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Altered strand transfer activity of a multiple-drug-resistant human immunodeficiency virus type 1 reverse transcriptase mutant with a dipeptide fingers domain insertion.

ABSTRACT: Prolonged highly active anti-retroviral therapy with multiple nucleoside reverse transcriptase inhibitors for the treatment of patients infected with human immunodeficiency virus type 1 (HIV-1) can induce the development of an HIV-1 reverse transcriptase (RT) harboring a dipeptide insertion at the RT fingers domain with a background thymidine analog mutation. This mutation renders viral resistance to multiple nucleoside reverse transcriptase inhibitors. We investigated the effect of the dipeptide fingers domain insertion mutation on strand transfer activity using two clinical RT variants isolated during the pre-treatment and post-treatment of an infected patient, termed pre-drug RT without dipeptide insertion and post-drug RT with Ser-Gly insertion, respectively. First, the post-drug RT displayed elevated strand transfer activity compared to the pre-drug RT, with two different RNA templates. Second, the post-drug RT exhibited less RNA template degradation than the pre-drug RT but higher polymerization-dependent RNase H activity. Third, the post-drug RT had a faster association rate (k(on)) for template binding and a lower equilibrium binding constant K(d) for the template, leading to a template binding affinity tighter than that of the pre-drug RT. The k(off) values for the pre-drug RT and the post-drug RT were similar. Finally, the removal of the dipeptide insertion from the post-drug RT abolished the elevated strand transfer activity and RNase H activity, in addition to the loss of azidothymidine resistance. These biochemical data suggest that the dipeptide insertion elevates strand transfer activity by increasing the interaction of the RT with the RNA donor template, promoting cleavage that generates more invasion sites for the acceptor template during DNA synthesis.

SUBMITTER: Nguyen LA

PROVIDER: S-EPMC3770445 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Altered strand transfer activity of a multiple-drug-resistant human immunodeficiency virus type 1 reverse transcriptase mutant with a dipeptide fingers domain insertion.

Nguyen Laura A LA Daddacha Waaqo W Rigby Sean S Bambara Robert A RA Kim Baek B

Journal of molecular biology 20111112 2

Prolonged highly active anti-retroviral therapy with multiple nucleoside reverse transcriptase inhibitors for the treatment of patients infected with human immunodeficiency virus type 1 (HIV-1) can induce the development of an HIV-1 reverse transcriptase (RT) harboring a dipeptide insertion at the RT fingers domain with a background thymidine analog mutation. This mutation renders viral resistance to multiple nucleoside reverse transcriptase inhibitors. We investigated the effect of the dipeptid ...[more]

PMID: 22100453

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Project description:Site-directed photoaffinity cross-linking experiments were performed by using human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) mutants with unique cysteine residues at several positions (i.e., positions 65, 67, 70, and 74) in the fingers subdomain of the p66 subunit. Since neither the introduction of the unique cysteine residues into the fingers nor the modification of the SH groups of these residues with photoaffinity cross-linking reagents caused a significant decrease in the enzymatic activities of RT, we were able to use this system to measure distances between specific positions in the fingers domain of RT and double-stranded DNA. HIV-1 RT is quite flexible. There are conformational changes associated with binding of the normal substrates and nonnucleoside RT inhibitors (NNRTIs). Cross-linking was used to monitor intramolecular movements associated with binding of an NNRTI either in the presence or in the absence of an incoming deoxynucleoside triphosphate (dNTP). Binding an incoming dNTP at the polymerase active site decreased the efficiency of cross-linking but caused only modest changes in the preferred positions of cross-linking. This finding suggests that the fingers of p66 are closer to an extended template in the "open" configuration of the enzyme with the fingers away from the active site than in the closed configuration with the fingers in direct contact with the incoming dNTP. NNRTI binding caused increased cross-linking in experiments with diazirine reagents (especially with a diazirine reagent with a longer linker) and a moderate shift in the preferred sites of interaction with the template. Cross-linking occurred closer to the polymerase active site for RTs modified at positions 70 and 74. The effects of NNRTI binding were more pronounced in the absence of a bound dNTP; pretreatment of HIV-1 RT with an NNRTI reduced the effect of dNTP binding. These observations can be explained if the binding of NNRTI causes a decrease in the flexibility in the fingers subdomain of RT-NNRTI complex and a decrease in the distance from the fingers to the template extension.

Project description:In the SAILING study, dolutegravir demonstrated superior virologic efficacy compared with raltegravir in treatment-experienced, integrase strand transfer inhibitor (INSTI)-naive patients with HIV-1 who harbored resistance to ?2 antiretroviral drug classes. Significantly fewer dolutegravir-treated patients demonstrated virologic failure with treatment-emergent resistance than raltegravir-treated patients through 48 weeks. Investigator-selected background therapy (ISBT) included at least one fully active agent, selected on the basis of resistance analysis. Genotypic and phenotypic resistance testing were performed on baseline and time-of-failure samples from patients with protocol-defined virologic failure (PDVF). A post hoc analysis of SAILING (N?=?715; 354 dolutegravir, 361 raltegravir) assessed efficacy in subpopulations defined by ISBT activity, resistance profiles, and treatment history. When ISBT contained only nucleoside reverse transcriptase inhibitors (NRTIs), PDVF occurred in 0% (0/32) of dolutegravir-treated patients and 21.9% (7/32) of raltegravir-treated patients (p?=?.005). In patients harboring M184?V whose ISBT contained lamivudine or emtricitabine plus a second NRTI, 0% (0/13) of dolutegravir- and 33.3% (4/12) of raltegravir-treated patients (p?=?.026) experienced PDVF. Among patients receiving protease inhibitor (PI)-containing ISBT, 6.0% (18/300) of dolutegravir-treated patients versus 11.8% (36/305) of raltegravir-treated patients (p?=?.012) experienced PDVF. Darunavir/ritonavir was part of ISBT in 130 dolutegravir-treated patients and 145 raltegravir-treated patients; 6 (4.6%) and 12 (8.3%), respectively, experienced PDVF (difference -3.7%; 95% confidence interval: -10.1% to 2.5%; p?=?.256). There was no or less virologic failure in treatment-experienced, INSTI-naive subjects receiving dolutegravir versus raltegravir, even when the ISBT was suboptimal or NRTI resistance was present at baseline. These findings are not explained by the use of PI/ritonavir-containing ISBT.

Dataset Information

Altered strand transfer activity of a multiple-drug-resistant human immunodeficiency virus type 1 reverse transcriptase mutant with a dipeptide fingers domain insertion.

Publications

Altered strand transfer activity of a multiple-drug-resistant human immunodeficiency virus type 1 reverse transcriptase mutant with a dipeptide fingers domain insertion.

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