Corynebacterium glutamicum DNA is subjected to methylation-restriction in Escherichia coli

Efficient electroporation of Escherichia coli with plasmid DNA isolated from Corynebacterium glutamicum depends on the use of Mcr-deficient E. coli strains. The transformation frequency increased nearly 800-fold when the Mcr-deficient E. coli DH5 alpha MCR was used instead of E. coli DH5 alpha. We used E. coli strains with different mutations in the methyl-specific restriction systems to show that McrBC-deficiency is sufficient to generate this effect. The results imply that C. glutamicum DNA contains methylcytosine in specific sequences recognized by the E. coli McrBC system.