title: Retrocyclin RC-101 overcomes cationic mutations on the heptad repeat 2 region of HIV-1 gp41.
abstract: Retrocyclin RC-101, a theta-defensin with lectin-like properties, potently inhibits infection by many HIV-1 subtypes by binding to the heptad repeat 2 (HR2) region of glycoprotein 41 (gp41) and preventing six-helix bundle formation. In the present study, we used in silico computational exploration to identify residues of HR2 that interacted with RC-101, and then analyzed the HIV-1 sequence database at Los Alamos National Laboratory (New Mexico, USA) for residue variations in the heptad repeat 1 (HR1) and HR2 segments that could plausibly impart in vivo resistance. Docking RC-101 to gp41 peptides in silico confirmed its strong preference for HR2 over HR1, and implicated residues crucial for its ability to bind HR2. We mutagenized these residues in pseudotyped HIV-1 JR.FL reporter viruses, and subjected them to single-round replication assays in the presence of 1.25-10 microg x mL(-1) RC-101. Apart from one mutant that was partially resistant to RC-101, the other pseudotyped viruses with single-site cationic mutations in HR2 manifested absent or impaired infectivity or retained wild-type susceptibility to RC-101. Overall, these data suggest that most mutations capable of rendering HIV-1 resistant to RC-101 will also exert deleterious effects on the ability of HIV-1 to initiate infections - an interesting and novel property for a potential topical microbicide.
authors.affiliation: Molecular Biology & Microbiology, Biomolecular Science Center, Burnett College of Biomedical Sciences at University of Central Florida, Orlando, FL 32816, USA.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Fuhrman
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Warren
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Waring
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Dutz
authors.forename: Shantanu
authors.initials: S
authors.lastname: Sharma
authors.forename: Robert I
authors.initials: RI
authors.lastname: Lehrer
authors.forename: Amy L
authors.initials: AL
authors.lastname: Cole
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Cole
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D019295:Computational Biology / Q000379:methods; D023082:Defensins / Q000378:metabolism* / Q000494:pharmacology; D024882:Drug Resistance, Viral / Q000235:genetics; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014779:Virus Replication / Q000187:drug effects
chemical_list: D023082:Defensins; D015700:HIV Envelope Protein gp41; D010455:Peptides; C450143:RC 101; C450142:theta-defensin