title: Amino acid 36 in the human immunodeficiency virus type 1 gp41 ectodomain controls fusogenic activity: implications for the molecular mechanism of viral escape from a fusion inhibitor.
abstract: We have previously described a human immunodeficiency virus type 1 (HIV-1) proviral clone, pL2, derived from defective viral particles with higher fusogenicity than the prototypic NL4-3 virus. In this study, we attempted to determine the region that confers the enhanced fusion activity by creating envelope recombinants between pL2 and pNL4-3, as well as point mutants based on pNL4-3. The results indicate that amino acid 36 of gp41 is key for the fusogenic activity and infectivity enhancement and that glycine 36 (36G) of gp41 in pL2 is conserved in nearly all HIV-1 isolates except for pNL4-3. The mutation 36G-->D in a primary-isolate-derived Env decreased syncytium-forming activity and infectivity. The assays for cell-cell fusion and viral binding suggested that the enhanced fusion mediated by the 36D-->G mutation is not due to increased binding efficiency but is directly due to actual enhancement of viral fusion activity. Interestingly, this amino acid position is exactly equivalent to that at which the mutation of HIV-1 isolates that have escaped from a fusion inhibitor, enfuvirtide (T-20), has been frequently observed. The correlation between these previous findings and our findings was suggested by structural analysis. Our finding, therefore, has implications for a molecular basis of the viral escape from this drug.
authors.affiliation: Department of Pathology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kinomoto
authors.forename: Masaru
authors.initials: M
authors.lastname: Yokoyama
authors.forename: Hironori
authors.initials: H
authors.lastname: Sato
authors.forename: Asato
authors.initials: A
authors.lastname: Kojima
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kurata
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ikuta
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Sata
authors.forename: Kenzo
authors.initials: K
authors.lastname: Tokunaga
mesh_terms: D000596:Amino Acids / Q000235:genetics; D002459:Cell Fusion; D002460:Cell Line; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000235:genetics*; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008958:Models, Molecular; D017354:Point Mutation; D014779:Virus Replication
chemical_list: D000596:Amino Acids; D015700:HIV Envelope Protein gp41