Biomedical subjects

Katie L Moore

Publications and source records attributed to Katie L Moore.

3 recordsLinked to original sources

PubMed2006

Potent nonnucleoside reverse transcriptase inhibitors target HIV-1 Gag-Pol.

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) target HIV-1 reverse transcriptase (RT) by binding to a pocket in RT that is close to, but distinct, from the DNA polymerase active site and prevent the synthesis of viral cDNA. NNRTIs, in particular, those that are potent inhibitors of RT polymerase activity, can also act as chemical enhancers of the enzyme's inter-subunit interactions. However, the consequences of this chemical enhancement effect on HIV-1 replication are not understood. Here, we show that the potent NNRTIs efavirenz, TMC120, and TMC125, but not nevirapine or delavirdine, inhibit the late stages of HIV-1 replication. These potent NNRTIs enhanced the intracellular processing of Gag and Gag-Pol polyproteins, and this was associated with a decrease in viral particle production from HIV-1-transfected cells. The increased polyprotein processing is consistent with premature activation of the HIV-1 protease by NNRTI-enhanced Gag-Pol multimerization through the embedded RT sequence. These findings support the view that Gag-Pol multimerization is an important step in viral assembly and demonstrate that regulation of Gag-Pol/Gag-Pol interactions is a novel target for small molecule inhibitors of HIV-1 production. Furthermore, these drugs can serve as useful probes to further understand processes involved in HIV-1 particle assembly and maturation.

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PubMed2005

Efavirenz enhances the proteolytic processing of an HIV-1 pol polyprotein precursor and reverse transcriptase homodimer formation.

The non-nucleoside reverse transcriptase inhibitor, efavirenz (EFV), is a potent enhancer of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) p66/p51 heterodimerization. While the mechanism of RT heterodimer formation in HIV-1 infected cells is not completely understood, it has been speculated that Gag-Pol/Gag-Pol and/or RT homodimer interactions may represent important intermediates in the pathway. To elucidate whether EFV impacts on these interactions, we have evaluated the effects of this drug on RT homodimer interactions and HIV-1 Gag-Pol processing. EFV, but not nevirapine, significantly enhanced RT p66/p66 and p51/p51 homodimer interactions and accelerated the proteolytic cleavage of a model HIV-1 Pol polyprotein precursor expressed in bacteria. These data suggest that potent mediators of RT dimerization might interfere with the late-stages of viral replication.

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PubMed2005

Mutations that abrogate human immunodeficiency virus type 1 reverse transcriptase dimerization affect maturation of the reverse transcriptase heterodimer.

The specific impact of mutations that abrogate human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) dimerization on virus replication is not known, as mutations shown previously to inhibit RT dimerization also impact Gag-Pol stability, resulting in pleiotropic effects on HIV-1 replication. We have previously characterized mutations at codon 401 in the HIV-1 RT tryptophan repeat motif that abrogate RT dimerization in vitro, leading to a loss in polymerase activity. The introduction of the RT dimerization-inhibiting mutations W401L and W401A into HIV-1 resulted in the formation of noninfectious viruses with reduced levels of both virion-associated and intracellular RT activity compared to the wild-type virus and the W401F mutant, which does not inhibit RT dimerization in vitro. Steady-state levels of the p66 and p51 RT subunits in viral lysates of the W401L and W401A mutants were reduced, but no significant decrease in Gag-Pol was observed compared to the wild type. In contrast, there was a decrease in processing of p66 to p51 in cell lysates for the dimerization-defective mutants compared to the wild type. The treatment of transfected cells with indinavir suggested that the HIV-1 protease contributed to the degradation of virion-associated RT subunits. These data demonstrate that mutations near the RT dimer interface that abrogate RT dimerization in vitro result in the production of replication-impaired viruses without detectable effects on Gag-Pol stability or virion incorporation. The inhibition of RT activity is most likely due to a defect in RT maturation, suggesting that RT dimerization represents a valid drug target for chemotherapeutic intervention.

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