title: Structural characterization of B and non-B subtypes of HIV-protease: insights into the natural susceptibility to drug resistance development.
abstract: Although a majority of HIV-1 infections in Brazil are caused by the subtype B virus (also prevalent in the United States and Western Europe), viral subtypes F and C are also found very frequently. Genomic differences between the subtypes give rise to sequence variations in the encoded proteins, including the HIV-1 protease. The current anti-HIV drugs have been developed primarily against subtype B and the effects arising from the combination of drug-resistance mutations with the naturally existing polymorphisms in non-B HIV-1 subtypes are only beginning to be elucidated. To gain more insights into the structure and function of different variants of HIV proteases, we have determined a 2.1 A structure of the native subtype F HIV-1 protease (PR) in complex with the protease inhibitor TL-3. We have also solved crystal structures of two multi-drug resistant mutant HIV PRs in complex with TL-3, from subtype B (Bmut) carrying the primary mutations V82A and L90M, and from subtype F (Fmut) carrying the primary mutation V82A plus the secondary mutation M36I, at 1.75 A and 2.8 A resolution, respectively. The proteases Bmut, Fwt and Fmut exhibit sevenfold, threefold, and 54-fold resistance to TL-3, respectively. In addition, the structure of subtype B wild type HIV-PR in complex with TL-3 has been redetermined in space group P6(1), consistent with the other three structures. Our results show that the primary mutation V82A causes the known effect of collapsing the S1/S1' pockets that ultimately lead to the reduced inhibitory effect of TL-3. Our results further indicate that two naturally occurring polymorphic substitutions in subtype F and other non-B HIV proteases, M36I and L89M, may lead to early development of drug resistance in patients infected with non-B HIV subtypes.
authors.affiliation: Grupo de Cristalografia, Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador Saocarlense, 400, CEP 13560-970, São Carlos, SP, Brazil.
authors.forename: Mario
authors.initials: M
authors.lastname: Sanches
authors.forename: Sandra
authors.initials: S
authors.lastname: Krauchenco
authors.forename: Nadia H
authors.initials: NH
authors.lastname: Martins
authors.forename: Alla
authors.initials: A
authors.lastname: Gustchina
authors.forename: Alexander
authors.initials: A
authors.lastname: Wlodawer
authors.forename: Igor
authors.initials: I
authors.lastname: Polikarpov
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D024882:Drug Resistance, Viral; D016333:HIV Protease / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017320:HIV Protease Inhibitors / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011110:Polymorphism, Genetic; D016415:Sequence Alignment
chemical_list: D017320:HIV Protease Inhibitors; D007527:Isoenzymes; D016333:HIV Protease