Structural highlights
Function
[GAG_MLVAV] Gag polyprotein plays a role in budding and is processed by the viral protease during virion maturation outside the cell. During budding, it recruits, in a PPXY-dependent or independent manner, Nedd4-like ubiquitin ligases that conjugate ubiquitin molecules to Gag, or to Gag binding host factors. Interaction with HECT ubiquitin ligases probably link the viral protein to the host ESCRT pathway and facilitate release (By similarity). Matrix protein p15 targets Gag and gag-pol polyproteins to the plasma membrane via a multipartite membrane binding signal, that includes its myristoylated N-terminus. Also mediates nuclear localization of the preintegration complex (By similarity). Nucleocapsid protein p10 is involved in the packaging and encapsidation of two copies of the genome. Binds with high affinity to conserved UCUG elements within the packaging signal, located near the 5'-end of the genome. This binding is dependent on genome dimerization (By similarity).
Publication Abstract from PubMed
After entry into target cells, retroviruses encounter the host restriction factors such as Fv1 and TRIM5alpha. While it is clear that these factors target retrovirus capsid proteins (CA), recognition remains poorly defined in the absence of structural information. To better understand the binding interaction between TRIM5alpha and CA, we selected a panel of novel N-tropic murine leukaemia virus (N-MLV) escape mutants by a serial passage of replication competent N-MLV in rhesus macaque TRIM5alpha (rhTRIM5alpha)-positive cells using a small percentage of unrestricted cells to allow multiple rounds of virus replication. The newly identified mutations, many of which involve changes in charge, are distributed over the outer 'top' surface of N-MLV CA, including the N-terminal beta-hairpin, and map up to 29 A(o) apart. Biological characterisation with a number of restriction factors revealed that only one of the new mutations affects restriction by human TRIM5alpha, indicating significant differences in the binding interaction between N-MLV and the two TRIM5alphas, whereas three of the mutations result in dual sensitivity to Fv1(n) and Fv1(b). Structural studies of two mutants show that no major changes in the overall CA conformation are associated with escape from restriction. We conclude that interactions involving much, if not all, of the surface of CA are vital for TRIM5alpha binding.
Novel escape mutants suggest an extensive TRIM5alpha binding site spanning the entire outer surface of the murine leukemia virus capsid protein.,Ohkura S, Goldstone DC, Yap MW, Holden-Dye K, Taylor IA, Stoye JP PLoS Pathog. 2011 Mar;7(3):e1002011. Epub 2011 Mar 31. PMID:21483490[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Ohkura S, Goldstone DC, Yap MW, Holden-Dye K, Taylor IA, Stoye JP. Novel escape mutants suggest an extensive TRIM5alpha binding site spanning the entire outer surface of the murine leukemia virus capsid protein. PLoS Pathog. 2011 Mar;7(3):e1002011. Epub 2011 Mar 31. PMID:21483490 doi:10.1371/journal.ppat.1002011
