Publication Date:
2015-09-01
Description:
Eukaryotic DNA replication terminates when replisomes from adjacent replication origins converge. Termination involves local completion of DNA synthesis, decatenation of daughter molecules and replisome disassembly. Termination has been difficult to study because termination events are generally asynchronous and sequence nonspecific. To overcome these challenges, we paused converging replisomes with a site-specific barrier in Xenopus egg extracts. Upon removal of the barrier, forks underwent synchronous and site-specific termination, allowing mechanistic dissection of this process. We show that DNA synthesis does not slow detectably as forks approach each other, and that leading strands pass each other unhindered before undergoing ligation to downstream lagging strands. Dissociation of the replicative CMG helicase (comprising CDC45, MCM2-7 and GINS) occurs only after the final ligation step, and is not required for completion of DNA synthesis, strongly suggesting that converging CMGs pass one another and dissociate from double-stranded DNA. This termination mechanism allows rapid completion of DNA synthesis while avoiding premature replisome disassembly.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4575634/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4575634/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dewar, James M -- Budzowska, Magda -- Walter, Johannes C -- GM62267/GM/NIGMS NIH HHS/ -- GM80676/GM/NIGMS NIH HHS/ -- R01 GM062267/GM/NIGMS NIH HHS/ -- R01 GM080676/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2015 Sep 17;525(7569):345-50. doi: 10.1038/nature14887. Epub 2015 Aug 31.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA. ; Howard Hughes Medical Institute, Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26322582" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Cell Extracts/pharmacology
;
DNA/biosynthesis/metabolism
;
DNA Helicases/metabolism
;
*DNA Replication/drug effects
;
DNA-Binding Proteins/metabolism
;
DNA-Directed DNA Polymerase/metabolism
;
Multienzyme Complexes/metabolism
;
Oocytes/*metabolism
;
*Xenopus laevis
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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