title: Characterization of HIV-1 resistance to a fusion inhibitor, N36, derived from the gp41 amino-terminal heptad repeat.
abstract: A transmembrane glycoprotein of HIV-1, gp41, plays a central role in membrane fusion of HIV-1 and host cells. Peptides derived from the amino- and carboxyl-terminal heptad repeat (N-HR and C-HR, respectively) of gp41 inhibit this fusion. The mechanism of resistance to enfuvirtide, a C-HR-derived peptide, is well defined; however the mechanism of resistance to N-HR-derived peptides remains unclear. We characterized an HIV-1 isolate resistant to the N-HR-derived peptide, N36. This HIV-1 acquired a total of four amino acid substitutions, D36G, N126K and E137Q in gp41, and P183Q in gp120. Among these substitutions, N126K and/or E137Q conferred resistance to not only N36, but also C34, which is the corresponding C-HR-derived peptide fusion inhibitor. We performed crystallographic and biochemical analysis of the 6-helix bundle formed by synthetic gp41-derived peptides containing the N126K/E137Q substitutions. The structure of the 6-helix bundle with N126K/E137Q was identical to that in wild-type HIV-1 except for the presence of a new hydrogen bond. Denaturing experiments revealed that the stability of the 6-helix bundle of N126K/E137Q is greater than in the wild-type. These results suggest that the stabilizing effect of N126K/E137Q provides resistance to N36 and C34.
authors.affiliation: Laboratory of Virus Control, Institute for Virus Research, Kyoto University, 53 Kawaramachi Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Izumi
authors.forename: Shota
authors.initials: S
authors.lastname: Nakamura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakano
authors.forename: Kazuya
authors.initials: K
authors.lastname: Shimura
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Sakagami
authors.forename: Shinya
authors.initials: S
authors.lastname: Oishi
authors.forename: Susumu
authors.initials: S
authors.lastname: Uchiyama
authors.forename: Tadayasu
authors.initials: T
authors.lastname: Ohkubo
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Fujii
authors.forename: Masao
authors.initials: M
authors.lastname: Matsuoka
authors.forename: Eiichi N
authors.initials: EN
authors.lastname: Kodama
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D019380:Anti-HIV Agents / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D024882:Drug Resistance, Viral; D015700:HIV Envelope Protein gp41 / Q000494:pharmacology*; D015497:HIV-1 / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics; D020125:Mutation, Missense; D010446:Peptide Fragments / Q000494:pharmacology*; D011489:Protein Denaturation; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D019380:Anti-HIV Agents; D015700:HIV Envelope Protein gp41; D010446:Peptide Fragments; C407149:peptide C34; C407148:peptide N36