Substrate-dependent inhibition or stimulation of HIV RNase H activity by non-nucleoside reverse transcriptase inhibitors (NNRTIs).
HIV reverse transcriptase (HIV-RT) contains two distinct protein domains catalyzing DNA polymerase and RNase H activities. Non-nucleoside reverse transcriptase inhibitor (NNRTI) binding to HIV-RT can affect RNase H activity. The structurally diverse NNRTIs capravirine, efavirenz, GW8248, TMC-125, and nevirapine all inhibited 5'-RNA directed HIV RNase H activity as partial inhibitors with maximal inhibition of 40-65%. Potencies of RNase H inhibition correlated with the respective potencies of DNA polymerase inhibition. Mutations in the NNRTI binding site (K103N, Y181C, Y188L, and K103N/Y181C) reduced the potency of RNase H inhibition, similar to their effects on DNA polymerase activity. The NNRTIs did not affect the activity of the isolated HIV RNase H domain. In contrast, 3'-DNA directed RNase H activity of HIV-RT was mechanistically distinct from 5'-RNA directed RNase H activity and was stimulated rather than inhibited by NNRTI binding to HIV-RT. Therefore, NNRTI binding to the polymerase domain of HIV-RT interferes with RNase H activity through a long-range effect, which is affected by the structure of the RNA:DNA hybrid substrate, but is independent of NNRTI compound structure and nucleic acid substrate sequence.
Hang
Julie Q
JQ
Roche Palo Alto LLC, 3431 Hillview Avenue, Palo Alto, CA 94304, USA.
Li
Yu
Y
Yang
Yanli
Y
Cammack
Nick
N
Mirzadegan
Tara
T
Klumpp
Klaus
K
D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000737:chemistry; D006678:HIV / Q000201:enzymology*; D009705:Nucleosides / Q000737:chemistry*; D018894:Reverse Transcriptase Inhibitors / Q000737:chemistry*; D016914:Ribonuclease H / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D004791:Enzyme Inhibitors; D009705:Nucleosides; D018894:Reverse Transcriptase Inhibitors; D016914:Ribonuclease H