Premium
Step‐by‐step progress toward understanding the hepatitis C virus RNA helicase
Author(s) -
Frick David N.
Publication year - 2006
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.21200
Subject(s) - helicase , ns3 , nucleic acid , rna , biology , dna , base pair , computational biology , nucleotide , rna helicase a , biochemistry , enzyme , microbiology and biotechnology , chemistry , protease , gene
Helicases are a ubiquitous class of enzymes involved in nearly all aspects of DNA and RNA metabolism. Despite recent progress in understanding their mechanism of action, limited resolution has left inaccessible the detailed mechanisms by which these enzymes couple the rearrangement of nucleic acid structures to the binding and hydrolysis of ATP. Observing individual mechanistic cycles of these motor proteins is central to understanding their cellular functions. Here we follow in real time, at a resolution of two base pairs and 20 ms, the RNA translocation and unwinding cycles of a hepatitis C virus helicase (NS3) monomer. NS3 is a representative superfamily‐2 helicase essential for viral replication, and therefore a potentially important drug target. We show that the cyclic movement of NS3 is coordinated by ATP in discrete steps of 11 +/‐ 3 base pairs, and that actual unwinding occurs in rapid smaller substeps of 3.6 +/‐ 1.3 base pairs, also triggered by ATP binding, indicating that NS3 might move like an inchworm. This ATP‐coupling mechanism is likely to be applicable to other non‐hexameric helicases involved in many essential cellular functions. The assay developed here should be useful in investigating a broad range of nucleic acid translocation motors.