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 |
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| 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. |
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| Keywords |
Chromosome Mapping; Chromosomes, Bacterial; Coliphages; Culture Media; Escherichia coli; Genes; Genes, Regulator; Lysogeny; Mutation; Operon; Transduction, Genetic; Ultraviolet Rays |
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Main Points of the Paper
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Materials and Methods Used
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Phenotype Annotations
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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 |
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a mutation or genetic difference within a strain |
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capR9 sulA mutants developed resistance to UV irradiation. See page 1210 of article. |
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a mutation or genetic difference within a strain |
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0000033 |
traceable author statement |
capR9 sulA mutants were mucoid on medium agar. See page 1210 of article. |
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a mutation or genetic difference within a strain |
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sulA mutation caused homogeneity in cell production, specifically the production of short rods in complex medium. See figure 1D. |
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a mutation or genetic difference within a strain |
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sulA mutation prevented the loss of growth viability in complex medium. See table 4 for full results on Complex medium induced killing. |
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a mutation or genetic difference within a strain |
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sul mutation prevent the proliferation of lethal filamentation caused by complex medium. |
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a mutation or genetic difference within a strain |
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sulA mutation confers the ablity for lambda to lysogenize at normal efficiency. see table 5 for full exprimental results. |
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Notes
- sulA mutation was linked with pyrD (21 min).
- sulB mutation was linked with leu (2 min).
- unirradiated capR(lon) cells grown in complex broth are a mixture of short, normal and filamentous cells. See figure 1b on page 1212.
References
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