title: Single-base pair unwinding and asynchronous RNA release by the hepatitis C virus NS3 helicase.
abstract: Nonhexameric helicases use adenosine triphosphate (ATP) to unzip base pairs in double-stranded nucleic acids (dsNAs). Studies have suggested that these helicases unzip dsNAs in single-base pair increments, consuming one ATP molecule per base pair, but direct evidence for this mechanism is lacking. We used optical tweezers to follow the unwinding of double-stranded RNA by the hepatitis C virus NS3 helicase. Single-base pair steps by NS3 were observed, along with nascent nucleotide release that was asynchronous with base pair opening. Asynchronous release of nascent nucleotides rationalizes various observations of its dsNA unwinding and may be used to coordinate the translocation speed of NS3 along the RNA during viral replication.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA. chengwe@umich.edu
authors.forename: Wei
authors.initials: W
authors.lastname: Cheng
authors.forename: Srikesh G
authors.initials: SG
authors.lastname: Arunajadai
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Moffitt
authors.forename: Ignacio
authors.initials: I
authors.lastname: Tinoco
authors.forename: Carlos
authors.initials: C
authors.lastname: Bustamante
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000465:Algorithms; D020029:Base Pairing; D016174:Hepacivirus / Q000201:enzymology*; D007700:Kinetics; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D052898:Optical Tweezers; D020365:RNA Helicases / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000737:chemistry / Q000378:metabolism*; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000255:Adenosine Triphosphate; D020365:RNA Helicases; D012330:RNA, Double-Stranded; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases