RNA helicase: a novel activity associated with a protein encoded by a positive strand RNA virus.
Most positive strand RNA viruses infecting plants and animals encode proteins containing the so-called nucleotide binding motif (NTBM) (1) in their amino acid sequences (2). As suggested from the high level of sequence similarity of these viral proteins with the recently described superfamilies of helicase-like proteins (3-5), the NTBM-containing cylindrical inclusion (CI) protein from plum pox virus (PPV), which belongs to the potyvirus group of positive strand RNA viruses, is shown to be able to unwind RNA duplexes. This activity was found to be dependent on the hydrolysis of NTP to NDP and Pi, and thus it can be considered as an RNA helicase activity. In the in vitro assay used, the PPV CI protein was only able to unwind double strand RNA substrates with 3' single strand overhangs. This result indicates that the helicase activity of the PPV CI protein functions in the 3' to 5' direction (6). To our knowledge, this is the first report on a helicase activity associated with a protein encoded by an RNA virus.
Laín
S
S
Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma, Madrid, Spain.
Riechmann
J L
JL
García
J A
JA
D000255:Adenosine Triphosphate / Q000378:metabolism; D001483:Base Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D010942:Plant Viruses / Q000201:enzymology* / Q000235:genetics; D010944:Plants / Q000382:microbiology; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D012328:RNA Viruses / Q000201:enzymology* / Q000235:genetics
D000255:Adenosine Triphosphate; D012316:RNA Nucleotidyltransferases; D020365:RNA Helicases