DNA cytosine methyltransferase enhances viability during prolonged stationary phase in Escherichia coli

• Published in: FEMS microbiology letters Vol. 367; no. 20; pp. 1 - 9
• Main Authors: Militello, Kevin T, Finnerty-Haggerty, Lara, Kambhampati, Ooha, Huss, Rebecca, Knapp, Rachel
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 05.11.2020
• Subjects: Bacterial physiology; Catalase; Cytosine; Deoxyribonucleic acid; DNA; DNA methyltransferase; DNA sequencing; E coli; Escherichia coli; Gene expression; Genetic aspects; Methods; Methyltransferases; Microbiology; Nucleotide sequence; Nucleotide sequencing; Phenotypes; Physiological aspects; Restriction-modification; Stationary phase; United States; 5-methylcytosine; stationary phase; Vsr; RpoS; Dcm; orphan DNA methyltransferase
• ISSN: 1574-6968; 0378-1097; 1574-6968
• DOI: 10.1093/femsle/fnaa166

ABSTRACT In Escherichia coli, DNA cytosine methyltransferase (Dcm) methylates the second cytosine in the sequence 5′CCWGG3′ generating 5-methylcytosine. Dcm is not associated with a cognate restriction enzyme, suggesting Dcm impacts facets of bacterial physiology outside of restriction-modification systems. Other than gene expression changes, there are few phenotypes that have been identified in strains with natural or engineered Dcm loss, and thus Dcm function has remained an enigma. Herein, we demonstrate that Dcm does not impact bacterial growth under optimal and selected stress conditions. However, Dcm does impact viability in long-term stationary phase competition experiments. Dcm+ cells outcompete cells lacking dcm under different conditions. Dcm knockout cells have more RpoS-dependent HPII catalase activity than wild-type cells. Thus, the impact of Dcm on stationary phase may involve changes in RpoS activity. Overall, our data reveal a new role for Dcm during long-term stationary phase. Dcm promotes viability during long-term stationary phase and represses RpoS activity.