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RNase H activity associated with reverse transcriptase from feline immunodeficiency virus.
R C Cronn1, J D Whitmer, T W North
1Division of Biological Sciences, University of Montana, Missoula 59812-1002.
Journal of Virology
|February 1, 1992
Summary
Feline and human immunodeficiency virus reverse transcriptases share similar RNase H enzymatic properties and inhibition by dextran sulfates. This suggests a conserved region in these enzymes, impacting inhibitor interactions.
Area of Science:
- Virology
- Molecular Biology
- Enzymology
Background:
- Retroviral reverse transcription necessitates RNase H activity for genome replication.
- RNase H is crucial for template switching and primer generation during reverse transcription.
Purpose of the Study:
- To compare the enzymatic characteristics of RNase H from feline immunodeficiency virus (FIV) and human immunodeficiency virus (HIV).
- To investigate the inhibitory effects of dextran sulfates on FIV and HIV RNase H and reverse transcriptase (RT) activities.
Main Methods:
- Enzymatic assays were performed to determine substrate and cation preferences for FIV and HIV RNase H.
- Hydrolysis products of FIV RNase H activity were analyzed.
- Inhibition constants for dextran sulfates were measured for both FIV and HIV RNase H and RT activities.
Main Results:
- Both FIV and HIV RNase H enzymes preferred poly[3H](rG) . poly(dC) over poly[3H](rA) . poly(dT) and Mg2+ over Mn2+.
- FIV RNase H produced hydrolysis products of 1–6 nucleotides, similar to HIV.
- Dextran sulfates inhibited both FIV and HIV RNase H and RT activities, with nearly identical inhibition constants for dextran sulfate 500,000.
Conclusions:
- Feline immunodeficiency virus and human immunodeficiency virus reverse transcriptases exhibit conserved enzymatic properties.
- A conserved region in FIV and HIV RTs is sensitive to larger dextran sulfates.
- Dextran sulfate 8,000 may interact with a different site or via a distinct mechanism on these enzymes.