Article révisé par les pairs
| Résumé : | In previous reports, we have described our experiments which suggested a plausible interpretation as to why E. coli dam- mutants, deficient in biological adenine methylation in GATC sequences, are mutators and hyper-recombinators. Based on the study of the progeny of heteroduplex DNA molecules, constructed in vitro by annealing denatured phase λ DNA strands, we concluded that the mistakes made by DNA replication machinery are corrected by mismatch repair occurring preferentially on the new strands. Hence, there is a discrimination between the parental DNA strand (master) and the newly synthesized strand (copy) based on transitory undermethylation of the latter. Mutants deficient in mismatch repair have been isolated in this laboratory, and working hypotheses have been proposed to account for genetic instability of these and dam- mutants. |
