AUTHOR=Sheng Duo-Hong , Wang Yi-Xue , Qiu Miao , Zhao Jin-Yi , Yue Xin-Jing , Li Yue-Zhong 

TITLE=Functional Division Between the RecA1 and RecA2 Proteins in Myxococcus xanthus

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00140

DOI=10.3389/fmicb.2020.00140

ISSN=1664-302X

ABSTRACT=<p><italic>Myxococcus xanthus</italic> DK1622 has two RecA genes, <italic>recA1</italic> (MXAN_1441) and <italic>recA2</italic> (MXAN_1388), with unknown functional differentiation. Herein, we showed that both <italic>recA</italic> genes were induced by ultraviolet (UV) irradiation but that the induction of <italic>recA1</italic> was more delayed than that of <italic>recA2</italic>. Deletion of <italic>recA1</italic> did not affect the growth but significantly decreased the UV-radiation survival, homologous recombination (HR) ability, and induction of LexA-dependent SOS genes. In contrast, the deletion of <italic>recA2</italic> markedly prolonged the lag phase of bacterial growth and increased the sensitivity to DNA damage caused by hydrogen peroxide but did not change the UV-radiation resistance or SOS gene inducibility. Protein activity analysis demonstrated that RecA1, but not RecA2, catalyzed DNA strand exchange (DSE) and LexA autocleavage <italic>in vitro</italic>. Transcriptomic analysis indicated that RecA2 has evolved mainly to regulate gene expression for cellular transportation and antioxidation. This is the first report of functional divergence of duplicated bacterial <italic>recA</italic> genes. The results highlight the evolutionary strategy of <italic>M. xanthus</italic> cells for DNA HR and genome sophistication.</p>