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pH-Controlled Quaternary States of Hexameric DnaB Helicase

Donate, Luis Enrique; Llorca, O; Barcena, M; Brown, Susan Elizabeth; Dixon, Nicholas; Carazo, Jose-Maria

Description

DnaB is the major helicase in the Escherichia coli replisome. It is a homohexameric enzyme that interacts with many other replisomal proteins and cofactors. It is usually loaded onto a single strand of DNA at origins of replication from its complex with its loading partner DnaC, then translocates in the 5' to 3' direction, unwinding duplex DNA in an NTP-driven process. Quaternary polymorphism has been described for the DnaB oligomer, a feature it has in common with some other hexameric...[Show more]

dc.contributor.authorDonate, Luis Enrique
dc.contributor.authorLlorca, O
dc.contributor.authorBarcena, M
dc.contributor.authorBrown, Susan Elizabeth
dc.contributor.authorDixon, Nicholas
dc.contributor.authorCarazo, Jose-Maria
dc.date.accessioned2015-12-13T23:18:32Z
dc.identifier.issn0022-2836
dc.identifier.urihttp://hdl.handle.net/1885/90221
dc.description.abstractDnaB is the major helicase in the Escherichia coli replisome. It is a homohexameric enzyme that interacts with many other replisomal proteins and cofactors. It is usually loaded onto a single strand of DNA at origins of replication from its complex with its loading partner DnaC, then translocates in the 5' to 3' direction, unwinding duplex DNA in an NTP-driven process. Quaternary polymorphism has been described for the DnaB oligomer, a feature it has in common with some other hexameric helicases. In the present work, electron microscopy and indepth rotational analysis studies of negatively stained specimens has allowed the establishment of conditions that govern the transition between the two different rotational symmetry states (C3 and C6) of DnaB. It is shown: (a) that the pH value of the sample buffer, within the physiological range, dictates the quaternary organisation of the DnaB oligomer; (b) that the pH-induced transition is fully reversible; (c) that the type of adenine nucleotide complexed to DnaB, whether hydrolysable or not, does not affect its quaternary architecture; (d) that the DnaB · DnaC complex exists only as particles with C3 symmetry; and (e) that DnaC interacts only with DnaB particles that have C3 symmetry. Structural consequences of this quaternary polymorphism, as well as its functional implications for helicase activity, are discussed. (C) 2000 Academic Press.
dc.publisherElsevier
dc.sourceJournal of Molecular Biology
dc.subjectKeywords: DNA B; helicase; article; DNA binding; DNA polymorphism; DNA replication; DNA structure; enzyme activity; Escherichia coli; pH; priority journal; Adenosine Diphosphate; Adenosine Triphosphate; Adenylyl Imidodiphosphate; Bacterial Proteins; DNA Helicases; DNA replication; DnaB; Electron microscopy; Hexameric helicases and quaternary polymorphism; Image analysis
dc.titlepH-Controlled Quaternary States of Hexameric DnaB Helicase
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume303
dc.date.issued2000
local.identifier.absfor030503 - Organic Chemical Synthesis
local.identifier.ariespublicationMigratedxPub20523
local.type.statusPublished Version
local.contributor.affiliationDonate, Luis Enrique, Universidad Autonoma de Madrid
local.contributor.affiliationLlorca, O, Centro Nacional de Biotecnología (CSIC)
local.contributor.affiliationBarcena, M, Universidad Autonoma de Madrid
local.contributor.affiliationBrown, Susan Elizabeth, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationDixon, Nicholas, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationCarazo, Jose-Maria, Universidad Autonoma de Madrid
local.description.embargo2037-12-31
local.bibliographicCitation.issue3
local.bibliographicCitation.startpage383
local.bibliographicCitation.lastpage393
local.identifier.doi10.1006/jmbi.2000.4132
dc.date.updated2015-12-12T08:57:14Z
local.identifier.scopusID2-s2.0-0034721948
CollectionsANU Research Publications

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