Sex hair (F-pili) mutants of E. coli

Silverman, P.; Mobach, Helen Wedel; Valentine, Raymond C.

doi:10.1016/s0006-291x(67)80115-3

Cited by 27 publications

(12 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this communication we report a method to isolate such mutants and the phenotypic characterization of one class of them. These methods were essentially as described (21,22), except that the concentration of N-methyl-N'-nitro-N-nitrosoguanidine was 8 jg/ml. Under these conditions survival of the recA strain AE3087 (see Table 1) was about 1%.…”

mentioning

confidence: 99%

Chromosomal mutations of Escherichia coli that alter expression of conjugative plasmid functions.

McEwen¹,

Silverman²

1980

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

We have identified two chromosomal genes of Escherichia coli K12 that are required for the expression of conjugative plasmid functions in the presence of normal plasmid DNA. Hfr cells with mutations in both of these genes are resistant to donor-specific bacteriophage and defective as conjugal donors. These characteristics can be attributed to the inability of mutant Hfr cells to elaborate F-pili, surface organelles required both for conjugal donor ability and for sensitivity to donor-specific bacteriophages. Mutant cels are also defective in surface exclusion, the property of donor cells to act as poor conjugal recipients. This defect can be attributed in part to a reduction in the amount of the F-plasmid traTgene product in the outer membrane of mutant cells; this protein is one of two plasmid gene products required for the full expression of surface exclusion. We have designated the chromosomal genes identified by these mutations as cpxA and cpxB; the mnemonic cpx signifying conjugative plasmid expression.

show abstract

mentioning

confidence: 99%

Chromosomal mutations of Escherichia coli that alter expression of conjugative plasmid functions.

McEwen¹,

Silverman²

1980

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…TYE was tryptone-yeast extract-calcium medium (11). EMB-O agar was as described by Silverman, Mobach, and Valentine (19).…”

mentioning

confidence: 99%

“…(ii) f2-Resistant mutants. Rapid screening for f2 resistance was accomplished by a variation of the EMB technique reported by Silverman, Mobach, and Valentine (19). A loopful of an f2 lysate (about 5 x 1011 phage/ml) was streaked in a line across the center of an EMB-O plate and allowed to soak in.…”

mentioning

confidence: 99%

Deletion Map of the Escherichia coli K-12 Sex Factor F: the Order of Eleven Transfer Cistrons

1972

View full text Add to dashboard Cite

A series of Hfr deletion mutants was isolated. These mutants contain deletions which extend from a A prophage into an Flac which is integrated into the gal operon. Transfer-deficient deletion mutants were found to fall into four different phenotypic groups when tested for maleand female-specific phage resistance. Conjugational and transductional complementation tests with Flac point mutants deficient in transfer (tra-) were performed, and the order of 11 tra cistrons was determined. The tra genes are all located between an F gene for the inhibition of female-specific phages and the transposed lac operon originally carried by the Flac. The order of genes in the Hfr studied was established to be: proC .

show abstract

“…The differences between these groups, in particular the antigenic differences, which imply differences in the conformation ofthe coat proteins, suggest that the adsorption specificities of the phages might not be identical. Silverman, Mobach & Valentine (1967) Two RNA phages infecting Pseudomonas aeruqginosa have been reported (Feary, Fisher & Fisher, 1963;Bradley, 1966). These are very closely related (D. E. Bradley, personal communication).…”

Section: Introductionmentioning

confidence: 99%