scholarly journals Self-assembly of polymer-encased lipid nanodiscs and membrane protein reconstitution

2018 ◽  
Author(s):  
Bikash R. Sahoo ◽  
Takuya Genjo ◽  
Kanhu C. Moharana ◽  
Ayyalusamy Ramamoorthy
Keyword(s):  
Membrane Proteins ◽  
Self Assembly ◽  
Md Simulation ◽  
Mechanistic Model ◽  
Coarse Graining ◽  
Spatial Arrangement ◽  
Molar Ratio ◽  
Dynamics And Function ◽  
And Function ◽  
Lipid Nanodiscs

AbstractThe absence of detergent and curvature makes nanodiscs to be excellent membrane mimetics. The lack of structural and mechanistic model of polymer-encapsulated lipid-nanodiscs limits their use to study the structure, dynamics and function of membrane proteins. In this study, we parametrized and optimized the coarse-graining (CG) bead-mapping for two differently charged and functionalized copolymers, namely styrene-maleic acid (SMAEA) and polymethacrylate (PMAQA), for the Martini force-field framework and showed nanodisc formation (< 8 nm diameter) on a time scale of tens of microseconds using molecular dynamics (MD) simulation. Structural models of ~ 2.0 or 4.8 kDa PMAQA and ~2.2 kDa SMAEA polymer based lipid-nanodiscs highlights the importance of polymer chemical structure, size and polymer:lipid molar ratio in the optimization of nanodisc structure. The ideal spatial arrangement of polymers in nanodisc, nanodisc size and thermal stability obtained from our MD simulation correlates well with the experimental observations. The polymer-nanodisc were tested for the reconstitution of single-pass or multi-pass transmembrane proteins. We expect this study to be useful in the development of novel polymer based lipid-nanodiscs and for the structural studies of membrane proteins.TOC GRAPHICS

scholarly journals Lipid Membrane Mimetics in Functional and Structural Studies of Integral Membrane Proteins

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 685
Author(s):  
Saman Majeed ◽  
Akram Bani Ahmad ◽  
Ujala Sehar ◽  
Elka R. Georgieva
Keyword(s):  
Membrane Proteins ◽  
Lipid Membrane ◽  
Physiological State ◽  
Integral Membrane Proteins ◽  
Membrane Properties ◽  
Protein Activity ◽  
Functional Studies ◽  
Dynamics And Function ◽  
And Function

Integral membrane proteins (IMPs) fulfill important physiological functions by providing cell–environment, cell–cell and virus–host communication; nutrients intake; export of toxic compounds out of cells; and more. However, some IMPs have obliterated functions due to polypeptide mutations, modifications in membrane properties and/or other environmental factors—resulting in damaged binding to ligands and the adoption of non-physiological conformations that prevent the protein from returning to its physiological state. Thus, elucidating IMPs’ mechanisms of function and malfunction at the molecular level is important for enhancing our understanding of cell and organism physiology. This understanding also helps pharmaceutical developments for restoring or inhibiting protein activity. To this end, in vitro studies provide invaluable information about IMPs’ structure and the relation between structural dynamics and function. Typically, these studies are conducted on transferred from native membranes to membrane-mimicking nano-platforms (membrane mimetics) purified IMPs. Here, we review the most widely used membrane mimetics in structural and functional studies of IMPs. These membrane mimetics are detergents, liposomes, bicelles, nanodiscs/Lipodisqs, amphipols, and lipidic cubic phases. We also discuss the protocols for IMPs reconstitution in membrane mimetics as well as the applicability of these membrane mimetic-IMP complexes in studies via a variety of biochemical, biophysical, and structural biology techniques.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

How Do Lipids Affect the Structure and Function of Integral Membrane Proteins

2012 ◽  
Vol 28 (11) ◽  
pp. 866
Author(s):  
Jie HENG ◽  
Yan WU ◽  
Xianping WANG ◽  
Kai ZHANG
Keyword(s):  
Membrane Proteins ◽  
Structure And Function ◽  
Integral Membrane Proteins ◽  
And Function

Structure prediction of SPAK C-terminal domain and analysis of its binding to RFXV/I motifs by homology modelling, docking, and molecular dynamics simulation studies

2020 ◽  
Vol 16 ◽  
Author(s):  
Mubarak A. Alamri ◽  
Ahmed D. Alafnan ◽  
Obaid Afzal ◽  
Alhumaidi B. Alabbas ◽  
Safar M. Alqahtani
Keyword(s):  
Molecular Dynamic ◽  
Dynamic Stability ◽  
Md Simulation ◽  
Homology Modelling ◽  
Antihypertensive Agents ◽  
Structure And Function ◽  
Dynamics Simulation ◽  
Dimensional Structure ◽  
Terminal Domain ◽  
And Function

Background: The STE20/SPS1-related proline/alanine-rich kinase (SPAK) is a component of WNKSPAK/OSR1 signaling pathway that plays an essential role in blood pressure regulation. The function of SPAK is mediated by its highly conserved C-terminal domain (CTD) that interacts with RFXV/I motifs of upstream activators, WNK kinases, and downstream substrate, cation-chloride cotransporters. Objective: To determine and validate the three-dimensional structure of the CTD of SPAK and to study and analyze its interaction with the RFXV/I motifs. Methods: A homology model of SPAK CTD was generated and validated through multiple approaches. The model was based on utilizing the OSR1 protein kinase as a template. This model was subjected to 100 ns molecular dynamic (MD) simulation to evaluate its dynamic stability. The final equilibrated model was used to dock the RFQV-peptide derived from WNK4 into the primary pocket that was determined based on the homology sequence between human SPAK and OSR1 CTDs. The mechanism of interaction, conformational rearrangement and dynamic stability of the binding of RFQV-peptide to SPAK CTD were characterized by molecular docking and molecular dynamic simulation. Results: The MD simulation suggested that the binding of RFQV induces a large conformational change due to the distribution of salt bridge within the loop regions. These results may help in understanding the relation between the structure and function of SPAK CTD and to support drug design of potential SPAK kinase inhibitors as antihypertensive agents. Conclusion: This study provides deep insight into SPAK CTD structure and function relationship.

Simulation studies of the interactions between membrane proteins and detergents

2005 ◽  
Vol 33 (5) ◽  
pp. 910-912 ◽  
Author(s):  
P.J. Bond ◽  
J. Cuthbertson ◽  
M.S.P. Sansom
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Self Assembly ◽  
Kinetic Mechanism ◽  
Coarse Grained ◽  
Simulation Studies ◽  
High Resolution Data ◽  
Biologically Relevant ◽  
Structure And Dynamics ◽  
Detergent Interactions

Interactions between membrane proteins and detergents are important in biophysical and structural studies and are also biologically relevant in the context of folding and transport. Despite a paucity of high-resolution data on protein–detergent interactions, novel methods and increased computational power enable simulations to provide a means of understanding such interactions in detail. Simulations have been used to compare the effect of lipid or detergent on the structure and dynamics of membrane proteins. Moreover, some of the longest and most complex simulations to date have been used to observe the spontaneous formation of membrane protein–detergent micelles. Common mechanistic steps in the micelle self-assembly process were identified for both α-helical and β-barrel membrane proteins, and a simple kinetic mechanism was proposed. Recently, simplified (i.e. coarse-grained) models have been utilized to follow long timescale transitions in membrane protein–detergent assemblies.

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