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Abstract
Chandipura virus (CHPV) is an emerging human pathogen associated with acute encephalitis and is related closely to vesicular stomatitis virus (VSV), a prototype rhabdovirus. Here, we demonstrate that the RNA polymerase L protein of CHPV exhibits a VSV-like RNA : GDP polyribonucleotidyltransferase (PRNTase) activity, which transfers the 5′-monophosphorylated (p-) viral mRNA start sequence to GDP to produce a capped RNA, and that the conserved HR motif in the CHPV L protein is essential for the PRNTase activity. Interestingly, the CHPV L protein was found to form two distinct SDS-resistant complexes with the CHPV mRNA and leader RNA start sequences; mutations in the HR motif significantly reduced the formation of the former complex (a putative covalent enzyme–pRNA intermediate in the PRNTase reaction), but not the latter complex. These results suggest that the rhabdoviral L proteins universally use the active-site HR motif for the PRNTase reaction at the step of the enzyme–pRNA intermediate formation.
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