Methylation-dependent DNA restriction in Bacillus anthracis

► Bacillus anthracis is poorly transformed by DNA methylated on adenine or cytosine. ► We inactivated three genes encoding methylation-dependent restriction enzymes. ► The resulting strains showed increased transformation by methylated DNA. ► The genes mrr, mcrBP, and mcrB3P each contribute to the restriction of cytosine-methylated DNA. ► Adenine methylation may cause inefficient replication of hemimethylated plasmid DNA.