Type I restriction-modification systems regulate gene expression through DNA topology.

DNA methylation by restriction-modification systems modulates gene expression in bacteria through changes in DNA topology, with effects observed in both Streptococcus pneumoniae and Escherichia coli.

• Why it matters: Understanding how bacteria regulate gene expression is crucial for insights into pathogenicity and adaptation, yet the role of RM system-mediated methylation in this process remains unclear.
• What they did: The study used RNA-seq, luciferase reporter assays, and methylome profiling on pneumococcal and E. coli strains, focusing on methylation effects mediated by HsdM and EcoKI systems across multiple strains.
• The result: Methylation alters DNA topology, reducing negative supercoiling and influencing promoter activity, which enables bacteria to dynamically regulate gene networks epigenetically.