Methylation Motifs in Promoter Sequences May Contribute to the Maintenance of a Conserved m5 C Methyltransferase in Helicobacter pylori

• Published in: Microorganisms (Basel) Vol. 9; no. 12
• Main Authors: Meng, Bowen, Epp, Naomi, Wijaya, Winsen, Mrázek, Jan, Hoover, Timothy R
• Format: Journal Article
• Language: English
• Published: Switzerland 30.11.2021
• Subjects: Helicobacter pylori; DNA methylation; 5-methylcytosine DNA methyltransferase
• ISSN: 2076-2607

DNA methylomes of strains are complex due to the large number of DNA methyltransferases (MTases) they possess. J99 M.Hpy99III is a 5-methylcytosine ( C) MTase that converts GCGC motifs to G CGC. Homologs of M.Hpy99III are found in essentially all strains. Most of these homologs are orphan MTases that lack a cognate restriction endonuclease, and their retention in strains suggest they have roles in gene regulation. To address this hypothesis, green fluorescent protein (GFP) reporter genes were constructed with six putative promoters that had a GCGC motif in the extended -10 region, and the expression of the reporter genes was compared in wild-type G27 and a mutant lacking the M.Hpy99III homolog (M.HpyGIII). The expression of three of the GFP reporter genes was decreased significantly in the mutant lacking M.HpyGIII. In addition, the growth rate of the G27 mutant lacking M.HpyGIII was reduced markedly compared to that of the wild type. These findings suggest that the methylation of the GCGC motif in many GCGC-containing promoters is required for the robust expression of genes controlled by these promoters, which may account for the universal retention of M.Hpy99III homologs in strains.