| 论文摘要： |
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. InSynechocystissp. PCC 6803, four genes on the plasmid pSYSX are predicted to encode the type I restriction-methylation system,slr6095andslr6096for the M subunit,slr6097for the S subunit andslr6102for theRsubunit. Compared to the wild type,slr6095,slr6096, andslr6097mutants lacked the GG(m6)AN(7)TTGG/CCA(m6)AN(7)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, includingsll1356for glycogen phosphorylase (GlgP), was associated with the loss of GG(m6)AN(7)TTGG/CCA(m6)AN(7)TCC methylation in the coding regions or the upstream non-coding sequences. Inactivation ofslr6095,slr6096, orslr6097increased the expression ofsll1356and 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 inSynechocystissp. PCC 6803. |
