title: The importance of the Q motif in the ATPase activity of a viral helicase.
abstract: NS3 proteins of flaviviruses contain motifs which indicate that they possess protease and helicase activities. The helicases are members of the DExD/H box helicase superfamily and NS3 proteins from some flaviviruses have been shown to possess ATPase and helicase activities in vitro. The Q motif is a recently recognised cluster of nine amino acids common to most DExD/H box helicases which is proposed to regulate ATP binding and hydrolysis. In addition a conserved residue occurs 17 amino acids upstream of the Q motif ('+17'). We have analysed full-length and truncated NS3 proteins from Powassan virus (a tick-borne flavivirus) to investigate the role that the Q motif plays in the hydrolysis of ATP by a viral helicase. The Q motif appears to be essential for the activity of Powassan virus NS3 ATPase, however NS3 deletion mutants that contain the Q motif but lack the '+17' amino acid have ATPase activity albeit at a reduced level.
authors: Department of Medicine, Faculty of Medicine, Imperial College London, St Mary's Hospital Campus, London W2 1NY, UK.
authors: J-P
authors: JP
authors: Gallivan
authors: Michael J
authors: MJ
authors: McGarvey
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs / Q000502:physiology*; D000818:Animals; D001345:Autoradiography; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004669:Encephalitis Viruses, Tick-Borne / Q000201:enzymology*; D004926:Escherichia coli / Q000378:metabolism; D006868:Hydrolysis; D051379:Mice; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D012367:RNA, Viral; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases