Recruitment to stalled replication forks of the PriA DNA helicase and replisome-loading activities is essential for survival

Gabbai, Carolina B.; Marians, Kenneth J.

doi:10.1016/j.dnarep.2009.12.009

Cited by 96 publications

(105 citation statements)

References 87 publications

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“…Thus, the chromosome is divided into two replichores within each of which replication proceeds in a polar fashion from oriC toward ter. However, the two replisome complexes meeting within the terminus area may not be those assembled at oriC, but new complexes assembled following the rescue of stalled or damaged forks (Gabbai and Marians 2010).…”

Section: R Eplication Of the Escherichia Coli Chromosomementioning

confidence: 99%

RecG Protein and Single-Strand DNA Exonucleases Avoid Cell Lethality Associated With PriA Helicase Activity inEscherichia coli

et al. 2010

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Replication of the Escherichia coli chromosome usually initiates at a single origin (oriC) under control of DnaA. Two forks are established and move away in opposite directions. Replication is completed when these meet in a broadly defined terminus area half way around the circular chromosome. RecG appears to consolidate this arrangement by unwinding D-loops and R-loops that PriA might otherwise exploit to initiate replication at other sites. It has been suggested that without RecG such replication generates 39 flaps as the additional forks collide and displace nascent leading strands, providing yet more potential targets for PriA. Here we show that, to stay alive, cells must have either RecG or a 39 single-stranded DNA (ssDNA) exonuclease, which can be exonuclease I, exonuclease VII, or SbcCD. Cells lacking all three nucleases are inviable without RecG. They also need RecA recombinase and a Holliday junction resolvase to survive rapid growth, but SOS induction, although elevated, is not required. Additional requirements for Rep and UvrD are identified and linked with defects in DNA mismatch repair and with the ability to cope with conflicts between replication and transcription, respectively. Eliminating PriA helicase activity removes the requirement for RecG. The data are consistent with RecG and ssDNA exonucleases acting to limit PriA-mediated re-replication of the chromosome and the consequent generation of linear DNA branches that provoke recombination and delay chromosome segregation.

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Section: R Eplication Of the Escherichia Coli Chromosomementioning

confidence: 99%

RecG Protein and Single-Strand DNA Exonucleases Avoid Cell Lethality Associated With PriA Helicase Activity inEscherichia coli

et al. 2010

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“…In this recognition step, PriA binds to duplex parental DNA and can accommodate either duplex or gapped leadingand lagging-strand DNA in branched replication fork structures (7-10). PriA's ability to recognize multiple DNA structures appears to provide the flexibility needed for replication restart to be initiated on structures ranging from simple replication forks to D-loops that are produced by recombinational repair of dsDNA breaks (5,6,10). However, the structural mechanism by which PriA manages to bind to this array of substrates is unknown.…”

mentioning

confidence: 99%

“…Replication restart in bacteria is orchestrated by the multifunctional PriA DNA helicase (5,6). The process is initiated by PriA binding to abandoned DNA replication forks or other appropriate replication reinitiation sites in a structure-specific manner.…”

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confidence: 99%

Structural mechanisms of PriA-mediated DNA replication restart

Bhattacharyya

George

Thurmes

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Collisions between cellular DNA replication machinery (replisomes) and damaged DNA or immovable protein complexes can dissociate replisomes before the completion of replication. This potentially lethal problem is resolved by cellular "replication restart" reactions that recognize the structures of prematurely abandoned replication forks and mediate replisomal reloading. In bacteria, this essential activity is orchestrated by the PriA DNA helicase, which identifies replication forks via structure-specific DNA binding and interactions with fork-associated ssDNA-binding proteins (SSBs). However, the mechanisms by which PriA binds replication fork DNA and coordinates subsequent replication restart reactions have remained unclear due to the dearth of high-resolution structural information available for the protein. Here, we describe the crystal structures of full-length PriA and PriA bound to SSB. The structures reveal a modular arrangement for PriA in which several DNA-binding domains surround its helicase core in a manner that appears to be poised for binding to branched replication fork DNA structures while simultaneously allowing complex formation with SSB. PriA interaction with SSB is shown to modulate SSB/DNA complexes in a manner that exposes a potential replication initiation site. From these observations, a model emerges to explain how PriA links recognition of diverse replication forks to replication restart.X-ray crystal structure | single-molecule FRET

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“…Subsequent studies by many laboratories have elaborated the genetic pathways involved in the processing and repair of stalled replication forks (for reviews, see Refs. [5][6][7][8][9][10][11]. A central feature of many of the models described is one in which the nascent strands at the stalled fork have been unwound from the respective parental template strand and paired together.…”

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confidence: 99%

“…In a topologically constrained molecule, positive supercoiling will provide a strong driving force for spontaneous RFR (14,15). With respect to rescue of the stalled fork (5)(6)(7)(8)(9)(10)(11), the HJ formed can be cleaved by the HJ resolvase, RuvC (16), resulting in rescue of replication by homologous recombination-directed DNA replication, whereby a recombinant joint molecule is formed between the two sister chromosomes, and the replisome is reloaded by a PriA-directed pathway downstream of the damage. In cases where the 5Ј-end of the last Okazaki fragment is further downstream than the 3Ј-end of a stalled nascent leading strand, a template strand switch can occur in the regressed intermediate, extending the nascent leading strand, which, upon resetting of the fork back to its original position, will result in bypass of the lesion.…”

mentioning

confidence: 99%