A bacterial defense system targeting modified cytosine of phage genomic DNA.

ABSTRACT: The evolutionary arms race between bacteria and phages drives the development of bacterial antiviral defense systems and phage counter-defense strategies. Restriction-modification (RM) systems protect bacteria by methylating 'self' DNA and cleaving unmodified phage DNA. Phages like T-even coliphages evade RM systems by substituting cytosine with 5-hydroxymethyl cytosine (5hmC) or 5-glucosylated hmC (5ghmC). Here, we characterize ‌a single-component antiviral defense system featuring a GIY-YIG endonuclease domain. Biochemical and structural analyses demonstrate that this defense system is a type IV modification-dependent restriction endonuclease that specifically degrades 5hmC- or 5ghmC-modified DNA, and we accordingly name it CMoRE (Cytosine Modification ‌R‌estriction Endonuclease). The cr

SUBMITTER: Liu R 

PROVIDER: S-EPMC12923530 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature