RNase H domain mutations affect the interaction between Moloney murine leukemia virus reverse transcriptase and its primer-template.

The active sites for the polymerase and nuclease activities of Moloney murine leukemia virus (M-MuLV) reverse transcriptase (RT) reside in separate domains of a single polypeptide. We have studied the effects of RNase H domain mutations on DNA polymerase activity. These mutant RTs displayed decreased processivity of DNA synthesis. We also compared complexes formed between primer-templates and mutant and wild-type reverse transcriptase (RT). Although M-MuLV RT is monomeric in solution, two molecules of RT bound DNA cooperatively, suggesting that M-MuLV RT binds primer-template as a dimer. Some mutant RTs with decreased processivity failed to form the putative dimer.