Chromosomal directionality of DNA mismatch repair in
            <i>Escherichia coli</i>

Hasan, A M Mahedi; Leach, David R. F.

doi:10.1073/pnas.1505370112

Cited by 12 publications

(22 citation statements)

References 52 publications

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“…This is supported by recent in vivo data indicating that the GATC site distribution influences repair efficiency through determining excision tract length rather than through influencing the efficiency of strand incision (42). …”

Section: Discussionsupporting

confidence: 62%

Dual daughter strand incision is processive and increases the efficiency of DNA mismatch repair

et al. 2016

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DNA mismatch repair (MMR) is an evolutionarily-conserved process responsible for the repair of replication errors. In Escherichia coli, MMR is initiated by MutS and MutL, which activate MutH to incise transiently-hemimethylated GATC sites. MMR efficiency depends on the distribution of these GATC sites. To understand which molecular events determine repair efficiency, we quantitatively studied the effect of strand incision on unwinding and excision activity. The distance between mismatch and GATC site did not influence the strand incision rate, and an increase in the number of sites enhanced incision only to a minor extent. Two GATC sites were incised by the same activated MMR complex in a processive manner, with MutS, the closed form of MutL and MutH displaying different roles. Unwinding and strand excision were more efficient on a substrate with two nicks flanking the mismatch, as compared to substrates containing a single nick or two nicks on the same side of the mismatch. Introduction of multiple nicks by the human MutLα endonuclease also contributed to increased repair efficiency. Our data support a general model of prokaryotic and eukaryotic MMR in which, despite mechanistic differences, mismatch-activated complexes facilitate efficient repair by creating multiple daughter strand nicks.

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Section: Discussionsupporting

confidence: 62%

Dual daughter strand incision is processive and increases the efficiency of DNA mismatch repair

et al. 2016

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“…The mutation spectrum in the uvrAdinBmutS strain is essentially comparable to that in the uvrAdinB strain, with perhaps a slight overall increase ($2-fold). The modest correction efficiency by MMR may reflect that, here, we monitor errors made by Pol V in the context of a gap-filling reaction rather than at a replication fork as previously noted (Hasan and Leach, 2015;Simmons et al, 2008). Lack of efficient MMR correction of Pol z errors has previ-ously been reported in yeast (Aksenova et al, 2010;Lehner and Jinks-Robertson, 2009).…”

Section: Untargeted Base Substitution Mutations: Putative Involvementmentioning

confidence: 76%

Pol V-Mediated Translesion Synthesis Elicits Localized Untargeted Mutagenesis during Post-replicative Gap Repair

Isogawa¹,

Ong²,

Потапов³

et al. 2018

Cell Reports

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In vivo, replication forks proceed beyond replication-blocking lesions by way of downstream repriming, generating daughter strand gaps that are subsequently processed by post-replicative repair pathways such as homologous recombination and translesion synthesis (TLS). The way these gaps are filled during TLS is presently unknown. The structure of gap repair synthesis was assessed by sequencing large collections of single DNA molecules that underwent specific TLS events in vivo. The higher error frequency of specialized relative to replicative polymerases allowed us to visualize gap-filling events at high resolution. Unexpectedly, the data reveal that a specialized polymerase, Pol V, synthesizes stretches of DNA both upstream and downstream of a site-specific DNA lesion. Pol V-mediated untargeted mutations are thus spread over several hundred nucleotides, strongly eliciting genetic instability on either side of a given lesion. Consequently, post-replicative gap repair may be a source of untargeted mutations critical for gene diversification in adaptation and evolution.

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“…This differential efficiency of Beta-mediated LT213 recombinants is indicative of heteroduplex plasmid recombination intermediates that form in the absence of DNA replication and that can be subsequently repaired in the Mut + host when the plasmid is replicated. Methyl-directed MMR of the newly replicated, unmethylated DNA strand is coupled to DNA replication ( 46 ). For RecT, we found that the apparent recombination efficiency of oligonucleotide LT213 was ~6-fold lower in a Mut + host than in a mutS mutant host (see Table S3 ).…”

Section: Resultsmentioning

confidence: 99%

Examining a DNA Replication Requirement for Bacteriophage λ Red- and Rac Prophage RecET-Promoted Recombination in Escherichia coli

Thomason

Costantino

Court

2016

mBio

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Recombineering, in vivo genetic engineering with bacteriophage homologous recombination systems, is a powerful technique for making genetic modifications in bacteria. Two systems widely used in Escherichia coli are the Red system from phage λ and RecET from the defective Rac prophage. We investigated the in vivo dependence of recombineering on DNA replication of the recombining substrate using plasmid targets. For λ Red recombination, when DNA replication of a circular target plasmid is prevented, recombination with single-stranded DNA oligonucleotides is greatly reduced compared to that under replicating conditions. For RecET recombination, when DNA replication of the targeted plasmid is prevented, the recombination frequency is also reduced, to a level identical to that seen for the Red system in the absence of replication. The very low level of oligonucleotide recombination observed in the absence of any phage recombination functions is the same in the presence or absence of DNA replication. In contrast, both the Red and RecET systems recombine a nonreplicating linear dimer plasmid with high efficiency to yield a circular monomer. Therefore, the DNA replication requirement is substrate dependent. Our data are consistent with recombination by both the Red and RecET systems occurring predominately by single-strand annealing rather than by strand invasion.

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Chromosomal directionality of DNA mismatch repair in Escherichia coli

Cited by 12 publications

References 52 publications

Dual daughter strand incision is processive and increases the efficiency of DNA mismatch repair

Dual daughter strand incision is processive and increases the efficiency of DNA mismatch repair

Pol V-Mediated Translesion Synthesis Elicits Localized Untargeted Mutagenesis during Post-replicative Gap Repair

Examining a DNA Replication Requirement for Bacteriophage λ Red- and Rac Prophage RecET-Promoted Recombination in Escherichia coli

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