AUTHOR=Wu Dongqing , Wang Yali , Xu Xudong 

TITLE=Effects of a Type I RM System on Gene Expression and Glycogen Catabolism in Synechocystis sp. PCC 6803

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01258

DOI=10.3389/fmicb.2020.01258

ISSN=1664-302X

ABSTRACT=<p>Increasing evidence has shown that DNA methylation is involved in gene regulation in prokaryotes. However, there have been very limited reports about the role of DNA methylation in regulation of gene expression and physiological functions in cyanobacteria. In <italic>Synechocystis</italic> sp. PCC 6803, four genes on the plasmid pSYSX are predicted to encode the type I restriction-methylation system, <italic>slr6095</italic> and <italic>slr6096</italic> for the M subunit, <italic>slr6097</italic> for the S subunit and <italic>slr6102</italic> for the <italic>R</italic> subunit. Compared to the wild type, <italic>slr6095</italic>, <italic>slr6096</italic>, and <italic>slr6097</italic> mutants lacked the GG<sup>m6</sup>AN<sub>7</sub>TTGG/CCA<sup>m6</sup>AN<sub>7</sub>TCC methylation in genomic DNA. Transcriptomic analysis indicated that 171 genes were reproducibly up- or down-regulated in all three mutants relative to the wild type. The changed expression of some genes, including <italic>sll1356</italic> for glycogen phosphorylase (GlgP), was associated with the loss of GG<sup>m6</sup>AN<sub>7</sub>TTGG/CCA<sup>m6</sup>AN<sub>7</sub>TCC methylation in the coding regions or the upstream non-coding sequences. Inactivation of <italic>slr6095</italic>, <italic>slr6096</italic>, or <italic>slr6097</italic> increased the expression of <italic>sll1356</italic> and the GlgP activity but lowered the glycogen content. These results indicated that the DNA methylation by a type I RM system could alter the expression of certain genes and physiological functions in <italic>Synechocystis</italic> sp. PCC 6803.</p>