S. Ankri et al., IMPROVED ELECTROTRANSFORMATION OF HIGHLY DNA-RESTRICTIVE CORYNEBACTERIA WITH DNA EXTRACTED FROM STARVED ESCHERICHIA-COLI, FEMS microbiology letters, 140(2-3), 1996, pp. 247-251
Differences of up to 33 000-fold in electro-transformability of highly
DNA restrictive corynebacteria are observed in the DNA of a shuttle p
lasmid extracted from Escherichia coli hosts propagated in different n
utritional conditions. Growth of the host in minimal medium increases
plasmid transformability, whereas growth on rich media decreases it. I
n the E. coli DH5 alpha. host, the starvation-dependent increase in DN
A transformability is reverted by supplementing with methionine, an ob
ligate S-adenosyl-methionine (SAM) precursor. This suggests that an E.
coli nutritionally modulated SAM-dependent DNA-methyltransferase may
be involved in this phenomenon.