The positioning of Chi sites allows the RecBCD pathway to suppress some genomic rearrangements

TitleThe positioning of Chi sites allows the RecBCD pathway to suppress some genomic rearrangements
Publication TypeJournal Article
Year of Publication2019
AuthorsLi C, Danilowicz C, Tashjian TF, Godoy VG, Prévost C, Prentiss M
JournalNucleic Acids Res
Volume47
Pagination1836-1846
Date Published02
Abstract

Bacterial recombinational repair of double-strand breaks often begins with creation of initiating 3' single-stranded DNA (ssDNA) tails on each side of a double-strand break (DSB). Importantly, if the RecBCD pathway is followed, RecBCD creates a gap between the sequences at 3' ends of the initiating strands. The gap flanks the DSB and extends at least to the nearest Chi site on each strand. Once the initiating strands form ssDNA-RecA filaments, each ssDNA-RecA filament searches for homologous double-stranded DNA (dsDNA) to use as a template for the DNA synthesis needed to fill the gap created by RecBCD. Our experimental results show that the DNA synthesis requires formation of a heteroduplex dsDNA that pairs >20 contiguous bases in the initiating strand with sequence matched bases in a strand from the original dsDNA. To trigger synthesis, the heteroduplex must be near the 3' end of the initiating strand. Those experimentally determined requirements for synthesis combined with the Chi site dependence of the function of RecBCD and the distribution of Chi sites in bacterial genomes could allow the RecBCD pathway to avoid some genomic rearrangements arising from directly induced DSBs; however, the same three factors could promote other rearrangements.

DOI10.1093/nar/gky1252
Citation Key2019|2062
PubMed ID30544167