PMID:783136

Citation	Gayda, RC, Yamamoto, LT and Markovitz, A (1976) Second-site mutations in capR (lon) strains of Escherichia coli K-12 that prevent radiation sensitivity and allow bacteriophage lambda to lysogenize.J. Bacteriol. 127:1208-16
Abstract	capR (lon) mutants of Escherichia coli K-12 are mucoid and sensitive to ultraviolet (UV) and X-ray radiation as well as to nitrofurantoin. The mutants form filaments after exposure to these agents. capR mutants are also conditionally lethal since they die when plated on complex medium even without UV treatment; this phenomenon is designated "complex medium-induced killing". Furthermore, capR mutants are poorly lysogenized by bacteriophage lambda. Second-site revertants were isolated by plating on media containing nitrofurantoin. All 17 of the independent revertants studied were still mucoid but resistant to UV radiation. Sixteen of the 17 revertants contained a mutation, sulA, that cotransduced with pyrD (21 min). A second locus, sulB, was also found that cotransduced with leu (2 min). Studies with partial diploids (F'pyrD+ sulA+/pyrD36 sulA17 capR9 (lon) demonstrated that sulA+ is dominant to sulA; thus the indicated partial diploid is UV sensitive, whereas the haploid parent is UV resistant. Furthermore, two other phenotypic traits of capR (lon) mutants were reversed by the sul mutation:complex medium-induced killing and the inability of lambda phage to efficiently lysogenize capR strains. On the basis of these and other results, the following model is suggested to explain capR (lon) and sul gene interactions. capR (lon) is a regulator gene for the structural genes sulA+ and sulB+. Depression of both sul operons results in UV sensitivity and decreased ability of lambda to lysogenize, whereas inactivation of either sul+ protein by mutation to sul prevents these phenomena.
Links	PubMed
Keywords	Chromosome Mapping; Chromosomes, Bacterial; Coliphages; Culture Media; Escherichia coli; Genes; Genes, Regulator; Lysogeny; Mutation; Operon; Transduction, Genetic; Ultraviolet Rays
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Phenotype of	Taxon Information	Genotype Information (if known)	Condition Information	OMP ID	OMP Term Name	ECO ID	ECO Term Name	Notes	Status
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: RGC103 NCBI Taxon ID: 83333	Genotype of Reference Strain: capR9 sulA+ Genotype of Experimental Strain : capR9 sulA	Reference Condition:			0000033	traceable author statement	capR9 sulA mutants developed resistance to UV irradiation. See page 1210 of article.
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