[Q89797_9HIV1] The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity).[SAAS:SAAS000328_004_020447][RuleBase:RU004292] The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity).[SAAS:SAAS000328_004_240990]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The envelope glycoprotein of HIV-1 consists of the surface subunit gp120 and the transmembrane subunit gp41. Binding of gp120 to target cell receptors induces a conformational change in gp41, which then mediates the fusion of viral and cellular membranes. A buried isoleucine (Ile573) in a central trimeric coiled coil within the fusion-active gp41 ectodomain core is thought to favor this conformational activation. The role of Ile573 in determining the structure and function of the gp120-gp41 complex was investigated by mutating this residue to threonine, a nonconservative substitution in HIV-1 that occurs naturally in SIV. While the introduction of Thr573 markedly destabilized the gp41 core, the three-dimensional structure of the mutant trimer of hairpins was very similar to that of the wild-type molecule. A new hydrogen-bonding interaction between the buried Thr573 and Thr569 residues appears to allow formation of the trimer-of-hairpins structure at physiological temperature. The mutant envelope glycoprotein expressed in 293T cells and incorporated within pseudotyped virions displayed only a moderate reduction in syncytium-inducing capacity and virus infectivity, respectively. Our results demonstrate that the proper folding of the gp41 core underlies the membrane fusion properties of the gp120-gp41 complex. An understanding of the gp41 activation process may suggest novel strategies for vaccine and antiviral drug development.
Structural and functional analysis of the HIV gp41 core containing an Ile573 to Thr substitution: implications for membrane fusion.,Liu J, Shu W, Fagan MB, Nunberg JH, Lu M Biochemistry. 2001 Mar 6;40(9):2797-807. PMID:11258890[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑Liu J, Shu W, Fagan MB, Nunberg JH, Lu M. Structural and functional analysis of the HIV gp41 core containing an Ile573 to Thr substitution: implications for membrane fusion. Biochemistry. 2001 Mar 6;40(9):2797-807. PMID:11258890
