Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity.
RecQ helicases are essential for the maintenance of chromosome stability. In addition to DNA unwinding, some RecQ enzymes have an intrinsic DNA strand annealing activity. The function of this dual enzymatic activity and the mechanism that regulates it is, however, unknown. Here, we describe two quat...
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doaj-f6fc8feed45645e59e75881fe6900f442021-07-02T16:25:50ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852007-02-0152e2010.1371/journal.pbio.0050020Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity.Laura MuzzoliniFabienne BeuronArdan PatwardhanVenkateswarlu PopuriSheng CuiBenedetta NiccoliniMathieu RappasPaul S FreemontAlessandro VindigniRecQ helicases are essential for the maintenance of chromosome stability. In addition to DNA unwinding, some RecQ enzymes have an intrinsic DNA strand annealing activity. The function of this dual enzymatic activity and the mechanism that regulates it is, however, unknown. Here, we describe two quaternary forms of the human RECQ1 helicase, higher-order oligomers consistent with pentamers or hexamers, and smaller oligomers consistent with monomers or dimers. Size exclusion chromatography and transmission electron microscopy show that the equilibrium between the two assembly states is affected by single-stranded DNA (ssDNA) and ATP binding, where ATP or ATPgammaS favors the smaller oligomeric form. Our three-dimensional electron microscopy reconstructions of human RECQ1 reveal a complex cage-like structure of approximately 120 A x 130 A with a central pore. This oligomeric structure is stabilized under conditions in which RECQ1 is proficient in strand annealing. In contrast, competition experiments with the ATPase-deficient K119R and E220Q mutants indicate that RECQ1 monomers, or tight binding dimers, are required for DNA unwinding. Collectively, our findings suggest that higher-order oligomers are associated with DNA strand annealing, and lower-order oligomers with DNA unwinding.https://doi.org/10.1371/journal.pbio.0050020 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Laura Muzzolini Fabienne Beuron Ardan Patwardhan Venkateswarlu Popuri Sheng Cui Benedetta Niccolini Mathieu Rappas Paul S Freemont Alessandro Vindigni |
spellingShingle |
Laura Muzzolini Fabienne Beuron Ardan Patwardhan Venkateswarlu Popuri Sheng Cui Benedetta Niccolini Mathieu Rappas Paul S Freemont Alessandro Vindigni Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity. PLoS Biology |
author_facet |
Laura Muzzolini Fabienne Beuron Ardan Patwardhan Venkateswarlu Popuri Sheng Cui Benedetta Niccolini Mathieu Rappas Paul S Freemont Alessandro Vindigni |
author_sort |
Laura Muzzolini |
title |
Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity. |
title_short |
Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity. |
title_full |
Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity. |
title_fullStr |
Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity. |
title_full_unstemmed |
Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity. |
title_sort |
different quaternary structures of human recq1 are associated with its dual enzymatic activity. |
publisher |
Public Library of Science (PLoS) |
series |
PLoS Biology |
issn |
1544-9173 1545-7885 |
publishDate |
2007-02-01 |
description |
RecQ helicases are essential for the maintenance of chromosome stability. In addition to DNA unwinding, some RecQ enzymes have an intrinsic DNA strand annealing activity. The function of this dual enzymatic activity and the mechanism that regulates it is, however, unknown. Here, we describe two quaternary forms of the human RECQ1 helicase, higher-order oligomers consistent with pentamers or hexamers, and smaller oligomers consistent with monomers or dimers. Size exclusion chromatography and transmission electron microscopy show that the equilibrium between the two assembly states is affected by single-stranded DNA (ssDNA) and ATP binding, where ATP or ATPgammaS favors the smaller oligomeric form. Our three-dimensional electron microscopy reconstructions of human RECQ1 reveal a complex cage-like structure of approximately 120 A x 130 A with a central pore. This oligomeric structure is stabilized under conditions in which RECQ1 is proficient in strand annealing. In contrast, competition experiments with the ATPase-deficient K119R and E220Q mutants indicate that RECQ1 monomers, or tight binding dimers, are required for DNA unwinding. Collectively, our findings suggest that higher-order oligomers are associated with DNA strand annealing, and lower-order oligomers with DNA unwinding. |
url |
https://doi.org/10.1371/journal.pbio.0050020 |
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