05. Epigenetic regulation of bacterial gene expression (including virulence factors)

Steps in DNA Methylation Regulating Replication Initiation

DnaA binds fully methylated GATC at oriC → After replication, GATC is hemi-methylated → SeqA binds, blocking full methylation → SeqA dissociates → Dam methylates GATC → DnaA re-binds, initiating new replication.

Steps in DNA Methylation Directing DNA Mismatch Repair

After replication, new DNA is hemi-methylated → Mismatch repair system (MutSLH) detects mutation → Non-methylated (new) strand is removed and re-synthesized → Dam methylates the new strand, fully methylating GATC sites.

Steps in DNA Methylation's Role in Genome Defence

Bacteria methylate specific sequences on their DNA to recognize self → Produce restriction enzymes to cut unmodified foreign DNA → Protects against foreign DNA, such as phage.

Steps in DNA Methylation's Role in Gene Regulation

Dam methylates GATC sites → Methylation or regulatory protein binding controls gene expression → New DNA is hemi-methylated → Competition between Dam and regulatory proteins determines methylation status, influencing protein binding and gene regulation.

Epigenetic Control of Gene Expression

Regulation of gene expression through modifications like DNA methylation, which can either activate or silence genes without changing the DNA sequence itself.