AUTHOR=Park Hye-Jee , Seong Hoon Je , Lee Jongchan , Heo Lynn , Sul Woo Jun , Han Sang-Wook 

TITLE=Two DNA Methyltransferases for Site-Specific 6mA and 5mC DNA Modification in Xanthomonas euvesicatoria

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.621466

DOI=10.3389/fpls.2021.621466

ISSN=1664-462X

ABSTRACT=<p><italic>Xanthomonas euvesicatoria</italic> (<italic>Xe</italic>) is a gram-negative phytopathogenic bacterium that causes bacterial spot disease in tomato/pepper leading to economic losses in plantations. DNA methyltransferases (MTases) are critical for the survival of prokaryotes; however, their functions in phytopathogenic bacteria remain unclear. In this study, we characterized the functions of two putative DNA MTases, XvDMT1 and XvDMT2, in <italic>Xe</italic> by generating XvDMT1- and XvDMT2-overexpressing strains, <italic>Xe</italic>(XvDMT1) and <italic>Xe</italic>(XvDMT2), respectively. Virulence of <italic>Xe</italic>(XvDMT2), but not <italic>Xe</italic>(XvDMT1), on tomato was dramatically reduced. To postulate the biological processes involving XvDMTs, we performed a label-free shotgun comparative proteomic analysis, and results suggest that XvDMT1 and XvDMT2 have distinct roles in <italic>Xe</italic>. We further characterized the functions of XvDMTs using diverse phenotypic assays. Notably, both <italic>Xe</italic>(XvDMT1) and <italic>Xe</italic>(XvDMT2) showed growth retardation in the presence of sucrose and fructose as the sole carbon source, with <italic>Xe</italic>(XvDMT2) being the most severely affected. In addition, biofilm formation and production of exopolysaccharides were declined in <italic>Xe</italic>(XvDMT2), but not <italic>Xe</italic>(XvDMT1). <italic>Xe</italic>(XvDMT2) was more tolerant to EtOH than <italic>Xe</italic>(XvDMT1), which had enhanced tolerance to sorbitol but decreased tolerance to polymyxin B. Using single-molecule real-time sequencing and methylation-sensitive restriction enzymes, we successfully predicted putative motifs methylated by XvDMT1 and XvDMT2, which are previously uncharacterized 6mA and 5mC DNA MTases, respectively. This study provided new insights into the biological functions of DNA MTases in prokaryotic organisms.</p>