Signal strains that can detect certain DNA replication and membrane mutants of Escherichia coli: Isolation of a new ssb allele, ssb-3

Journal Article · Wed Aug 01 04:00:00 EDT 1990 · Journal of Bacteriology; (USA)

OSTI ID:6790223

Schmellik-Sandage, C S; Tessman, E S ^[1]

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1. Purdue Univ., West Lafayette, IN (USA)

Mutations in several dna genes of Escherichia coli, when introduced into a strain with a lac fusion in the SOS gene sulA, resulted in formation of blue colonies on plates containing 5-bromo-4-chloro-3-indolyl-beta-D-galactoside (X-Gal). Unexpectedly, several lines of evidence indicated that the blue colony color was not primarily due to induction of the SOS system but rather was due to a membrane defect, along with the replication defect, making the cell X-Gal extrasensitive (phenotypically Xgx), possibly because of enhanced permeability to X-Gal or leakage of beta-galactosidase. (i) In most cases, beta-galactosidase specific activity increased only two- to threefold. (ii) Mutations conferring tolerance to colicin E1 resulted in blue colony color with no increase in beta-galactosidase specific activity. (iii) Mutations in either the dnaA, dnaB, dnaC, dnaE, dnaG, or ssb gene, when introduced into a strain containing a bioA::lac fusion, produced a blue colony color without an increase in beta-galactosidase synthesis. These lac fusion strains can serve as signal strains to detect dna mutations as well as membrane mutations. By localized mutagenesis of the 92-min region of the chromosome of the sulA::lac signal strain and picking blue colonies, we isolated a novel ssb allele that confers the same extreme UV sensitivity as a delta recA allele, which is a considerably greater sensitivity than that conferred by the two well-studied ssb alleles, ssb-1 and ssb-113. The technique also yielded dnaB mutants; fortuitously, uvrA mutants were also found.

• OSTI ID: 6790223
• Journal Information: Journal of Bacteriology; (USA), Journal Name: Journal of Bacteriology; (USA) Vol. 172:8; ISSN JOBAA; ISSN 0021-9193
• Country of Publication: United States
• Language: English

Related Subjects

560130* -- Radiation Effects on Microorganisms
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIA
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CHROMOSOMES
DNA REPAIR
DNA REPLICATION
DOSE-RESPONSE RELATIONSHIPS
ELECTROMAGNETIC RADIATION
ENZYME ACTIVITY
ENZYMES
ESCHERICHIA COLI
GALACTOSIDASE
GENE MUTATIONS
GENES
GENOTYPE
GLYCOSYL HYDROLASES
HYDROLASES
MICROORGANISMS
MUTAGENESIS
MUTATIONS
NUCLEIC ACID REPLICATION
O-GLYCOSYL HYDROLASES
RADIATIONS
RADIOINDUCTION
RADIOSENSITIVITY
RECOVERY
REPAIR
ULTRAVIOLET RADIATION