The Escherichia coli rep Gene

Abstract

The Escherichia coli rep mutant was originally isolated from cells surviving infection with bacteriophage ϕ X174 on the basis of its ability to adsorb ϕ X phage but not to support phage reproduction (Denhardt et al. 1967). This was one of the first deliberate isolations of an E. coli mutant that had lost the capacity to support replication of a virus for reasons other than the loss of an adsorption site. Only one of the original three isolates behaved well; it was designated rep 3 and has been used in much of the subsequent research. The mutant grows well and is not conditionally lethal. It supports the conversion of viral single-stranded (SS) DNA to the double-stranded replicative form (RF), but replication of the RF does not occur. Also, the mutant is altered slightly in its ability to perform cellular recombination and repair activities (Denhardt et al. 1967Denhardt et al. 1972; Calendar et al. 1970). The rep gene maps at 83 minutes, between ilv and metE , and the mutant allele is recessive to the wild-type allele (Calendar et al. 1970). The mutation transduces with ilv at a high frequency, 70–80%, and thus can be easily transferred to other strains. The origin of replication of the E. coli chromosome is located in the same region as the rep gene. Other genes that map in the ilv region are bfm , rho , cya , uvrD , and dnaP (Bachmann et al. 1976). E. coli bfm mutants were isolated as survivors of infection by bacteriophage BF23 that had lost the capacity...