title: The M-T hook structure is critical for design of HIV-1 fusion inhibitors.
abstract: CP621-652 is a potent HIV-1 fusion inhibitor peptide derived from the C-terminal heptad repeat of gp41. We recently identified that its N-terminal residues Met-626 and Thr-627 adopt a unique hook-like structure (termed M-T hook) thus stabilizing the interaction of the inhibitor with the deep pocket on the N-terminal heptad repeat. In this study, we further demonstrated that the M-T hook structure is a key determinant of CP621-652 in terms of its thermostability and anti-HIV activity. To directly define the structure and function of the M-T hook, we generated the peptide MT-C34 by incorporating Met-626 and Thr-627 into the N terminus of the C-terminal heptad repeat-derived peptide C34. The high resolution crystal structure (1.9 Å) of MT-C34 complexed by an N-terminal heptad repeat-derived peptide reveals that the M-T hook conformation is well preserved at the N-terminal extreme of the inhibitor. Strikingly, addition of two hook residues could dramatically enhance the binding affinity and thermostability of 6-helix bundle core. Compared with C34, MT-C34 exhibited significantly increased activity to inhibit HIV-1 envelope-mediated cell fusion (6.6-fold), virus entry (4.5-fold), and replication (6-fold). Mechanistically, MT-C34 had a 10.5-fold higher increase than C34 in blocking 6-helix bundle formation. We further showed that MT-C34 possessed higher potency against T20 (Enfuvirtide, Fuzeon)-resistant HIV-1 variants. Therefore, this study provides convincing data for our proposed concept that the M-T hook structure is critical for designing HIV-1 fusion inhibitors.
authors.affiliation: MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, 9 Dong Dan San Tiao, Beijing 100730, China.
authors.forename: Huihui
authors.initials: H
authors.lastname: Chong
authors.forename: Xue
authors.initials: X
authors.lastname: Yao
authors.forename: Jianping
authors.initials: J
authors.lastname: Sun
authors.forename: Zonglin
authors.initials: Z
authors.lastname: Qiu
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.forename: Sandro
authors.initials: S
authors.lastname: Waltersperger
authors.forename: Meitian
authors.initials: M
authors.lastname: Wang
authors.forename: Sheng
authors.initials: S
authors.lastname: Cui
authors.forename: Yuxian
authors.initials: Y
authors.lastname: He
mesh_terms: D002460:Cell Line; D018360:Crystallography, X-Ray; D015195:Drug Design; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000378:metabolism; D023581:HIV Fusion Inhibitors / Q000737:chemistry / Q000494:pharmacology; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D055550:Protein Stability; D017433:Protein Structure, Secondary; D053586:Virus Internalization / Q000187:drug effects*; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D015700:HIV Envelope Protein gp41; D023581:HIV Fusion Inhibitors; D010455:Peptides; C514787:gp41 protein, Human immunodeficiency virus 1