NMR structure of the N-terminal domain of E. coli DnaB helicase: implications for structure rearrangements in the helicase hexamer
Date
1999
Authors
Weigelt, Johan
Brown, Susan Elizabeth
Miles, Caroline
Dixon, Nicholas
Otting, Gottfried
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Cell Press
Abstract
Background: DnaB is the primary replicative helicase in Escherichia coli. Native DnaB is a hexamer of identical subunits, each consisting of a larger C-terminal domain and a smaller N-terminal domain. Electron-microscopy data show hexamers with C6 or C3 symmetry, indicating large domain movements and reversible pairwise association. Results: The three-dimensional structure of the N-terminal domain of E. coli DnaB was determined by nuclear magnetic resonance (NMR) spectroscopy. Structural similarity was found with the primary dimerisation domain of a topoisomerase, the gyrase A subunit from E. coli. A monomer-dimer equilibrium was observed for the isolated N-terminal domain of DnaB. A dimer model with C2 symmetry was derived from intermolecular nuclear Overhauser effects, which is consistent with all available NMR data. Conclusions: The monomer-dimer equilibrium observed for the N-terminal domain of DnaB is likely to be of functional significance for helicase activity, by participating in the switch between C6 and C3 symmetry of the helicase hexamer.
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Keywords: DNA b; helicase; amino acid sequence; amino terminal sequence; article; dimerization; enzyme activity; enzyme structure; escherichia coli; nonhuman; nuclear magnetic resonance imaging; nucleotide sequence; priority journal; protein domain; structure analy DnaB; Helicase; NMR
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2037-12-31
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