Mecanismos de replicação da reinicialização do DNA bacteriano: mero acaso, fortuita necessidade ou design inteligente?

segunda-feira, dezembro 04, 2017

Mechanisms of bacterial DNA replication restart 

Tricia A. Windgassen Sarah R. Wessel Basudeb Bhattacharyya James L. Keck

Nucleic Acids Research, gkx1203,

Published: 30 November 2017 Article history

Received: 28 September 2017 Revision Received: 15 November 2017

Accepted: 20 November 2017

DNA replication and forked DNA structures that can be recognized by the replication restart machinery. (A) Cartoon representation of DNA replication in E. coli from the origin of replication (oriC) to the terminus (ter), depicting replication fork arrest and collapse that often occurs during this process. (B) Schematic of the DNA fork structures present at abandoned replication forks and other fork types that replication restart can recognize. These additional fork types are found during DNA repair processes, certain phage and plasmid DNA replication initiation, and during/after transcription. DNA is indicated in black (parental) and grey (nascent) with RNA shown in red. SSB is shown in orange.


Multi-protein DNA replication complexes called replisomes perform the essential process of copying cellular genetic information prior to cell division. Under ideal conditions, replisomes dissociate only after the entire genome has been duplicated. However, DNA replication rarely occurs without interruptions that can dislodge replisomes from DNA. Such events produce incompletely replicated chromosomes that, if left unrepaired, prevent the segregation of full genomes to daughter cells. To mitigate this threat, cells have evolved ‘DNA replication restart’ pathways that have been best defined in bacteria. Replication restart requires recognition and remodeling of abandoned replication forks by DNA replication restart proteins followed by reloading of the replicative DNA helicase, which subsequently directs assembly of the remaining replisome subunits. This review summarizes our current understanding of the mechanisms underlying replication restart and the proteins that drive the process in Escherichia coli (PriA, PriB, PriC and DnaT).


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