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Biochemical analysis of the role of G118R-linked dolutegravir drug resistance substitutions in HIV-1 integrase.

ABSTRACT: Drug resistance mutations (DRMs) have been reported for all currently approved anti-HIV drugs, including the latest integrase strand transfer inhibitors (INSTIs). We previously used the new INSTI dolutegravir (DTG) to select a G118R integrase resistance substitution in tissue culture and also showed that secondary substitutions emerged at positions H51Y and E138K. Now, we have characterized the impact of the G118R substitution, alone or in combination with either H51Y or E138K, on 3' processing and integrase strand transfer activity. The results show that G118R primarily impacted the strand transfer step of integration by diminishing the ability of integrase-long terminal repeat (LTR) complexes to bind target DNA. The addition of H51Y and E138K to G118R partially restored strand transfer activity by modulating the formation of integrase-LTR complexes through increasing LTR DNA affinity and total DNA binding, respectively. This unique mechanism, in which one function of HIV integrase partially compensates for the defect in another function, has not been previously reported. The G118R substitution resulted in low-level resistance to DTG, raltegravir (RAL), and elvitegravir (EVG). The addition of either of H51Y or E138K to G118R did not enhance resistance to DTG, RAL, or EVG. Homology modeling provided insight into the mechanism of resistance conferred by G118R as well as the effects of H51Y or E138K on enzyme activity. The G118R substitution therefore represents a potential avenue for resistance to DTG, similar to that previously described for the R263K substitution. For both pathways, secondary substitutions can lead to either diminished integrase activity and/or increased INSTI susceptibility.

SUBMITTER: Quashie PK

PROVIDER: S-EPMC3837891 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Biochemical analysis of the role of G118R-linked dolutegravir drug resistance substitutions in HIV-1 integrase.

Quashie Peter K PK Mesplède Thibault T Han Ying-Shan YS Veres Tamar T Osman Nathan N Hassounah Said S Sloan Richard D RD Xu Hong-Tao HT Wainberg Mark A MA

Antimicrobial agents and chemotherapy 20130930 12

Drug resistance mutations (DRMs) have been reported for all currently approved anti-HIV drugs, including the latest integrase strand transfer inhibitors (INSTIs). We previously used the new INSTI dolutegravir (DTG) to select a G118R integrase resistance substitution in tissue culture and also showed that secondary substitutions emerged at positions H51Y and E138K. Now, we have characterized the impact of the G118R substitution, alone or in combination with either H51Y or E138K, on 3' processing ...[more]

PMID: 24080645

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Project description:UnlabelledDolutegravir (DTG) is the latest antiretroviral (ARV) approved for the treatment of human immunodeficiency virus (HIV) infection. The G118R substitution, previously identified with MK-2048 and raltegravir, may represent the initial substitution in a dolutegravir resistance pathway. We have found that subtype C integrase proteins have a low enzymatic cost associated with the G118R substitution, mostly at the strand transfer step of integration, compared to either subtype B or recombinant CRF02_AG proteins. Subtype B and circulating recombinant form AG (CRF02_AG) clonal viruses encoding G118R-bearing integrases were severely restricted in their viral replication capacity, and G118R/E138K-bearing viruses had various levels of resistance to dolutegravir, raltegravir, and elvitegravir. In cell-free experiments, the impacts of the H51Y and E138K substitutions on resistance and enzyme efficiency, when present with G118R, were highly dependent on viral subtype. Sequence alignment and homology modeling showed that the subtype-specific effects of these mutations were likely due to differential amino acid residue networks in the different integrase proteins, caused by polymorphic residues, which significantly affect native protein activity, structure, or function and are important for drug-mediated inhibition of enzyme activity. This preemptive study will aid in the interpretation of resistance patterns in dolutegravir-treated patients.ImportanceRecognized drug resistance mutations have never been reported for naive patients treated with dolutegravir. Additionally, in integrase inhibitor-experienced patients, only R263K and other previously known integrase resistance substitutions have been reported. Here we suggest that alternate resistance pathways may develop in non-B HIV-1 subtypes and explain how "minor" polymorphisms and substitutions in HIV integrase that are associated with these subtypes can influence resistance against dolutegravir. This work also highlights the importance of phenotyping versus genotyping when a strong inhibitor such as dolutegravir is being used. By characterizing the G118R substitution, this work also preemptively defines parameters for a potentially important pathway in some non-B HIV subtype viruses treated with dolutegravir and will aid in the inhibition of such a virus, if detected. The general inability of strand transfer-related substitutions to diminish 3' processing indicates the importance of the 3' processing step and highlights a therapeutic angle that needs to be better exploited.

Project description:Resistance associated mutations (RAMs) threaten the long-term success of combination antiretroviral therapy (cART) outcomes for HIV-1 treatment. HIV-1 Integrase (IN) strand transfer inhibitors (INSTIs) have proven to be a viable option for highly specific HIV-1 therapy. The INSTI, Dolutegravir is recommended by the World Health Organization for use as first-line cART. This study aims to understand how RAMs affect the stability of IN, as well as the binding of the drug Dolutegravir to the catalytic pocket of the protein. A homology model of HIV-1 subtype C IN was successfully constructed and validated. The site directed mutator webserver was used to predict destabilizing and/or stabilizing effects of known RAMs while FoldX confirmed any changes in protein energy upon introduction of mutation. Also, interaction analysis was performed between neighbouring residues. Three mutations known to be associated with Raltegravir, Elvitegravir and Dolutegravir resistance were selected; E92Q, G140S and Y143R, for molecular dynamics simulations. The structural quality assessment indicated high reliability of the HIV-1C IN tetrameric structure, with more than 90% confidence in modelled regions. Change in free energy for the three mutants indicated different effects, while simulation analysis showed G140S to have the largest affect on protein stability and flexibility. This was further supported by weaker non-bonded pairwise interaction energy and binding free energy values between the drug DTG and E92Q, Y143R and G140S mutants suggesting reduced binding affinity, as indicated by interaction analysis in comparison to the WT. Our findings suggest the G140S mutant has the strongest effect on the HIV-1C IN protein structure and Dolutegravir binding. To the best of our knowledge, this is the first study that uses the consensus wild type HIV-1C IN sequence to build an accurate 3D model to understand the effect of three known mutations on DTG drug binding in a South Africa context.

Dataset Information

Biochemical analysis of the role of G118R-linked dolutegravir drug resistance substitutions in HIV-1 integrase.

Publications

Biochemical analysis of the role of G118R-linked dolutegravir drug resistance substitutions in HIV-1 integrase.

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