The Cdc45/Mcm2-7/GINS (CMG) helicase separates DNA strands during replication in eukaryotes. How the CMG is assembled and engages DNA substrates remains unclear. Using electron microscopy, we have determined the structure of the CMG in the presence of ATPγS and a DNA duplex bearing a 3′ single-stranded tail. The structure shows that the MCM subunits of the CMG bind preferentially to single-stranded DNA, establishes the polarity by which DNA enters into the Mcm2-7 pore, and explains how Cdc45 helps prevent DNA from dissociating from the helicase. The Mcm2-7 subcomplex forms a cracked-ring, right-handed spiral when DNA and nucleotide are bound, revealing unexpected congruencies between the CMG and both bacterial DnaB helicases and the AAA+ motor of the eukaryotic proteasome. The existence of a subpopulation of dimeric CMGs establishes the subunit register of Mcm2-7 double hexamers and together with the spiral form highlights how Mcm2-7 transitions through different conformational and assembly states as it matures into a functional helicase.
DNA binding polarity, dimerization, and ATPase ring remodeling in the CMG helicase of the eukaryotic replisome / A. Costa, L. Renault, P. Swuec, T. Petojevic, J.J. Pesavento, I. Ilves, K. MacLellan-Gibson, R.A. Fleck, M.R. Botchan, J.M. Berger. - In: ELIFE. - ISSN 2050-084X. - 3(2014 Aug), pp. e03273.1-e03273.17.
|Titolo:||DNA binding polarity, dimerization, and ATPase ring remodeling in the CMG helicase of the eukaryotic replisome|
|Parole Chiave:||AAA+ ATPase; DNA replication; Mcm2-7; helicase; motor proteins; replication fork; Adenosine Triphosphatases; Adenosine Triphosphate; Animals; Cell Cycle Proteins; Chromosomal Proteins, Non-Histone; DNA; DNA Replication; DNA, Single-Stranded; DNA-Binding Proteins; Drosophila Proteins; Drosophila melanogaster; Eukaryotic Cells; Microscopy, Electron; Minichromosome Maintenance Proteins; Models, Molecular; Multiprotein Complexes; Protein Binding; Protein Multimerization; Protein Structure, Quaternary; Protein Structure, Tertiary; Protein Subunits; RNA Splicing Factors; RNA-Binding Proteins; Repressor Proteins; Neuroscience (all); Biochemistry, Genetics and Molecular Biology (all); Immunology and Microbiology (all)|
|Settore Scientifico Disciplinare:||Settore BIO/10 - Biochimica|
|Data di pubblicazione:||ago-2014|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.7554/eLife.03273|
|Appare nelle tipologie:||01 - Articolo su periodico|