AUTHOR=Romero Hector , Serrano Ester , Hernández-Tamayo Rogelio , Carrasco Begoña , Cárdenas Paula P. , Ayora Silvia , Graumann Peter L. , Alonso Juan C. 

TITLE=Bacillus subtilis RarA Acts as a Positive RecA Accessory Protein

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00092

DOI=10.3389/fmicb.2020.00092

ISSN=1664-302X

ABSTRACT=<p>Ubiquitous RarA AAA<sup>+</sup> ATPases play crucial roles in the cellular response to blocked replication forks in pro- and eukaryotes. Here, we provide evidence that absence of RarA reduced the viability of Δ<italic>recA</italic>, Δ<italic>recO</italic>, and <italic>recF</italic>15 cells during unperturbed growth. The <italic>rarA</italic> gene was epistatic to <italic>recO</italic> and <italic>recF</italic> genes in response to H<sub>2</sub>O<sub>2</sub>- or MMS-induced DNA damage. Conversely, the inactivation of <italic>rarA</italic> partially suppressed the HR defect of mutants lacking end-resection (Δ<italic>addAB</italic>, Δ<italic>recJ</italic>, Δ<italic>recQ</italic>, Δ<italic>recS</italic>) or branch migration (Δ<italic>ruvAB</italic>, Δ<italic>recG</italic>, Δ<italic>radA</italic>) activity. RarA contributes to RecA thread formation, that are thought to be the active forms of RecA during homology search. The absence of RarA reduced RecA accumulation, and the formation of visible RecA threads <italic>in vivo</italic> upon DNA damage. When Δ<italic>rarA</italic> was combined with mutations in genuine RecA accessory genes, RecA accumulation was further reduced in Δ<italic>rarA</italic> Δ<italic>recU</italic> and Δ<italic>rarA</italic> Δ<italic>recX</italic> double mutant cells, and was blocked in Δ<italic>rarA recF</italic>15 cells. These results suggest that RarA contributes to the assembly of RecA nucleoprotein filaments onto single-stranded DNA, and possibly antagonizes RecA filament disassembly.</p>