Download MendeleyStructural and functional analysis of the HIV gp41 core containing an Ile573 to Thr substitution: implications for membrane fusion.
Liu, J., Shu, W., Fagan, M.B., Nunberg, J.H., Lu, M.(2001) Biochemistry 40: 2797-2807
- PubMed: 11258890
- DOI: https://doi.org/10.1021/bi0024759
- Primary Citation of Related Structures:
1F23 - PubMed Abstract:
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.
Organizational Affiliation:
Department of Biochemistry, Weill Medical College of Cornell University, New York, New York 10021, USA.
