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Enhanced stability of monomer fold correlates with extreme drug resistance of HIV-1 protease.

ABSTRACT: During treatment, mutations in HIV-1 protease (PR) are selected rapidly that confer resistance by decreasing affinity to clinical protease inhibitors (PIs). As these unique drug resistance mutations can compromise the fitness of the virus to replicate, mutations that restore conformational stability and activity while retaining drug resistance are selected on further evolution. Here we identify several compensating mechanisms by which an extreme drug-resistant mutant bearing 20 mutations (PR20) with >5-fold increased Kd and >4000-fold decreased affinity to the PI darunavir functions. (1) PR20 cleaves, albeit poorly, Gag polyprotein substrates essential for viral maturation. (2) PR20 dimer, which exhibits distinctly enhanced thermal stability, has highly attenuated autoproteolysis, thus likely prolonging its lifetime in vivo. (3) The enhanced stability of PR20 results from stabilization of the monomer fold. Both monomeric PR20(T26A) and dimeric PR20 exhibit Tm values 6-7.5 °C higher than those for their PR counterparts. Two specific mutations in PR20, L33F and L63P at sites of autoproteolysis, increase the Tm of monomeric PR(T26A) by ~8 °C, similar to PR20(T26A). However, without other compensatory mutations as seen in PR20, L33F and L63P substitutions, together, neither restrict autoproteolysis nor significantly reduce binding affinity to darunavir. To determine whether dimer stability contributes to binding affinity for inhibitors, we examined single-chain dimers of PR and PR(D25N) in which the corresponding identical monomer units were covalently linked by GGSSG sequence. Linking of the subunits did not appreciably change the ?Tm on inhibitor binding; thus stabilization by tethering appears to have little direct effect on enhancing inhibitor affinity.

SUBMITTER: Louis JM

PROVIDER: S-EPMC3888107 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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Enhanced stability of monomer fold correlates with extreme drug resistance of HIV-1 protease.

Louis John M JM Tözsér József J Roche Julien J Matúz Krisztina K Aniana Annie A Sayer Jane M JM

Biochemistry 20131015 43

During treatment, mutations in HIV-1 protease (PR) are selected rapidly that confer resistance by decreasing affinity to clinical protease inhibitors (PIs). As these unique drug resistance mutations can compromise the fitness of the virus to replicate, mutations that restore conformational stability and activity while retaining drug resistance are selected on further evolution. Here we identify several compensating mechanisms by which an extreme drug-resistant mutant bearing 20 mutations (PR20) ...[more]

PMID: 24079831

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Project description:Sociodemographic correlates of engagement in human immunodeficiency virus (HIV) care are well studied, however the association with accessing drug resistance testing (DRT) and the development of drug resistance have not been characterized. Between 1996-2014, 11 801 HIV patients accessing therapy in British Columbia were observed longitudinally. A subset of 9456 patients had testable viral load; of these 8398 were linked to census data. Sociodemographic (census tract-level) and clinical (individual-level) correlates of DRT were assessed using multivariable General Estimating Equation logistic regression adjusted odds ratios (aOR). The mean number of tests per patient was 2.1 (Q1-Q3; 0-3). Separately, any drug resistance was determined using IAS-USA (2013) list for 5703 initially treatment naïve patients without baseline resistance; 5175 were census-linked (mean of 1.5 protease-reverse transcriptase sequences/patient, Q1-Q3; 0-2). Correlates of detecting drug resistance in this subset were analyzed using Cox PH regression adjusted hazard ratios (aHR). Our results indicate baseline CD4 <200 cells/?L (aOR: 1.5, 1.3-1.6), nRTI-only baseline regimens (aOR: 1.4, 1.3-1.6), and unknown (therapy initiation before routine pVL in BC) baseline pVL (aOR: 1.8, 1.5-2.1) were among individual-level clinical covariates strongly associated with having accessed DRT; while imperfect adherence (aHR: 2.2, 1.9-2.5), low baseline CD4 count (aHR: 1.9, 1.6-2.3), and high baseline pVL (aHR: 2.0, 1.6-2.6) were associated with a higher likelihood of developing drug resistance. A higher median income (aOR: 0.83, 0.77-0.89) and higher percentage of those with aboriginal ancestry (aOR: 0.85, 0.76-0.95) were census tract-level sociodemographic covariates associated with decreased access to DRT. Similarly, aboriginal ancestry (aHR: 1.2, 1.1-1.5) was associated with development of drug resistance. In conclusion, clinical covariates continue to be the strongest correlates of development of drug resistance and access to DRT for individuals. Regions of high median income and high aboriginal ancestry were weak census-level sociodemographic indicators of reduced DRT uptake, however high aboriginal ancestry was the only sociodemographic indicator for development of drug resistance.

Dataset Information

Enhanced stability of monomer fold correlates with extreme drug resistance of HIV-1 protease.

Publications

Enhanced stability of monomer fold correlates with extreme drug resistance of HIV-1 protease.

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