5kzb
From Proteopedia
Crystal structure of the Rous sarcoma virus matrix protein (aa 2-102). Space group I4122
Structural highlights
FunctionPOL_RSVP Capsid protein p27 forms the spherical core of the virus that encapsulates the genomic RNA-nucleocapsid complex (By similarity). The aspartyl protease mediates proteolytic cleavages of Gag and Gag-Pol polyproteins during or shortly after the release of the virion from the plasma membrane. Cleavages take place as an ordered, step-wise cascade to yield mature proteins. This process is called maturation. Displays maximal activity during the budding process just prior to particle release from the cell (By similarity). Publication Abstract from PubMedBinding of the retroviral structural protein Gag to the cellular plasma membrane is mediated by the protein's matrix (MA) domain. Prominent among MA-PM interactions is electrostatic attraction between the positively charged MA domain and the negatively charged plasma membrane inner leaflet. Previously, we reported that membrane association of HIV-1 Gag, as well as purified Rous sarcoma virus (RSV) MA and Gag, depends strongly on the presence of acidic lipids and is enhanced by cholesterol (Chol). The mechanism underlying this enhancement was unclear. Here, using a broad set of in vitro and in silico techniques we addressed molecular mechanisms of association between RSV MA and model membranes, and investigated how Chol enhances this association. In neutron scattering experiments with liposomes in the presence or absence of Chol, MA preferentially interacted with preexisting POPS-rich clusters formed by nonideal lipid mixing, binding peripherally to the lipid headgroups with minimal perturbation to the bilayer structure. Molecular dynamics simulations showed a stronger MA-bilayer interaction in the presence of Chol, and a large Chol-driven increase in lipid packing and membrane surface charge density. Although in vitro MA-liposome association is influenced by disparate variables, including ionic strength and concentrations of Chol and charged lipids, continuum electrostatic theory revealed an underlying dependence on membrane surface potential. Together, these results conclusively show that Chol affects RSV MA-membrane association by making the electrostatic potential at the membrane surface more negative, while decreasing the penalty for lipid headgroup desolvation. The presented approach can be applied to other viral and nonviral proteins. Cholesterol Promotes Protein Binding by Affecting Membrane Electrostatics and Solvation Properties.,Doktorova M, Heberle FA, Kingston RL, Khelashvili G, Cuendet MA, Wen Y, Katsaras J, Feigenson GW, Vogt VM, Dick RA Biophys J. 2017 Nov 7;113(9):2004-2015. doi: 10.1016/j.bpj.2017.08.055. PMID:29117524[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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