The basic loop of the RNase H domain of MLV RT is important both for RNase H and for polymerase activity.
Escherichia coli RNase H has a basic extension that is involved in binding nucleic acid substrates. This basic extension is present in the RNase H of Moloney murine leukemia virus reverse transcriptase (MLV RT), but has been deleted from the RNase H of HIV-1 RT. Previous work showed that removing the basic loop from MLV RT (the mutant is called DeltaC) blocked viral replication; however, DeltaC MLV RT retained RNase H activity in an in situ gel assay. We prepared recombinant DeltaC MLV RT and compared its activity to wild-type MLV RT. The DeltaC mutant is impaired in both polymerase and RNase H activity; the pattern of defects suggests that the basic loop is involved in the binding of MLV RT to a heteropolymeric template-primer.
HIV Drug Resistance Program, National Cancer Institute-Frederick, Maryland 21702-1201, USA.
P L
PL
Boyer
H Q
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Gao
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Frank
P K
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Clark
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Hughes
D000818:Animals; D020134:Catalytic Domain; D004259:DNA-Directed DNA Polymerase / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008979:Moloney murine leukemia virus / Q000201:enzymology*; D009154:Mutation; D012194:RNA-Directed DNA Polymerase / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D016914:Ribonuclease H / Q000235:genetics* / Q000378:metabolism
D011994:Recombinant Proteins; D012194:RNA-Directed DNA Polymerase; D004259:DNA-Directed DNA Polymerase; D016914:Ribonuclease H