A flexible brace maintains the assembly of a hexameric replicative helicase during DNA unwinding

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dc.contributor.authorWhelan, F.
dc.contributor.authorStead, J.A.
dc.contributor.authorShkumatov, A.V.
dc.contributor.authorSvergun, D.I.
dc.contributor.authorSanders, C.M.
dc.contributor.authorAntson, A.A.
dc.date.issued2012
dc.description.abstractThe mechanism of DNA translocation by papillomavirus E1 and polyomavirus LTag hexameric helicases involves consecutive remodelling of subunit-subunit interactions around the hexameric ring. Our biochemical analysis of E1 helicase demonstrates that a 26-residue C-terminal segment is critical for maintaining the hexameric assembly. As this segment was not resolved in previous crystallographic analysis of E1 and LTag hexameric helicases, we determined the solution structure of the intact hexameric E1 helicase by Small Angle X-ray Scattering. We find that the C-terminal segment is flexible and occupies a cleft between adjacent subunits in the ring. Electrostatic potential calculations indicate that the negatively charged C-terminus can bridge the positive electrostatic potentials of adjacent subunits. Our observations support a model in which the C-terminal peptide serves as a flexible 'brace' maintaining the oligomeric state during conformational changes associated with ATP hydrolysis. We argue that these interactions impart processivity to DNA unwinding. Sequence and disorder analysis suggest that this mechanism of hexamer stabilization would be conserved among papillomavirus E1 and polyomavirus LTag hexameric helicases.
dc.description.statementofresponsibilityFiona Whelan, Jonathan A. Stead, Alexander V. Shkumatov, Dmitri I. Svergun, Cyril M. Sanders, Alfred A. Antson
dc.identifier.citationNucleic Acids Research (NAR), 2012; 40(5):2271-2283
dc.identifier.doi10.1093/nar/gkr906
dc.identifier.issn0305-1048
dc.identifier.issn1362-4962
dc.identifier.orcidWhelan, F. [0000-0002-0791-6850]
dc.identifier.urihttp://hdl.handle.net/2440/123126
dc.language.isoen
dc.publisherOxford University Press
dc.rightsThe Author(s) 2011. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
dc.source.urihttps://doi.org/10.1093/nar/gkr906
dc.subjectDNA Helicases
dc.subjectDNA-Binding Proteins
dc.subjectProtein Subunits
dc.subjectViral Proteins
dc.subjectX-Ray Diffraction
dc.subjectSequence Deletion
dc.subjectAmino Acid Sequence
dc.subjectConserved Sequence
dc.subjectProtein Structure, Tertiary
dc.subjectModels, Molecular
dc.subjectMolecular Sequence Data
dc.subjectScattering, Small Angle
dc.subjectProtein Multimerization
dc.subjectStatic Electricity
dc.titleA flexible brace maintains the assembly of a hexameric replicative helicase during DNA unwinding
dc.typeJournal article
pubs.publication-statusPublished

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