, but its activity in the KcsA-producing actinomycete membranes remains elusive. To determine lipid species involved in channel-modulation, a surface plasmon resonance (SPR)-based methodology, characterized by immobilization of membrane proteins under a membrane environment, was applied. Dianionic cardiolipin (CL) showed extremely higher affinity for KcsA than monoanionic lipids. The SPR experiments further demonstrated that CL bound not only to the N-terminal M0 helix, a lipid-sensor domain, but to the M0 helix-deleted mutant. In contrast, monoanionic lipids interacted primarily with the M0 helix. This indicates the presence of an alternative CL-binding site, plausibly in the transmembrane domain. Single-channel recordings demonstrated that CL enhanced channel opening in an M0-independent manner. Taken together, the action of monoanionic lipids is exclusively mediated by the M0 helix, while CL binds both the M0 helix and its specific site, further enhancing the channel activity.
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Affiliation(s)
- Masayuki Iwamoto
- Department of Molecular Neuroscience, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan
| | - Masayuki Morito
- Department of Chemistry, Graduate School of Science, Kyushu University, Fukuoka 819-0395 Japan
| | - Shigetoshi Oiki
- Biomedial Imaging Research Center, University of Fukui, Fukui 910-1193, Japan
| | - Yudai Nishitani
- Department of Applied Physics, Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan
| | - Daisuke Yamamoto
- Department of Applied Physics, Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan
| | - Nobuaki Matsumori
- Department of Chemistry, Graduate School of Science, Kyushu University, Fukuoka 819-0395 Japan
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2
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Stępień P, Świątek S, Robles MYY, Markiewicz-Mizera J, Balakrishnan D, Inaba-Inoue S, De Vries AH, Beis K, Marrink SJ, Heddle JG. CRAFTing Delivery of Membrane Proteins into Protocells using Nanodiscs. ACS APPLIED MATERIALS & INTERFACES 2023; 15. [PMID: 38015973 PMCID: PMC10726305 DOI: 10.1021/acsami.3c11894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 11/07/2023] [Accepted: 11/07/2023] [Indexed: 11/30/2023]
Abstract
For the successful generative engineering of functional artificial cells, a convenient and controllable means of delivering membrane proteins into membrane lipid bilayers is necessary. Here we report a delivery system that achieves this by employing membrane protein-carrying nanodiscs and the calcium-dependent fusion of phosphatidylserine lipid membranes. We show that lipid nanodiscs can fuse a transported lipid bilayer with the lipid bilayers of small unilamellar vesicles (SUVs) or giant unilamellar vesicles (GUVs) while avoiding recipient vesicles aggregation. This is triggered by a simple, transient increase in calcium concentration, which results in efficient and rapid fusion in a one-pot reaction. Furthermore, nanodiscs can be loaded with membrane proteins that can be delivered into target SUV or GUV membranes in a detergent-independent fashion while retaining their functionality. Nanodiscs have a proven ability to carry a wide range of membrane proteins, control their oligomeric state, and are highly adaptable. Given this, our approach may be the basis for the development of useful tools that will allow bespoke delivery of membrane proteins to protocells, equipping them with the cell-like ability to exchange material across outer/subcellular membranes.
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Affiliation(s)
- Piotr Stępień
- Malopolska
Centre of Biotechnology, Jagiellonian University, Krakow 30-387, Poland
| | - Sylwia Świątek
- Malopolska
Centre of Biotechnology, Jagiellonian University, Krakow 30-387, Poland
| | | | | | - Dhanasekaran Balakrishnan
- Malopolska
Centre of Biotechnology, Jagiellonian University, Krakow 30-387, Poland
- Postgraduate
School of Molecular Medicine, Żwirki i Wigury 61, Warsaw 02-091, Poland
| | - Satomi Inaba-Inoue
- Department
of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, U.K.
- Rutherford
Appleton Laboratory, Research Complex at
Harwell, Didcot, Oxfordshire OX11 0FA, U.K.
| | - Alex H. De Vries
- Groningen
Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Konstantinos Beis
- Department
of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, U.K.
- Rutherford
Appleton Laboratory, Research Complex at
Harwell, Didcot, Oxfordshire OX11 0FA, U.K.
| | - Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Jonathan G. Heddle
- Malopolska
Centre of Biotechnology, Jagiellonian University, Krakow 30-387, Poland
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3
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Pukyšová V, Sans Sánchez A, Rudolf J, Nodzyński T, Zwiewka M. Arabidopsis flippase ALA3 is required for adjustment of early subcellular trafficking in plant response to osmotic stress. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4959-4977. [PMID: 37353222 PMCID: PMC10498020 DOI: 10.1093/jxb/erad234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 06/23/2023] [Indexed: 06/25/2023]
Abstract
To compensate for their sessile lifestyle, plants developed several responses to exogenous changes. One of the previously investigated and not yet fully understood adaptations occurs at the level of early subcellular trafficking, which needs to be rapidly adjusted to maintain cellular homeostasis and membrane integrity under osmotic stress conditions. To form a vesicle, the membrane needs to be deformed, which is ensured by multiple factors, including the activity of specific membrane proteins, such as flippases from the family of P4-ATPases. The membrane pumps actively translocate phospholipids from the exoplasmic/luminal to the cytoplasmic membrane leaflet to generate curvature, which might be coupled with recruitment of proteins involved in vesicle formation at specific sites of the donor membrane. We show that lack of the AMINOPHOSPHOLIPID ATPASE3 (ALA3) flippase activity caused defects at the plasma membrane and trans-Golgi network, resulting in altered endocytosis and secretion, processes relying on vesicle formation and movement. The mentioned cellular defects were translated into decreased intracellular trafficking flexibility failing to adjust the root growth on osmotic stress-eliciting media. In conclusion, we show that ALA3 cooperates with ARF-GEF BIG5/BEN1 and ARF1A1C/BEX1 in a similar regulatory pathway to vesicle formation, and together they are important for plant adaptation to osmotic stress.
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Affiliation(s)
- Vendula Pukyšová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University (MU), Kamenice 5, CZ 625 00, Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Adrià Sans Sánchez
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University (MU), Kamenice 5, CZ 625 00, Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Jiří Rudolf
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University (MU), Kamenice 5, CZ 625 00, Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Tomasz Nodzyński
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University (MU), Kamenice 5, CZ 625 00, Brno, Czech Republic
| | - Marta Zwiewka
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University (MU), Kamenice 5, CZ 625 00, Brno, Czech Republic
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4
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Miszta P, Pasznik P, Niewieczerzał S, Młynarczyk K, Filipek S. COGRIMEN: Coarse-Grained Method for Modeling of Membrane Proteins in Implicit Environments. J Chem Theory Comput 2022; 18:5145-5156. [PMID: 35998323 PMCID: PMC9476660 DOI: 10.1021/acs.jctc.2c00140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The presented methodology is based on coarse-grained
representation
of biomolecules in implicit environments and is designed for the molecular
dynamics simulations of membrane proteins and their complexes. The
membrane proteins are not only found in the cell membrane but also
in all membranous compartments of the cell: Golgi apparatus, mitochondria,
endosomes and lysosomes, and they usually form large complexes. To
investigate such systems the methodology is proposed based on two
independent approaches combining the coarse-grained MARTINI model
for proteins and the effective energy function to mimic the water/membrane
environments. The latter is based on the implicit environment developed
for all-atom simulations in the IMM1 method. The force field solvation
parameters for COGRIMEN were initially calculated from IMM1 all-atom
parameters and then optimized using Genetic Algorithms. The new methodology
was tested on membrane proteins, their complexes and oligomers. COGRIMEN
method is implemented as a patch for NAMD program and can be useful
for fast and brief studies of large membrane protein complexes.
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Affiliation(s)
- Przemysław Miszta
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw 02-093, Poland
| | - Paweł Pasznik
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw 02-093, Poland
| | - Szymon Niewieczerzał
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw 02-093, Poland
| | - Krzysztof Młynarczyk
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw 02-093, Poland
| | - Sławomir Filipek
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw 02-093, Poland
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5
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Qin S, Hicks A, Dey S, Prasad R, Zhou HX. ReSMAP: Web Server for Predicting Residue-Specific Membrane-Association Propensities of Intrinsically Disordered Proteins. MEMBRANES 2022; 12:773. [PMID: 36005688 PMCID: PMC9416665 DOI: 10.3390/membranes12080773] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/02/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
The functional processes of many proteins involve the association of their intrinsically disordered regions (IDRs) with acidic membranes. We have identified the membrane-association characteristics of IDRs using extensive molecular dynamics (MD) simulations and validated them with NMR spectroscopy. These studies have led to not only deep insight into functional mechanisms of IDRs but also to intimate knowledge regarding the sequence determinants of membrane-association propensities. Here we turned this knowledge into a web server called ReSMAP, for predicting the residue-specific membrane-association propensities from IDR sequences. The membrane-association propensities are calculated from a sequence-based partition function, trained on the MD simulation results of seven IDRs. Robustness of the prediction is demonstrated by leaving one IDR out of the training set. We anticipate there will be many applications for the ReSMAP web server, including rapid screening of IDR sequences for membrane association.
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Affiliation(s)
- Sanbo Qin
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Alan Hicks
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Souvik Dey
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Ramesh Prasad
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Huan-Xiang Zhou
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
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6
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Sun J, Rutherford ST, Silhavy TJ, Huang KC. Physical properties of the bacterial outer membrane. Nat Rev Microbiol 2022; 20:236-248. [PMID: 34732874 PMCID: PMC8934262 DOI: 10.1038/s41579-021-00638-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2021] [Indexed: 11/09/2022]
Abstract
It has long been appreciated that the Gram-negative outer membrane acts as a permeability barrier, but recent studies have uncovered a more expansive and versatile role for the outer membrane in cellular physiology and viability. Owing to recent developments in microfluidics and microscopy, the structural, rheological and mechanical properties of the outer membrane are becoming apparent across multiple scales. In this Review, we discuss experimental and computational studies that have revealed key molecular factors and interactions that give rise to the spatial organization, limited diffusivity and stress-bearing capacity of the outer membrane. These physical properties suggest broad connections between cellular structure and physiology, and we explore future prospects for further elucidation of the implications of outer membrane construction for cellular fitness and survival.
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Affiliation(s)
- Jiawei Sun
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Steven T. Rutherford
- Department of Infectious Diseases, Genentech Inc., South San Francisco, CA 94080, USA,To whom correspondence should be addressed: , ,
| | - Thomas J. Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA,To whom correspondence should be addressed: , ,
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, USA. .,Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
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7
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Hu M, Zhao H, Yang B, Yang S, Liu H, Tian H, Shui G, Chen Z, E L, Lai J, Song W. ZmCTLP1 is required for the maintenance of lipid homeostasis and the basal endosperm transfer layer in maize kernels. THE NEW PHYTOLOGIST 2021; 232:2384-2399. [PMID: 34559890 PMCID: PMC9292782 DOI: 10.1111/nph.17754] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 09/15/2021] [Indexed: 05/26/2023]
Abstract
Maize kernel weight is influenced by the unloading of nutrients from the maternal placenta and their passage through the transfer tissue of the basal endosperm transfer layer (BETL) and the basal intermediate zone (BIZ) to the upper part of the endosperm. Here, we show that Small kernel 10 (Smk10) encodes a choline transporter-like protein 1 (ZmCTLP1) that facilitates choline uptake and is located in the trans-Golgi network (TGN). Its loss of function results in reduced choline content, leading to smaller kernels with a lower starch content. Mutation of ZmCTLP1 disrupts membrane lipid homeostasis and the normal development of wall in-growths. Expression levels of Mn1 and ZmSWEET4c, two kernel filling-related genes, are downregulated in the smk10, which is likely to be one of the major causes of incompletely differentiated transfer cells. Mutation of ZmCTLP1 also reduces the number of plasmodesmata (PD) in transfer cells, indicating that the smk10 mutant is impaired in PD formation. Intriguingly, we also observed premature cell death in the BETL and BIZ of the smk10 mutant. Together, our results suggest that ZmCTLP1-mediated choline transport affects kernel development, highlighting its important role in lipid homeostasis, wall in-growth formation and PD development in transfer cells.
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Affiliation(s)
- Mingjian Hu
- State Key Laboratory of Plant Physiology and Biochemistry and National Maize Improvement CenterDepartment of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
| | - Haiming Zhao
- State Key Laboratory of Plant Physiology and Biochemistry and National Maize Improvement CenterDepartment of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
| | - Bo Yang
- State Key Laboratory of Plant Physiology and Biochemistry and National Maize Improvement CenterDepartment of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
| | - Shuang Yang
- State Key Laboratory of Plant Physiology and Biochemistry and National Maize Improvement CenterDepartment of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
| | - Haihong Liu
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
| | - He Tian
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing100101China
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing100101China
| | - Zongliang Chen
- State Key Laboratory of Plant Physiology and Biochemistry and National Maize Improvement CenterDepartment of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
- Waksman Institute of MicrobiologyRutgers UniversityPiscatawayNJ08854‐8020USA
| | - Lizhu E
- State Key Laboratory of Plant Physiology and Biochemistry and National Maize Improvement CenterDepartment of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
- Center for Crop Functional Genomics and Molecular BreedingChina Agricultural UniversityBeijing100193China
| | - Jinsheng Lai
- State Key Laboratory of Plant Physiology and Biochemistry and National Maize Improvement CenterDepartment of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
- Center for Crop Functional Genomics and Molecular BreedingChina Agricultural UniversityBeijing100193China
| | - Weibin Song
- State Key Laboratory of Plant Physiology and Biochemistry and National Maize Improvement CenterDepartment of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
- Center for Crop Functional Genomics and Molecular BreedingChina Agricultural UniversityBeijing100193China
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8
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Abstract
The evolution of lipids in nanoscience exemplifies the powerful coupling of advances in science and technology. Here, we describe two waves of discovery and innovation in lipid materials: one historical and one still building. The first wave leveraged the relatively simple capability for lipids to orient at interfaces, building layers of functional groups. This simple form of building with atoms yielded a stunning range of technologies: lubricant additives that dramatically extended machine lifetimes, molecules that enabled selective ore extraction in mining, and soaps that improved human health. It also set the stage for many areas of modern nanoscience. The second wave of lipid materials, still growing, uses the more complex toolkits lipids offer for building with atoms, including controlling atomic environment to control function (e.g., pKa tuning) and the generation of more arbitrary two-dimensional and three-dimensional structures, including lipid nanoparticles for COVID-19 mRNA vaccines.
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Affiliation(s)
- Anni Shi
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Shelley A Claridge
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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9
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Theoretical Three-Dimensional Zinc Complexes with Glutathione, Amino Acids and Flavonoids. STRESSES 2021. [DOI: 10.3390/stresses1030011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Zinc plays an important role in the regulation of many cellular functions; it is a signaling molecule involved in the transduction of several cascades in response to intra and extracellular stimuli. Labile zinc is a small fraction of total intracellular zinc, that is loosely bound to proteins and is easily interchangeable. At the cellular level, several molecules can bind labile zinc and promote its passage across lipophilic membranes. Such molecules are known as ionophores. Several of these compounds are known in the scientific literature, but most of them can be harmful to human health and are therefore not allowed for medical use. We here performed a theoretical three-dimensional study of known zinc ionophores, together with a computational energetic study and propose that some dietary flavonoids, glutathione and amino acids could form zinc complexes and facilitate the transport of zinc, with the possible biological implications and potential health benefits of these natural compounds. The study is based on obtaining a molecular conformational structure of the zinc complexes with the lowest possible energy content. The discovery of novel substances that act as zinc ionophores is an attractive research topic that offers exciting opportunities in medicinal chemistry. We propose that these novel complexes could be promising candidates for drug design to provide new solutions for conditions and diseases related to zinc deficiency or impairment derived from the dysregulation of this important metal.
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10
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Godoy-Hernandez A, McMillan DGG. The Profound Influence of Lipid Composition on the Catalysis of the Drug Target NADH Type II Oxidoreductase. MEMBRANES 2021; 11:membranes11050363. [PMID: 34067848 PMCID: PMC8156991 DOI: 10.3390/membranes11050363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 11/25/2022]
Abstract
Lipids play a pivotal role in cellular respiration, providing the natural environment in which an oxidoreductase interacts with the quinone pool. To date, it is generally accepted that negatively charged lipids play a major role in the activity of quinone oxidoreductases. By changing lipid compositions when assaying a type II NADH:quinone oxidoreductase, we demonstrate that phosphatidylethanolamine has an essential role in substrate binding and catalysis. We also reveal the importance of acyl chain composition, specifically c14:0, on membrane-bound quinone-mediated catalysis. This demonstrates that oxidoreductase lipid specificity is more diverse than originally thought and that the lipid environment plays an important role in the physiological catalysis of membrane-bound oxidoreductases.
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11
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Chwastek G, Surma MA, Rizk S, Grosser D, Lavrynenko O, Rucińska M, Jambor H, Sáenz J. Principles of Membrane Adaptation Revealed through Environmentally Induced Bacterial Lipidome Remodeling. Cell Rep 2021; 32:108165. [PMID: 32966790 DOI: 10.1016/j.celrep.2020.108165] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/20/2020] [Accepted: 08/27/2020] [Indexed: 12/17/2022] Open
Abstract
Cells, from microbes to mammals, adapt their membrane lipid composition in response to environmental changes to maintain optimal properties. Global patterns of lipidome remodeling are poorly understood, particularly in organisms with simple lipid compositions that can provide insight into fundamental principles of membrane adaptation. Using shotgun lipidomics, we examine the simple yet, as we show here, adaptive lipidome of the plant-associated Gram-negative bacterium Methylobacterium extorquens. We observe that minimally 11 lipids account for 90% of total variability, thus constraining the upper limit of variable lipids required for an adaptive living membrane. Through lipid features analysis, we reveal that acyl chain remodeling is not evenly distributed across lipid classes, resulting in headgroup-specific effects of acyl chain variability on membrane properties. Results herein implicate headgroup-specific acyl chain remodeling as a mechanism for fine-tuning the membrane's physical state and provide a resource for using M. extorquens to explore the design principles of living membranes.
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Affiliation(s)
- Grzegorz Chwastek
- Technische Universität Dresden, B CUBE, Tatzberg 41, Dresden, Germany
| | | | - Sandra Rizk
- Technische Universität Dresden, B CUBE, Tatzberg 41, Dresden, Germany
| | - Daniel Grosser
- DZD-Paul Langerhans Institute Dresden, Fetscherstraße 74, Dresden, Germany
| | - Oksana Lavrynenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, Dresden, Germany
| | | | - Helena Jambor
- Technische Universität Dresden, Medizinische Fakultät, Fetscherstraße 74, Dresden, Germany
| | - James Sáenz
- Technische Universität Dresden, B CUBE, Tatzberg 41, Dresden, Germany.
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12
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Chadda R, Bernhardt N, Kelley EG, Teixeira SC, Griffith K, Gil-Ley A, Öztürk TN, Hughes LE, Forsythe A, Krishnamani V, Faraldo-Gómez JD, Robertson JL. Membrane transporter dimerization driven by differential lipid solvation energetics of dissociated and associated states. eLife 2021; 10:63288. [PMID: 33825681 PMCID: PMC8116059 DOI: 10.7554/elife.63288] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 04/06/2021] [Indexed: 12/22/2022] Open
Abstract
Over two-thirds of integral membrane proteins of known structure assemble into oligomers. Yet, the forces that drive the association of these proteins remain to be delineated, as the lipid bilayer is a solvent environment that is both structurally and chemically complex. In this study, we reveal how the lipid solvent defines the dimerization equilibrium of the CLC-ec1 Cl-/H+ antiporter. Integrating experimental and computational approaches, we show that monomers associate to avoid a thinned-membrane defect formed by hydrophobic mismatch at their exposed dimerization interfaces. In this defect, lipids are strongly tilted and less densely packed than in the bulk, with a larger degree of entanglement between opposing leaflets and greater water penetration into the bilayer interior. Dimerization restores the membrane to a near-native state and therefore, appears to be driven by the larger free-energy cost of lipid solvation of the dissociated protomers. Supporting this theory, we demonstrate that addition of short-chain lipids strongly shifts the dimerization equilibrium toward the monomeric state, and show that the cause of this effect is that these lipids preferentially solvate the defect. Importantly, we show that this shift requires only minimal quantities of short-chain lipids, with no measurable impact on either the macroscopic physical state of the membrane or the protein's biological function. Based on these observations, we posit that free-energy differentials for local lipid solvation define membrane-protein association equilibria. With this, we argue that preferential lipid solvation is a plausible cellular mechanism for lipid regulation of oligomerization processes, as it can occur at low concentrations and does not require global changes in membrane properties. A cell’s outer membrane is made of molecules called lipids, which band together to form a flexible thin film, just two molecules thick. This membrane is dotted with proteins that transport materials in to and out of cells. Most of these membrane proteins join with other proteins to form structures known as oligomers. Except, how membrane-bound proteins assemble into oligomers – the physical forces driving these molecules to take shape – remains unclear. This is partly because the structural, physical and chemical properties of fat-like lipid membranes are radically different to the cell’s watery interior. Consequently, the conditions under which membrane oligomers form are distinct from those surrounding proteins inside cells. Membrane proteins are also more difficult to study and characterize than water-soluble proteins inside the cell, and yet many therapeutic drugs such as antibiotics specifically target membrane proteins. Overall, our understanding of how the unique properties of lipid membranes affect the formation of protein structures embedded within, is lacking and warrants further investigation. Now, Chadda, Bernhardt et al. focused on one membrane protein, known as CLC, which tends to exist in pairs – or dimers. To understand why these proteins form dimers (a process called dimerization) Chadda, Bernhardt et al. first used computer simulations, and then validated the findings in experimental tests. These complementary approaches demonstrated that the main reason CLC proteins ‘dimerize’ lies in their interaction with the lipid membrane, and not the attraction of one protein to its partner. When CLC proteins are on their own, they deform the surrounding membrane and create structural defects that put the membrane under strain. But when two CLC proteins join as a dimer, this membrane strain disappears – making dimerization the more stable and energetically favorable option. Chadda, Bernhardt et al. also showed that with the addition of a few certain lipids, specifically smaller lipids, cell membranes become more tolerant of protein-induced structural changes. This might explain how cells could use various lipids to fine-tune the activity of membrane proteins by controlling how oligomers form. However, the theory needs to be examined further. Altogether, this work has provided fundamental insights into the physical forces shaping membrane-bound proteins, relevant to researchers studying cell biology and pharmacology alike.
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Affiliation(s)
- Rahul Chadda
- Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, United States
| | - Nathan Bernhardt
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, United States
| | - Susana Cm Teixeira
- NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, United States.,Center for Neutron Science, Chemical and Biomolecular Engineering, University of Delaware, Newark, United States
| | - Kacie Griffith
- Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, United States
| | - Alejandro Gil-Ley
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States.,Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, United States
| | - Tuğba N Öztürk
- Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, United States
| | - Lauren E Hughes
- Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, United States
| | - Ana Forsythe
- Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, United States
| | - Venkatramanan Krishnamani
- Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, United States
| | - José D Faraldo-Gómez
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Janice L Robertson
- Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, United States
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13
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Rosário-Ferreira N, Marques-Pereira C, Gouveia RP, Mourão J, Moreira IS. Guardians of the Cell: State-of-the-Art of Membrane Proteins from a Computational Point-of-View. Methods Mol Biol 2021; 2315:3-28. [PMID: 34302667 DOI: 10.1007/978-1-0716-1468-6_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Membrane proteins (MPs) encompass a large family of proteins with distinct cellular functions, and although representing over 50% of existing pharmaceutical drug targets, their structural and functional information is still very scarce. Over the last years, in silico analysis and algorithm development were essential to characterize MPs and overcome some limitations of experimental approaches. The optimization and improvement of these methods remain an ongoing process, with key advances in MPs' structure, folding, and interface prediction being continuously tackled. Herein, we discuss the latest trends in computational methods toward a deeper understanding of the atomistic and mechanistic details of MPs.
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Affiliation(s)
- Nícia Rosário-Ferreira
- Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, Coimbra, Portugal.,Center for Neuroscience and Cell Biology, Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
| | - Catarina Marques-Pereira
- Center for Neuroscience and Cell Biology, Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,PhD Programme in Experimental Biology and Biomedicine, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Coimbra, Portugal
| | - Raquel P Gouveia
- Center for Neuroscience and Cell Biology, Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
| | - Joana Mourão
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Irina S Moreira
- Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
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14
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Sahu ID. Conformational Dynamics of the Extracellular Loop of BtuB in Whole Cells. Biophys J 2020; 119:1470-1471. [PMID: 33031737 DOI: 10.1016/j.bpj.2020.09.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 09/15/2020] [Indexed: 11/24/2022] Open
Affiliation(s)
- Indra D Sahu
- Natural Science Division, Campbellsville University, Campbellsville, Kentucky.
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15
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Structural cavities are critical to balancing stability and activity of a membrane-integral enzyme. Proc Natl Acad Sci U S A 2020; 117:22146-22156. [PMID: 32848056 DOI: 10.1073/pnas.1917770117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Packing interaction is a critical driving force in the folding of helical membrane proteins. Despite the importance, packing defects (i.e., cavities including voids, pockets, and pores) are prevalent in membrane-integral enzymes, channels, transporters, and receptors, playing essential roles in function. Then, a question arises regarding how the two competing requirements, packing for stability vs. cavities for function, are reconciled in membrane protein structures. Here, using the intramembrane protease GlpG of Escherichia coli as a model and cavity-filling mutation as a probe, we tested the impacts of native cavities on the thermodynamic stability and function of a membrane protein. We find several stabilizing mutations which induce substantial activity reduction without distorting the active site. Notably, these mutations are all mapped onto the regions of conformational flexibility and functional importance, indicating that the cavities facilitate functional movement of GlpG while compromising the stability. Experiment and molecular dynamics simulation suggest that the stabilization is induced by the coupling between enhanced protein packing and weakly unfavorable lipid desolvation, or solely by favorable lipid solvation on the cavities. Our result suggests that, stabilized by the relatively weak interactions with lipids, cavities are accommodated in membrane proteins without severe energetic cost, which, in turn, serve as a platform to fine-tune the balance between stability and flexibility for optimal activity.
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16
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Yuan L, Zhao Y, Sun XL. Sialidase substrates for Sialdiase assays - activity, specificity, quantification and inhibition. Glycoconj J 2020; 37:513-531. [PMID: 32813176 DOI: 10.1007/s10719-020-09940-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/08/2020] [Accepted: 08/06/2020] [Indexed: 12/01/2022]
Abstract
Sialidases are glycosidases responsible for the removal of sialic acid (Sia) residues (desialylation) from glycan portions of either glycoproteins or glycolipids. By desialylation, sialidases are able to modulate the functionality and stability of the Sia-containing molecules and are involved in both physiological and pathological pathways. Therefore, evaluation of sialidase activity and specificity is important for understanding the biological significance of desialylation by sialidases and its function and the related molecular mechanisms of the physiological and pathological pathways. In addition, it is essential for developing novel mechanisms and approaches for disease treatment and diagnosis and pathogen detection as well. This review summarizes the most recent sialidase substrates for evaluating sialidase activity and specificity and screening sialidase inhibitors, including (i) general sialidase substrates, (ii) specific sialidase substrates, (iii) native sialidase substrates and (iv) cellular sialidase substrates. This review also provides a brief introduction of recent instrumental methods for quantifying the sialidase activity, such as UV, fluorescence, HPLC and LC-MS methods.
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Affiliation(s)
- Lei Yuan
- Department of Chemistry, Chemical and Biomedical Engineering and Center for Gene Regulation in Health and Disease (GRHD), Cleveland State University, 2121 Euclid Avenue, Cleveland, OH, 44115, USA.,School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang, 110016, People's Republic of China
| | - Yu Zhao
- Department of Chemistry, Chemical and Biomedical Engineering and Center for Gene Regulation in Health and Disease (GRHD), Cleveland State University, 2121 Euclid Avenue, Cleveland, OH, 44115, USA
| | - Xue-Long Sun
- Department of Chemistry, Chemical and Biomedical Engineering and Center for Gene Regulation in Health and Disease (GRHD), Cleveland State University, 2121 Euclid Avenue, Cleveland, OH, 44115, USA.
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17
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Iyer SS, Srivastava A. Degeneracy in molecular scale organization of biological membranes. SOFT MATTER 2020; 16:6752-6764. [PMID: 32628232 DOI: 10.1039/d0sm00619j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The scale-rich spatiotemporal organization in biological membranes has its origin in the differential inter- and intra-molecular interactions among their constituents. In this work, we explore the molecular-origin behind that variety and possible degeneracy in lateral organization in membranes. For our study, we post-process microsecond long all-atom molecular dynamics trajectories for three systems that exhibit fluid phase coexistence: (i) PSM/POPC/Chol (0.47/0.32/0.21), (ii) PSM/DOPC/Chol (0.43/0.38/0.19) and (iii) DPPC/DOPC/Chol (0.37/0.36/0.27). To distinguish the liquid ordered and disordered regions at molecular scales, we calculate the degree of non-affineness of individual lipids in their neighbourhood and track their topological rearrangements. Disconnectivity graph analysis with respect to membrane organization shows that the DPPC/DOPC/Chol and PSM/DOPC/Chol systems exhibit funnel-like energy landscapes as opposed to a highly frustrated energy landscape for the more biomimetic PSM/POPC/Chol system. We use these measurements to develop a continuous lattice Hamiltonian and evolve that using Monte Carlo simulated annealing to explore the possibility of structural degeneracy in membrane organization. Our data show that model membranes with lipid constituents that are biomimetic (PSM/POPC/Chol) have the ability to access a large range of membrane sub-structure space (higher degeneracy) as compared to the other two systems, which form only one kind of substructure even with changing composition. Since the spatiotemporal organization in biological membranes dictates the "molecular encounters" and in turn larger scale biological processes such as molecular transport, trafficking and cellular signalling, we posit that this structural degeneracy could enable access to a larger repository to functionally important molecular organization in systems with physiologically relevant compositions.
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Affiliation(s)
- Sahithya S Iyer
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India.
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18
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Inada M, Kinoshita M, Matsumori N. Archaeal Glycolipid S-TGA-1 Is Crucial for Trimer Formation and Photocycle Activity of Bacteriorhodopsin. ACS Chem Biol 2020; 15:197-204. [PMID: 31647217 DOI: 10.1021/acschembio.9b00756] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although it has been demonstrated that membrane proteins (MPs) require lipids to ensure their structural and functional integrity, details on how lipid-MP interactions regulate MPs are still unclear. Recently, we developed a concise method for quantitatively evaluating lipid-MP interactions and applied it to bacteriorhodopsin (bR), a halobacterial MP that forms trimers and acts as a light-driven proton pump. Consequently, we found that the halobacterial glycolipid, S-TGA-1, has the highest affinity for bR, among other lipids. In this study, we examined the effects of S-TGA-1 on bR via visible circular dichroism spectroscopy, flash photolysis, and proton influx measurement. The results showed that S-TGA-1 efficiently promotes trimer formation, photocycle, and proton pumping in bR. Our data also suggested that the bR photocycle is restored as a consequence of the trimerization induced by the lipid. This study demonstrates clearly that lipids specifically interacting with MPs can have significant impacts on MP structure and/or function. The methodology adopted in our studies can be applied to other MPs and will help elucidate the physiological functions of lipids in terms of lipid-MP interactions, thus accelerating "lipid chemical biology" studies.
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Affiliation(s)
- Masataka Inada
- Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Masanao Kinoshita
- Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Nobuaki Matsumori
- Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
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19
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Ding X, Fu R, Tian F. De novo resonance assignment of the transmembrane domain of LR11/SorLA in E. coli membranes. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 310:106639. [PMID: 31734618 PMCID: PMC6935515 DOI: 10.1016/j.jmr.2019.106639] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/28/2019] [Accepted: 10/30/2019] [Indexed: 05/17/2023]
Abstract
Membrane proteins perform many important cellular functions. Historically, structural studies of these proteins have been conducted in detergent preparations and synthetic lipid bilayers. More recently, magic-angle-spinning (MAS) solid-state NMR has been employed to analyze membrane proteins in native membrane environments, but resonance assignments with this technique remain challenging due to limited spectral resolution and high resonance degeneracy. To tackle this issue, we combine reverse labeling of amino acids, frequency-selective dipolar dephasing, and NMR difference spectroscopy. These methods have resulted in nearly complete resonance assignments of the transmembrane domain of human LR11 (SorLA) protein in E. coli membranes. To reduce background signals from E. coli lipids and proteins and improve spectral sensitivity, we effectively utilize amylose affinity chromatography to prepare membrane vesicles when MBP is included as a fusion partner in the expression construct.
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Affiliation(s)
- Xiaoyan Ding
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, Hershey, PA 17033, USA
| | - Riqiang Fu
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., Tallahassee, FL 32310, USA.
| | - Fang Tian
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, Hershey, PA 17033, USA.
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20
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Investigation of substrate specificity of sialidases with membrane mimetic glycoconjugates. Glycoconj J 2019; 37:175-185. [PMID: 31802374 DOI: 10.1007/s10719-019-09895-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/20/2019] [Accepted: 11/06/2019] [Indexed: 01/17/2023]
Abstract
Sialidases or neuraminidases play important roles in various physiological and pathological processes by cleaving terminal sialic acids (Sias) (desialylation) from the glycans of both glycoproteins and glycolipids. To understand the biological significance of desialylation by sialidases, it is important to investigate enzyme specificity with native substrate in biological membrane of cells. Herein, we report a membrane-mimicking system with liposome ganglioside conjugates containing different lipids for evaluating substrate specificity of sialidase and the lipid effect on the enzyme activity. Briefly, liposomes of phosphatidylcholine (PC) and cholesterol with ganglioside (GM3 or GM1) along with different percentage of phosphatidylserine (PS) or phosphatidylethanolamine (PE) were prepared and characterized. Their desialylation profiles with Arthrobacter ureafaciens (bacterial) sialidase and H1N1 (influenza viral) sialidase were quantified by HPLC method. A diversity of substrate preference was found for both bacterial and viral sialidase to the liposome ganglioside conjugate platform. The apparent Km and Vmax were dependent on the type of lipid. These results indicate that the intrinsic characteristics of the membrane-like system affect the sialidase specificity and activity. This biomimetic substrate provides a better tool for unravelling the substrate specificity and the biological function of sialidases and for screening of functional sialidase inhibitors as well.
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21
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Prokaryotic and Mitochondrial Lipids: A Survey of Evolutionary Origins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019. [PMID: 31502197 DOI: 10.1007/978-3-030-21162-2_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
Mitochondria and bacteria share a myriad of properties since it is believed that the powerhouses of the eukaryotic cell have evolved from a prokaryotic origin. Ribosomal RNA sequences, DNA architecture and metabolism are strikingly similar in these two entities. Proteins and nucleic acids have been a hallmark for comparison between mitochondria and prokaryotes. In this chapter, similarities (and differences) between mitochondrial and prokaryotic membranes are addressed with a focus on structure-function relationship of different lipid classes. In order to be suitable for the theme of the book, a special emphasis is reserved to the effects of bioactive sphingolipids, mainly ceramide, on mitochondrial membranes and their roles in initiating programmed cell death.
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22
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Sanders CR. Life During Wartime: A Personal Recollection of the Circa 1990 Prestegard Lab and Its Contributions to Membrane Biophysics. J Membr Biol 2019; 252:541-548. [PMID: 31471644 DOI: 10.1007/s00232-019-00090-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 08/16/2019] [Indexed: 12/14/2022]
Abstract
A subjective account is presented of challenges and excitement of being a postdoctoral trainee in the lab of James H. Prestegard at Yale University in New Haven, Connecticut from 1989 to 1991. This includes accounts of the early development of bicelles and of oriented sample NMR results that contributed to our modern understanding of the properties of the water-lipid interface of disordered phase biological membranes.
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Affiliation(s)
- Charles R Sanders
- Department of Biochemistry, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, 37240-7917, USA.
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23
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Marinko J, Huang H, Penn WD, Capra JA, Schlebach JP, Sanders CR. Folding and Misfolding of Human Membrane Proteins in Health and Disease: From Single Molecules to Cellular Proteostasis. Chem Rev 2019; 119:5537-5606. [PMID: 30608666 PMCID: PMC6506414 DOI: 10.1021/acs.chemrev.8b00532] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Indexed: 12/13/2022]
Abstract
Advances over the past 25 years have revealed much about how the structural properties of membranes and associated proteins are linked to the thermodynamics and kinetics of membrane protein (MP) folding. At the same time biochemical progress has outlined how cellular proteostasis networks mediate MP folding and manage misfolding in the cell. When combined with results from genomic sequencing, these studies have established paradigms for how MP folding and misfolding are linked to the molecular etiologies of a variety of diseases. This emerging framework has paved the way for the development of a new class of small molecule "pharmacological chaperones" that bind to and stabilize misfolded MP variants, some of which are now in clinical use. In this review, we comprehensively outline current perspectives on the folding and misfolding of integral MPs as well as the mechanisms of cellular MP quality control. Based on these perspectives, we highlight new opportunities for innovations that bridge our molecular understanding of the energetics of MP folding with the nuanced complexity of biological systems. Given the many linkages between MP misfolding and human disease, we also examine some of the exciting opportunities to leverage these advances to address emerging challenges in the development of therapeutics and precision medicine.
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Affiliation(s)
- Justin
T. Marinko
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Hui Huang
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Wesley D. Penn
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - John A. Capra
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department
of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37245, United States
| | - Jonathan P. Schlebach
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Charles R. Sanders
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
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24
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Huff HC, Maroutsos D, Das A. Lipid composition and macromolecular crowding effects on CYP2J2-mediated drug metabolism in nanodiscs. Protein Sci 2019; 28:928-940. [PMID: 30861250 DOI: 10.1002/pro.3603] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/11/2019] [Indexed: 01/13/2023]
Abstract
Lipid composition and macromolecular crowding are key external effectors of protein activity and stability whose role varies between different proteins. Therefore, it is imperative to study their effects on individual protein function. CYP2J2 is a membrane-bound cytochrome P450 in the heart involved in the metabolism of fatty acids and xenobiotics. In order to facilitate this metabolism, cytochrome P450 reductase (CPR), transfers electrons to CYP2J2 from NADPH. Herein, we use nanodiscs to show that lipid composition of the membrane bilayer affects substrate metabolism of the CYP2J2-CPR nanodisc (ND) system. Differential effects on both NADPH oxidation and substrate metabolism by CYP2J2-CPR are dependent on the lipid composition. For instance, sphingomyelin containing nanodiscs produced more secondary substrate metabolites than discs of other lipid compositions, implying a possible conformational change leading to processive metabolism. Furthermore, we demonstrate that macromolecular crowding plays a role in the lipid-solubilized CYP2J2-CPR system by increasing the Km and decreasing the Vmax , and effect that is size-dependent. Crowding also affects the CYP2J2-CPR-ND system by decreasing both the Km and Vmax for Dextran-based macromolecular crowding agents, implying an increase in substrate affinity but a lack of metabolism. Finally, protein denaturation studies show that crowding agents destabilize CYP2J2, while the multidomain protein CPR is stabilized. Overall, these studies are the first report on the role of the surrounding lipid environment and macromolecular crowding in modulating enzymatic function of CYP2J2-CPR membrane protein system.
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Affiliation(s)
- Hannah C Huff
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Demetri Maroutsos
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Aditi Das
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Beckman Institute for Advanced Science and Technology, Division of Nutritional Science, Neuroscience Program, and Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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25
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Inada M, Kinoshita M, Sumino A, Oiki S, Matsumori N. A concise method for quantitative analysis of interactions between lipids and membrane proteins. Anal Chim Acta 2019; 1059:103-112. [PMID: 30876624 DOI: 10.1016/j.aca.2019.01.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 01/17/2019] [Accepted: 01/18/2019] [Indexed: 01/31/2023]
Abstract
Although interactions between lipids and membrane proteins (MPs) have been considered crucially important for understanding the functions of lipids, lack of useful and convincing experimental methods has hampered the analysis of the interactions. Here, we developed a surface plasmon resonance (SPR)-based concise method for quantitative analysis of lipid-MP interactions, coating the sensor chip surface with self-assembled monolayer (SAM) with C6-chain. To develop this method, we used bacteriorhodopsin (bR) as an MP, and examined its interaction with various types of lipids. The merits of using C6-SAM-modified sensor chip are as follows: (1) alkyl-chains of SAM confer a better immobilization of MPs because of the efficient preconcentration due to hydrophobic contacts; (2) SAM provides immobilized MPs with a partial membranous environment, which is important for the stabilization of MPs; and (3) a thinner C6-SAM layer (1 nm) compared with MP size forces the MP to bulge outward from the SAM surface, allowing extraneously injected lipids to be accessible to the hydrophobic transmembrane regions. Actually, the amount of bR immobilized on C6-SAM is 10 times higher than that on a hydrophilic CM5 sensor chip, and AFM observations confirmed that bR molecules are exposed on the SAM surface. Of the lipids tested, S-TGA-1, a halobacterium-derived glycolipid, had the highest specificity to bR with a nanomolar dissociation constant. This is consistent with the reported co-crystal structure that indicates the formation of several intermolecular hydrogen bonds. Therefore, we not only reproduced the specific lipid-bR recognition, but also succeeded in its quantitative evaluation, demonstrating the validity and utility of this method.
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Affiliation(s)
- Masataka Inada
- Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Masanao Kinoshita
- Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Ayumi Sumino
- Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan; High-speed AFM for Biological Application Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, 920-1192, Japan; Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, 920-1192, Japan
| | - Shigetoshi Oiki
- Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan
| | - Nobuaki Matsumori
- Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
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26
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Membrane properties that shape the evolution of membrane enzymes. Curr Opin Struct Biol 2018; 51:80-91. [PMID: 29597094 DOI: 10.1016/j.sbi.2018.03.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 02/07/2023]
Abstract
Spectacular recent progress in structural biology has led to determination of the structures of many integral membrane enzymes that catalyze reactions in which at least one substrate also is membrane bound. A pattern of results seems to be emerging in which the active site chemistry of these enzymes is usually found to be analogous to what is observed for water soluble enzymes catalyzing the same reaction types. However, in light of the chemical, structural, and physical complexity of cellular membranes plus the presence of transmembrane gradients and potentials, these enzymes may be subject to membrane-specific regulatory mechanisms that are only now beginning to be uncovered. We review the membrane-specific environmental traits that shape the evolution of membrane-embedded biocatalysts.
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27
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Bondarenko V, Wells M, Xu Y, Tang P. Solution NMR Studies of Anesthetic Interactions with Ion Channels. Methods Enzymol 2018; 603:49-66. [PMID: 29673534 DOI: 10.1016/bs.mie.2018.01.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
NMR spectroscopy is one of the major tools to provide atomic resolution protein structural information. It has been used to elucidate the molecular details of interactions between anesthetics and ion channels, to identify anesthetic binding sites, and to characterize channel dynamics and changes introduced by anesthetics. In this chapter, we present solution NMR methods essential for investigating interactions between ion channels and general anesthetics, including both volatile and intravenous anesthetics. Case studies are provided with a focus on pentameric ligand-gated ion channels and the voltage-gated sodium channel NaChBac.
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Affiliation(s)
- Vasyl Bondarenko
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Marta Wells
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Yan Xu
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Pei Tang
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
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28
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Malcolm DW, Freeberg MAT, Wang Y, Sims KR, Awad HA, Benoit DSW. Diblock Copolymer Hydrophobicity Facilitates Efficient Gene Silencing and Cytocompatible Nanoparticle-Mediated siRNA Delivery to Musculoskeletal Cell Types. Biomacromolecules 2017; 18:3753-3765. [PMID: 28960967 DOI: 10.1021/acs.biomac.7b01349] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
pH-responsive diblock copolymers provide tailorable nanoparticle (NP) architecture and chemistry critical for siRNA delivery. Here, diblock polymers varying in first (corona) and second (core) block molecular weight (Mn), corona/core ratio, and core hydrophobicity (%BMA) were synthesized to determine their effect on siRNA delivery in murine tenocytes (mTenocyte) and murine and human mesenchymal stem cells (mMSC and hMSCs, respectively). NP-mediated siRNA uptake, gene silencing, and cytocompatibility were quantified. Uptake is positively correlated with first block Mn in mTenocytes and hMSCs (p ≤ 0.0005). All NP resulted in significant gene silencing that was positively correlated with %BMA (p < 0.05) in all cell types. Cytocompatibility was reduced in mTenocytes compared to MSCs (p < 0.0001). %BMA was positively correlated with cytocompatibility in MSCs (p < 0.05), suggesting stable NP are more cytocompatible. Overall, this study shows that NP-siRNA cytocompatibility is cell type dependent, and hydrophobicity (%BMA) is the critical diblock copolymer property for efficient gene silencing in musculoskeletal cell types.
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Affiliation(s)
| | | | | | - Kenneth R Sims
- Translational Biomedical Science, University of Rochester School of Medicine and Dentistry , Rochester, New York, United States
| | - Hani A Awad
- Department of Orthopedics, University of Rochester Medical Center , Rochester, New York, United States
| | - Danielle S W Benoit
- Department of Orthopedics, University of Rochester Medical Center , Rochester, New York, United States
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29
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Khanna R, Kumar K, Roy R. A case study of primary malignancy of buccal mucosa using proton HR-MAS NMR spectroscopy on tissue specimens. J Oral Biol Craniofac Res 2017; 8:68-72. [PMID: 29556467 DOI: 10.1016/j.jobcr.2017.09.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 09/28/2017] [Indexed: 10/18/2022] Open
Abstract
The diagnosis and confirmation of oral SCC (squamous cell carcinoma) is still dependent on histopathology report in spite of development of radiological investigations. It is, thus important to understand the underlying molecular mechanisms and how the alterations in metabolic pathways effect the tumor development and progression. The simultaneous and comprehensive information about the presence and absence of small molecule metabolites and their relative concentrations has been provided by 1H HR-MAS NMR spectroscopy on tissue specimens. In this paper a unique case study was presented in order to correlate histological and NMR spectroscopic findings. The patient's initially lesion was found to be non-malignant in nature based on histological findings but its periodic localized recurrence even after laser ablation prompted us to perform HR-MAS based analysis and its role in identifying the metabolic alterations in known pathways occurring during its progressions. Thus it was confirmed after analysis that HR-MAS NMR can also be used as an analytical tool which is reliable in order to distinguish between malignant and non-malignant tissues, in combination with histopathology.
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Affiliation(s)
- Rohit Khanna
- Department of Orthodontics and Dentofacial Orthopaedics, Babu Banarsi Das College of Dental Sciences, Lucknow, India
| | - Kapila Kumar
- Department of Oral & Maxillofacial Surgery, King George's Medical College, Lucknow, India
| | - Raja Roy
- Centre of Biomedical Research, formerly Centre of Biomedical Magnetic Resonance, Raebareilly Road, Lucknow, India
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30
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Stroobants K, Kumita JR, Harris NJ, Chirgadze DY, Dobson CM, Booth PJ, Vendruscolo M. Amyloid-like Fibrils from an α-Helical Transmembrane Protein. Biochemistry 2017; 56:3225-3233. [PMID: 28493669 PMCID: PMC5489960 DOI: 10.1021/acs.biochem.7b00157] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The propensity to
misfold and self-assemble into stable aggregates
is increasingly being recognized as a common feature of protein molecules.
Our understanding of this phenomenon and of its links with human disease
has improved substantially over the past two decades. Studies thus
far, however, have been almost exclusively focused on cytosolic proteins,
resulting in a lack of detailed information about the misfolding and
aggregation of membrane proteins. As a consequence, although such
proteins make up approximately 30% of the human proteome and have
high propensities to aggregate, relatively little is known about the
biophysical nature of their assemblies. To shed light on this issue,
we have studied as a model system an archetypical representative of
the ubiquitous major facilitator superfamily, the Escherichia
coli lactose permease (LacY). By using a combination of established
indicators of cross-β structure and morphology, including the
amyloid diagnostic dye thioflavin-T, circular dichroism spectroscopy,
Fourier transform infrared spectroscopy, X-ray fiber diffraction,
and transmission electron microscopy, we show that LacY can form amyloid-like
fibrils under destabilizing conditions. These results indicate that
transmembrane α-helical proteins, similarly to cytosolic proteins,
have the ability to adopt this generic state.
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Affiliation(s)
- Karen Stroobants
- Department of Chemistry, University of Cambridge , Cambridge CB2 1EW, U.K
| | - Janet R Kumita
- Department of Chemistry, University of Cambridge , Cambridge CB2 1EW, U.K
| | - Nicola J Harris
- Department of Chemistry, King's College London , London SE1 1DB, U.K
| | - Dimitri Y Chirgadze
- Department of Biochemistry, University of Cambridge , Cambridge CB2 1GA, U.K
| | | | - Paula J Booth
- Department of Chemistry, King's College London , London SE1 1DB, U.K
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31
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Taylor KC, Sanders CR. Regulation of KCNQ/Kv7 family voltage-gated K + channels by lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:586-597. [PMID: 27818172 DOI: 10.1016/j.bbamem.2016.10.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/24/2016] [Accepted: 10/31/2016] [Indexed: 12/19/2022]
Abstract
Many years of studies have established that lipids can impact membrane protein structure and function through bulk membrane effects, by direct but transient annular interactions with the bilayer-exposed surface of protein transmembrane domains, and by specific binding to protein sites. Here, we focus on how phosphatidylinositol 4,5-bisphosphate (PIP2) and polyunsaturated fatty acids (PUFAs) impact ion channel function and how the structural details of the interactions of these lipids with ion channels are beginning to emerge. We focus on the Kv7 (KCNQ) subfamily of voltage-gated K+ channels, which are regulated by both PIP2 and PUFAs and play a variety of important roles in human health and disease. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Keenan C Taylor
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
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32
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Landreh M, Marty MT, Gault J, Robinson CV. A sliding selectivity scale for lipid binding to membrane proteins. Curr Opin Struct Biol 2016; 39:54-60. [PMID: 27155089 PMCID: PMC5287393 DOI: 10.1016/j.sbi.2016.04.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/11/2016] [Accepted: 04/20/2016] [Indexed: 01/24/2023]
Abstract
Biological membranes form barriers that are essential for cellular integrity and compartmentalisation. Proteins in the membrane have co-evolved with their hydrophobic lipid environment, which serves as a solvent for proteins with very diverse requirements. As a result, their interactions range from non-selective to highly discriminating. Mass spectrometry enables us to monitor how lipids interact with membrane proteins and assess their effects on structure and dynamics. Recent studies illustrate the ability to differentiate specific lipid binding, preferential interactions with lipid subsets, and nonselective annular contacts. Here, we consider the biological implications of different lipid-binding scenarios and propose that binding occurs on a sliding selectivity scale, in line with the view of biological membranes as facilitators of dynamic protein and lipid organization.
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Affiliation(s)
- Michael Landreh
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3QZ, United Kingdom
| | - Michael T Marty
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3QZ, United Kingdom
| | - Joseph Gault
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3QZ, United Kingdom
| | - Carol V Robinson
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3QZ, United Kingdom.
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33
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Klein N, Hellmann N, Schneider D. Anionic Lipids Modulate the Activity of the Aquaglyceroporin GlpF. Biophys J 2016; 109:722-31. [PMID: 26287624 DOI: 10.1016/j.bpj.2015.06.063] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 06/11/2015] [Accepted: 06/15/2015] [Indexed: 01/30/2023] Open
Abstract
The structure and composition of a biological membrane can severely influence the activity of membrane-embedded proteins. Here, we show that the E. coli aquaglyceroporin GlpF has only little activity in lipid bilayers formed from native E. coli lipids. Thus, at first glance, GlpF appears to not be optimized for its natural membrane environment. In fact, we found that GlpF activity was severely affected by negatively charged lipids regardless of the exact chemical nature of the lipid headgroup, whereas GlpF was not sensitive to changes in the lateral membrane pressure. These observations illustrate a potential mechanism by which the activity of an α-helical membrane protein is modulated by the negative charge density around the protein.
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Affiliation(s)
- Noreen Klein
- Institut für Pharmazie und Biochemie, Johannes Gutenberg Universität Mainz, Mainz, Germany
| | - Nadja Hellmann
- Institut für Molekulare Biophysik, Johannes Gutenberg Universität Mainz, Mainz, Germany
| | - Dirk Schneider
- Institut für Pharmazie und Biochemie, Johannes Gutenberg Universität Mainz, Mainz, Germany.
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34
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Abstract
Which properties of the membrane environment are essential for the folding and oligomerization of transmembrane proteins? Because the lipids that surround membrane proteins in situ spontaneously organize into bilayers, it may seem intuitive that interactions with the bilayer provide both hydrophobic and topological constraints that help the protein to achieve a stable and functional three-dimensional structure. However, one may wonder whether folding is actually driven by the membrane environment or whether the folded state just reflects an adaptation of integral proteins to the medium in which they function. Also, apart from the overall transmembrane orientation, might the asymmetry inherent in biosynthesis processes cause proteins to fold to out-of-equilibrium, metastable topologies? Which of the features of a bilayer are essential for membrane protein folding, and which are not? To which extent do translocons dictate transmembrane topologies? Recent data show that many membrane proteins fold and oligomerize very efficiently in media that bear little similarity to a membrane, casting doubt on the essentiality of many bilayer constraints. In the following discussion, we argue that some of the features of bilayers may contribute to protein folding, stability and regulation, but they are not required for the basic three-dimensional structure to be achieved. This idea, if correct, would imply that evolution has steered membrane proteins toward an accommodation to biosynthetic pathways and a good fit into their environment, but that their folding is not driven by the latter or dictated by insertion apparatuses. In other words, the three-dimensional structure of membrane proteins is essentially determined by intramolecular interactions and not by bilayer constraints and insertion pathways. Implications are discussed.
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Affiliation(s)
- Jean-Luc Popot
- Centre National de la Recherche Scientifique/Université Paris-7 UMR 7099 , Institut de Biologie Physico-Chimique (FRC 550), 13, rue Pierre-et-Marie-Curie, F-75005 Paris, France
| | - Donald M Engelman
- Department of Molecular Biophysics and Biochemistry, Yale University , Box 208114, New Haven, Connecticut 06520-8114, United States
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35
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Leftin A, Molugu TR, Job C, Beyer K, Brown MF. Area per lipid and cholesterol interactions in membranes from separated local-field (13)C NMR spectroscopy. Biophys J 2015; 107:2274-86. [PMID: 25418296 DOI: 10.1016/j.bpj.2014.07.044] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 06/24/2014] [Accepted: 07/15/2014] [Indexed: 10/24/2022] Open
Abstract
Investigations of lipid membranes using NMR spectroscopy generally require isotopic labeling, often precluding structural studies of complex lipid systems. Solid-state (13)C magic-angle spinning NMR spectroscopy at natural isotopic abundance gives site-specific structural information that can aid in the characterization of complex biomembranes. Using the separated local-field experiment DROSS, we resolved (13)C-(1)H residual dipolar couplings that were interpreted with a statistical mean-torque model. Liquid-disordered and liquid-ordered phases were characterized according to membrane thickness and average cross-sectional area per lipid. Knowledge of such structural parameters is vital for molecular dynamics simulations, and provides information about the balance of forces in membrane lipid bilayers. Experiments were conducted with both phosphatidylcholine (dimyristoylphosphatidylcholine (DMPC) and palmitoyloleoylphosphatidylcholine (POPC)) and egg-yolk sphingomyelin (EYSM) lipids, and allowed us to extract segmental order parameters from the (13)C-(1)H residual dipolar couplings. Order parameters were used to calculate membrane structural quantities, including the area per lipid and bilayer thickness. Relative to POPC, EYSM is more ordered in the ld phase and experiences less structural perturbation upon adding 50% cholesterol to form the lo phase. The loss of configurational entropy is smaller for EYSM than for POPC, thus favoring its interaction with cholesterol in raftlike lipid systems. Our studies show that solid-state (13)C NMR spectroscopy is applicable to investigations of complex lipids and makes it possible to obtain structural parameters for biomembrane systems where isotope labeling may be prohibitive.
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Affiliation(s)
- Avigdor Leftin
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Constantin Job
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Klaus Beyer
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
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36
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Solís-Calero C, Ortega-Castro J, Frau J, Muñoz F. Nonenzymatic Reactions above Phospholipid Surfaces of Biological Membranes: Reactivity of Phospholipids and Their Oxidation Derivatives. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:319505. [PMID: 25977746 PMCID: PMC4419266 DOI: 10.1155/2015/319505] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/24/2015] [Accepted: 03/25/2015] [Indexed: 01/03/2023]
Abstract
Phospholipids play multiple and essential roles in cells, as components of biological membranes. Although phospholipid bilayers provide the supporting matrix and surface for many enzymatic reactions, their inherent reactivity and possible catalytic role have not been highlighted. As other biomolecules, phospholipids are frequent targets of nonenzymatic modifications by reactive substances including oxidants and glycating agents which conduct to the formation of advanced lipoxidation end products (ALEs) and advanced glycation end products (AGEs). There are some theoretical studies about the mechanisms of reactions related to these processes on phosphatidylethanolamine surfaces, which hypothesize that cell membrane phospholipids surface environment could enhance some reactions through a catalyst effect. On the other hand, the phospholipid bilayers are susceptible to oxidative damage by oxidant agents as reactive oxygen species (ROS). Molecular dynamics simulations performed on phospholipid bilayers models, which include modified phospholipids by these reactions and subsequent reactions that conduct to formation of ALEs and AGEs, have revealed changes in the molecular interactions and biophysical properties of these bilayers as consequence of these reactions. Then, more studies are desirable which could correlate the biophysics of modified phospholipids with metabolism in processes such as aging and diseases such as diabetes, atherosclerosis, and Alzheimer's disease.
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Affiliation(s)
- Christian Solís-Calero
- Institut d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
- Instituto de Investigación Sanitaria de Palma, 07010 Palma, Spain
| | - Joaquín Ortega-Castro
- Institut d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
- Instituto de Investigación Sanitaria de Palma, 07010 Palma, Spain
| | - Juan Frau
- Institut d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
- Instituto de Investigación Sanitaria de Palma, 07010 Palma, Spain
| | - Francisco Muñoz
- Institut d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
- Instituto de Investigación Sanitaria de Palma, 07010 Palma, Spain
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37
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Kalli AC, Sansom MSP, Reithmeier RAF. Molecular dynamics simulations of the bacterial UraA H+-uracil symporter in lipid bilayers reveal a closed state and a selective interaction with cardiolipin. PLoS Comput Biol 2015; 11:e1004123. [PMID: 25729859 PMCID: PMC4346270 DOI: 10.1371/journal.pcbi.1004123] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/09/2015] [Indexed: 11/25/2022] Open
Abstract
The Escherichia coli UraA H+-uracil symporter is a member of the nucleobase/ascorbate transporter (NAT) family of proteins, and is responsible for the proton-driven uptake of uracil. Multiscale molecular dynamics simulations of the UraA symporter in phospholipid bilayers consisting of: 1) 1-palmitoyl 2-oleoyl-phosphatidylcholine (POPC); 2) 1-palmitoyl 2-oleoyl-phosphatidylethanolamine (POPE); and 3) a mixture of 75% POPE, 20% 1-palmitoyl 2-oleoyl-phosphatidylglycerol (POPG); and 5% 1-palmitoyl 2-oleoyl-diphosphatidylglycerol/cardiolipin (CL) to mimic the lipid composition of the bacterial inner membrane, were performed using the MARTINI coarse-grained force field to self-assemble lipids around the crystal structure of this membrane transport protein, followed by atomistic simulations. The overall fold of the protein in lipid bilayers remained similar to the crystal structure in detergent on the timescale of our simulations. Simulations were performed in the absence of uracil, and resulted in a closed state of the transporter, due to relative movement of the gate and core domains. Anionic lipids, including POPG and especially CL, were found to associate with UraA, involving interactions between specific basic residues in loop regions and phosphate oxygens of the CL head group. In particular, three CL binding sites were identified on UraA: two in the inner leaflet and a single site in the outer leaflet. Mutation of basic residues in the binding sites resulted in the loss of CL binding in the simulations. CL may play a role as a “proton trap” that channels protons to and from this transporter within CL-enriched areas of the inner bacterial membrane. Symporters are proteins that are responsible for the co-transport of ions and small molecule solutes across cell membranes. UraA is an example of a symporter, and is responsible for the proton-driven uptake of uracil in bacteria like E. coli. Despite its importance as a member of a large family of nucleobase/ascorbate transporters (NAT) and the existence of structural and functional data, the mechanism by which UraA transports uracil across the bacterial membrane, and in particular the role of its diverse and complex lipid environment in the transport mechanism, remains elusive. In this study, we have used a multiscale computational methodology to examine the dynamics of UraA and to elucidate its interactions with lipids that resemble its native environment in the bacterial inner membrane. Our results demonstrate that negatively-charged lipids in the membrane (phosphatidylglycerol and cardiolipin) associate preferentially with UraA and may play a role in its function. Additionally, our simulations resulted in a closed state of UraA, a likely intermediate in the transport mechanism that may not be readily accessible by experimental methods.
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Affiliation(s)
- Antreas C. Kalli
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Mark S. P. Sansom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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38
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Lantez V, Nikolaidis I, Rechenmann M, Vernet T, Noirclerc-Savoye M. Rapid automated detergent screening for the solubilization and purification of membrane proteins and complexes. Eng Life Sci 2015. [DOI: 10.1002/elsc.201400187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Violaine Lantez
- Université Grenoble Alpes, IBS; Grenoble France
- CEA, IBS; Grenoble France
- CNRS, IBS; Grenoble France
| | - Ioulia Nikolaidis
- Université Grenoble Alpes, IBS; Grenoble France
- CEA, IBS; Grenoble France
- CNRS, IBS; Grenoble France
- Department of Biochemistry of Membranes; Bijvoet Center for Biomolecular Research, Utrecht University; The Netherlands
| | - Mathias Rechenmann
- Université Grenoble Alpes, IBS; Grenoble France
- CEA, IBS; Grenoble France
- CNRS, IBS; Grenoble France
| | - Thierry Vernet
- Université Grenoble Alpes, IBS; Grenoble France
- CEA, IBS; Grenoble France
- CNRS, IBS; Grenoble France
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39
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Leman JK, Ulmschneider MB, Gray JJ. Computational modeling of membrane proteins. Proteins 2015; 83:1-24. [PMID: 25355688 PMCID: PMC4270820 DOI: 10.1002/prot.24703] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 10/01/2014] [Accepted: 10/18/2014] [Indexed: 02/06/2023]
Abstract
The determination of membrane protein (MP) structures has always trailed that of soluble proteins due to difficulties in their overexpression, reconstitution into membrane mimetics, and subsequent structure determination. The percentage of MP structures in the protein databank (PDB) has been at a constant 1-2% for the last decade. In contrast, over half of all drugs target MPs, only highlighting how little we understand about drug-specific effects in the human body. To reduce this gap, researchers have attempted to predict structural features of MPs even before the first structure was experimentally elucidated. In this review, we present current computational methods to predict MP structure, starting with secondary structure prediction, prediction of trans-membrane spans, and topology. Even though these methods generate reliable predictions, challenges such as predicting kinks or precise beginnings and ends of secondary structure elements are still waiting to be addressed. We describe recent developments in the prediction of 3D structures of both α-helical MPs as well as β-barrels using comparative modeling techniques, de novo methods, and molecular dynamics (MD) simulations. The increase of MP structures has (1) facilitated comparative modeling due to availability of more and better templates, and (2) improved the statistics for knowledge-based scoring functions. Moreover, de novo methods have benefited from the use of correlated mutations as restraints. Finally, we outline current advances that will likely shape the field in the forthcoming decade.
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Affiliation(s)
- Julia Koehler Leman
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Martin B. Ulmschneider
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jeffrey J. Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
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40
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The safety dance: biophysics of membrane protein folding and misfolding in a cellular context. Q Rev Biophys 2014; 48:1-34. [PMID: 25420508 DOI: 10.1017/s0033583514000110] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Most biological processes require the production and degradation of proteins, a task that weighs heavily on the cell. Mutations that compromise the conformational stability of proteins place both specific and general burdens on cellular protein homeostasis (proteostasis) in ways that contribute to numerous diseases. Efforts to elucidate the chain of molecular events responsible for diseases of protein folding address one of the foremost challenges in biomedical science. However, relatively little is known about the processes by which mutations prompt the misfolding of α-helical membrane proteins, which rely on an intricate network of cellular machinery to acquire and maintain their functional structures within cellular membranes. In this review, we summarize the current understanding of the physical principles that guide membrane protein biogenesis and folding in the context of mammalian cells. Additionally, we explore how pathogenic mutations that influence biogenesis may differ from those that disrupt folding and assembly, as well as how this may relate to disease mechanisms and therapeutic intervention. These perspectives indicate an imperative for the use of information from structural, cellular, and biochemical studies of membrane proteins in the design of novel therapeutics and in personalized medicine.
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41
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Sahu ID, Kroncke BM, Zhang R, Dunagan MM, Smith HJ, Craig A, McCarrick RM, Sanders CR, Lorigan GA. Structural investigation of the transmembrane domain of KCNE1 in proteoliposomes. Biochemistry 2014; 53:6392-401. [PMID: 25234231 PMCID: PMC4196734 DOI: 10.1021/bi500943p] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
KCNE1 is a single-transmembrane protein
of the KCNE family that modulates the function of voltage-gated potassium
channels, including KCNQ1. Hereditary mutations in KCNE1 have been
linked to diseases such as long QT syndrome (LQTS), atrial fibrillation,
sudden infant death syndrome, and deafness. The transmembrane domain
(TMD) of KCNE1 plays a key role in mediating the physical association
with KCNQ1 and in subsequent modulation of channel gating kinetics
and conductance. However, the mechanisms associated with these roles
for the TMD remain poorly understood, highlighting a need for experimental
structural studies. A previous solution NMR study of KCNE1 in LMPG
micelles revealed a curved transmembrane domain, a structural feature
proposed to be critical to KCNE1 function. However, this curvature
potentially reflects an artifact of working in detergent micelles.
Double electron electron resonance (DEER) measurements were conducted
on KCNE1 in LMPG micelles, POPC/POPG proteoliposomes, and POPC/POPG
lipodisq nanoparticles to directly compare the structure of the TMD
in a variety of different membrane environments. Experimentally derived
DEER distances coupled with simulated annealing molecular dynamic
simulations were used to probe the bilayer structure of the TMD of
KCNE1. The results indicate that the structure is helical in proteoliposomes
and is slightly curved, which is consistent with the previously determined
solution NMR structure in micelles. The evident resilience of the
curvature in the KCNE1 TMD leads us to hypothesize that the curvature
is likely to be maintained upon binding of the protein to the KCNQ1
channel.
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Affiliation(s)
- Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
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42
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Differential contribution of tryptophans to the folding and stability of the attachment invasion locus transmembrane β-barrel from Yersinia pestis. Sci Rep 2014; 4:6508. [PMID: 25266561 PMCID: PMC4179465 DOI: 10.1038/srep06508] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 09/15/2014] [Indexed: 11/08/2022] Open
Abstract
Attachment invasion locus (Ail) protein of Yersinia pestis is a crucial outer membrane protein for host invasion and determines bacterial survival within the host. Despite its importance in pathogenicity, surprisingly little is known on Ail biophysical properties. We investigate the contribution of micelle concentrations and interface tryptophans on the Ail β-barrel refolding and unfolding processes. Our results reveal that barrel folding is surprisingly independent of micelle amounts, but proceeds through an on-pathway intermediate that requires the interface W42 for cooperative barrel refolding. On the contrary, the unfolding event is strongly controlled by absolute micelle concentrations. We find that upon Trp → Phe substitution, protein stabilities follow the order W149F>WT>W42F for the refolding, and W42F>WT>W149F for unfolding. W42 confers cooperativity in barrel folding, and W149 clamps the post-folded barrel structure to its micelle environment. Our analyses reveal, for the first time, that interface tryptophan mutation can indeed render greater β-barrel stability. Furthermore, hysteresis in Ail stems from differential barrel-detergent interaction strengths in a micelle concentration-dependent manner, largely mediated by W149. The kinetically stabilized Ail β-barrel has strategically positioned tryptophans to balance efficient refolding and subsequent β-barrel stability, and may be evolutionarily chosen for optimal functioning of Ail during Yersinia pathogenesis.
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Pogozheva ID, Mosberg HI, Lomize AL. Life at the border: adaptation of proteins to anisotropic membrane environment. Protein Sci 2014; 23:1165-96. [PMID: 24947665 DOI: 10.1002/pro.2508] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 12/25/2022]
Abstract
This review discusses main features of transmembrane (TM) proteins which distinguish them from water-soluble proteins and allow their adaptation to the anisotropic membrane environment. We overview the structural limitations on membrane protein architecture, spatial arrangement of proteins in membranes and their intrinsic hydrophobic thickness, co-translational and post-translational folding and insertion into lipid bilayers, topogenesis, high propensity to form oligomers, and large-scale conformational transitions during membrane insertion and transport function. Special attention is paid to the polarity of TM protein surfaces described by profiles of dipolarity/polarizability and hydrogen-bonding capacity parameters that match polarity of the lipid environment. Analysis of distributions of Trp resides on surfaces of TM proteins from different biological membranes indicates that interfacial membrane regions with preferential accumulation of Trp indole rings correspond to the outer part of the lipid acyl chain region-between double bonds and carbonyl groups of lipids. These "midpolar" regions are not always symmetric in proteins from natural membranes. We also examined the hydrophobic effect that drives insertion of proteins into lipid bilayer and different free energy contributions to TM protein stability, including attractive van der Waals forces and hydrogen bonds, side-chain conformational entropy, the hydrophobic mismatch, membrane deformations, and specific protein-lipid binding.
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Affiliation(s)
- Irina D Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, 48109-1065
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Laganowsky A, Reading E, Allison TM, Ulmschneider MB, Degiacomi MT, Baldwin AJ, Robinson CV. Membrane proteins bind lipids selectively to modulate their structure and function. Nature 2014; 510:172-175. [PMID: 24899312 PMCID: PMC4087533 DOI: 10.1038/nature13419] [Citation(s) in RCA: 578] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 04/28/2014] [Indexed: 01/04/2023]
Abstract
Previous studies have established that the folding, structure and function of membrane proteins are influenced by their lipid environments and that lipids can bind to specific sites, for example, in potassium channels. Fundamental questions remain however regarding the extent of membrane protein selectivity towards lipids. Here we report a mass spectrometry approach designed to determine the selectivity of lipid binding to membrane protein complexes. We investigate the mechanosensitive channel of large conductance (MscL) from Mycobacterium tuberculosis and aquaporin Z (AqpZ) and the ammonia channel (AmtB) from Escherichia coli, using ion mobility mass spectrometry (IM-MS), which reports gas-phase collision cross-sections. We demonstrate that folded conformations of membrane protein complexes can exist in the gas phase. By resolving lipid-bound states, we then rank bound lipids on the basis of their ability to resist gas phase unfolding and thereby stabilize membrane protein structure. Lipids bind non-selectively and with high avidity to MscL, all imparting comparable stability; however, the highest-ranking lipid is phosphatidylinositol phosphate, in line with its proposed functional role in mechanosensation. AqpZ is also stabilized by many lipids, with cardiolipin imparting the most significant resistance to unfolding. Subsequently, through functional assays we show that cardiolipin modulates AqpZ function. Similar experiments identify AmtB as being highly selective for phosphatidylglycerol, prompting us to obtain an X-ray structure in this lipid membrane-like environment. The 2.3 Å resolution structure, when compared with others obtained without lipid bound, reveals distinct conformational changes that re-position AmtB residues to interact with the lipid bilayer. Our results demonstrate that resistance to unfolding correlates with specific lipid-binding events, enabling a distinction to be made between lipids that merely bind from those that modulate membrane protein structure and/or function. We anticipate that these findings will be important not only for defining the selectivity of membrane proteins towards lipids, but also for understanding the role of lipids in modulating protein function or drug binding.
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Affiliation(s)
- Arthur Laganowsky
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 5QY, UK
| | - Eamonn Reading
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 5QY, UK
| | - Timothy M. Allison
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 5QY, UK
| | - Martin B. Ulmschneider
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Matteo T. Degiacomi
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 5QY, UK
| | - Andrew J. Baldwin
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 5QY, UK
| | - Carol V. Robinson
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 5QY, UK
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45
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Rouse SL, Marcoux J, Robinson CV, Sansom MSP. Dodecyl maltoside protects membrane proteins in vacuo. Biophys J 2014; 105:648-56. [PMID: 23931313 DOI: 10.1016/j.bpj.2013.06.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 05/14/2013] [Accepted: 06/17/2013] [Indexed: 11/26/2022] Open
Abstract
Molecular dynamics simulations have been used to characterize the effects of transfer from aqueous solution to a vacuum to inform our understanding of mass spectrometry of membrane-protein-detergent complexes. We compared two membrane protein architectures (an α-helical bundle versus a β-barrel) and two different detergent types (phosphocholines versus an alkyl sugar) with respect to protein stability and detergent packing. The β-barrel membrane protein remained stable as a protein-detergent complex in vacuum. Zwitterionic detergents formed conformationally destabilizing interactions with an α-helical membrane protein after detergent micelle inversion driven by dehydration in vacuum. In contrast, a nonionic alkyl sugar detergent resisted micelle inversion, maintaining the solution-phase conformation of the protein. This helps to explain the relative stability of membrane proteins in the presence of alkyl sugar detergents such as dodecyl maltoside.
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Affiliation(s)
- Sarah L Rouse
- Department of Biochemistry, University of Oxford, United Kingdom
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46
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Song Y, Mittendorf KF, Lu Z, Sanders CR. Impact of bilayer lipid composition on the structure and topology of the transmembrane amyloid precursor C99 protein. J Am Chem Soc 2014; 136:4093-6. [PMID: 24564538 PMCID: PMC3985881 DOI: 10.1021/ja4114374] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
C99
(also known as β-CTF) is the 99 residue transmembrane
C-terminal domain (residues 672–770) of the amyloid precursor
protein and is the immediate precursor of the amyloid-β (Aβ)
polypeptides. To test the dependence of the C99 structure on the composition
of the host model membranes, NMR studies of C99 were conducted both
in anionic lyso-myristoylphosphatidylglycerol (LMPG) micelles and
in a series of five zwitterionic bicelle compositions involving phosphatidylcholine
and sphingomyelin in which the acyl chain lengths of these lipid components
varied from 14 to 24 carbons. Some of these mixtures are reported
for the first time in this work and should be of broad utility in
membrane protein research. The site-specific backbone 15N and 1H chemical shifts for C99 in LMPG and in all five
bicelle mixtures were seen to be remarkably similar, indicating little
dependence of the backbone structure of C99 on the composition of
the host model membrane. However, the length of the transmembrane
span was seen to vary in a manner that alters the positioning of the
γ-secretase cleavage sites with respect to the center of the
bilayer. This observation may contribute to the known dependency of
the Aβ42-to-Aβ40 production ratio on both membrane thickness
and the length of the C99 transmembrane domain.
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Affiliation(s)
- Yuanli Song
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine , Nashville, Tennessee 37232-8725, United States
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Cross TA, Ekanayake V, Paulino J, Wright A. Solid state NMR: The essential technology for helical membrane protein structural characterization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 239:100-9. [PMID: 24412099 PMCID: PMC3957465 DOI: 10.1016/j.jmr.2013.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 12/03/2013] [Accepted: 12/09/2013] [Indexed: 05/21/2023]
Abstract
NMR spectroscopy of helical membrane proteins has been very challenging on multiple fronts. The expression and purification of these proteins while maintaining functionality has consumed countless graduate student hours. Sample preparations have depended on whether solution or solid-state NMR spectroscopy was to be performed - neither have been easy. In recent years it has become increasingly apparent that membrane mimic environments influence the structural result. Indeed, in these recent years we have rediscovered that Nobel laureate, Christian Anfinsen, did not say that protein structure was exclusively dictated by the amino acid sequence, but rather by the sequence in a given environment (Anfinsen, 1973) [106]. The environment matters, molecular interactions with the membrane environment are significant and many examples of distorted, non-native membrane protein structures have recently been documented in the literature. However, solid-state NMR structures of helical membrane proteins in proteoliposomes and bilayers are proving to be native structures that permit a high resolution characterization of their functional states. Indeed, solid-state NMR is uniquely able to characterize helical membrane protein structures in lipid environments without detergents. Recent progress in expression, purification, reconstitution, sample preparation and in the solid-state NMR spectroscopy of both oriented samples and magic angle spinning samples has demonstrated that helical membrane protein structures can be achieved in a timely fashion. Indeed, this is a spectacular opportunity for the NMR community to have a major impact on biomedical research through the solid-state NMR spectroscopy of these proteins.
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Affiliation(s)
- Timothy A Cross
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA; Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.
| | - Vindana Ekanayake
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Joana Paulino
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA; Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Anna Wright
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA; Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
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Cross TA, Murray DT, Watts A. Helical membrane protein conformations and their environment. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2013; 42:731-55. [PMID: 23996195 PMCID: PMC3818118 DOI: 10.1007/s00249-013-0925-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 07/25/2013] [Accepted: 08/12/2013] [Indexed: 02/02/2023]
Abstract
Evidence that membrane proteins respond conformationally and functionally to their environment is growing. Structural models, by necessity, have been characterized in preparations where the protein has been removed from its native environment. Different structural methods have used various membrane mimetics that have recently included lipid bilayers as a more native-like environment. Structural tools applied to lipid bilayer-embedded integral proteins are informing us about important generic characteristics of how membrane proteins respond to the lipid environment as compared with their response to other nonlipid environments. Here, we review the current status of the field, with specific reference to observations of some well-studied α-helical membrane proteins, as a starting point to aid the development of possible generic principles for model refinement.
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Affiliation(s)
- Timothy A. Cross
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - Dylan T. Murray
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - Anthony Watts
- Biomembrane structure Unit, Biochemistry Department, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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Klose C, Surma MA, Simons K. Organellar lipidomics—background and perspectives. Curr Opin Cell Biol 2013; 25:406-13. [DOI: 10.1016/j.ceb.2013.03.005] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/21/2013] [Indexed: 11/27/2022]
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50
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Pogozheva ID, Tristram-Nagle S, Mosberg HI, Lomize AL. Structural adaptations of proteins to different biological membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2592-608. [PMID: 23811361 DOI: 10.1016/j.bbamem.2013.06.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 06/04/2013] [Accepted: 06/19/2013] [Indexed: 02/06/2023]
Abstract
To gain insight into adaptations of proteins to their membranes, intrinsic hydrophobic thicknesses, distributions of different chemical groups and profiles of hydrogen-bonding capacities (α and β) and the dipolarity/polarizability parameter (π*) were calculated for lipid-facing surfaces of 460 integral α-helical, β-barrel and peripheral proteins from eight types of biomembranes. For comparison, polarity profiles were also calculated for ten artificial lipid bilayers that have been previously studied by neutron and X-ray scattering. Estimated hydrophobic thicknesses are 30-31Å for proteins from endoplasmic reticulum, thylakoid, and various bacterial plasma membranes, but differ for proteins from outer bacterial, inner mitochondrial and eukaryotic plasma membranes (23.9, 28.6 and 33.5Å, respectively). Protein and lipid polarity parameters abruptly change in the lipid carbonyl zone that matches the calculated hydrophobic boundaries. Maxima of positively charged protein groups correspond to the location of lipid phosphates at 20-22Å distances from the membrane center. Locations of Tyr atoms coincide with hydrophobic boundaries, while distributions maxima of Trp rings are shifted by 3-4Å toward the membrane center. Distributions of Trp atoms indicate the presence of two 5-8Å-wide midpolar regions with intermediate π* values within the hydrocarbon core, whose size and symmetry depend on the lipid composition of membrane leaflets. Midpolar regions are especially asymmetric in outer bacterial membranes and cell membranes of mesophilic but not hyperthermophilic archaebacteria, indicating the larger width of the central nonpolar region in the later case. In artificial lipid bilayers, midpolar regions are observed up to the level of acyl chain double bonds.
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Affiliation(s)
- Irina D Pogozheva
- College of Pharmacy, Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109-1065, USA.
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