The pi-Histidine Factor of
            <i>Salmonella typhimurium:</i>
            a Demonstration that pi-Histidine Factor Integrates into the Chromosome

Levinthal, Mark; Yeh, Jen Jen

doi:10.1128/jb.109.3.993-1000.1972

Cited by 9 publications

(3 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A deletion may not be required to maintain an E. coli exogenote in hybrids with S. typhimurium, however, since hybrid TC10-29 was selected from a point mutation. Duplicated integrations are known to be phenotypically unstable in E. coli (SOLL and BERG 1969;FOLK and BERG 1971;LEVINTHAL and YEH 1972). Instability in Class V hybrids is probably not due to duplicated integrations which would produce homology patterns different from the female parent.…”

Section: Discussionmentioning

confidence: 99%

“…Of the original group of 58 hybrids, the tests in Tables 2 and 3 assign 15 to Class I, 7 to Class 11, 10 to Class 111, 13 to Class IV, and 12 to Class V. Class I hybrids are exact recombinants; hybrids of Classes 11, I11 and IV are merodiploids with the selected male genes integrated at novel sites (RAVIN and TAKAHASHI 1970), and in Class V hybrids the male genes are present as an exogenote (BARON et al 1968;BARON 1969). The inconsistent behavior of the unclassified hybrid, TC10-38 (phenotypic instability, absence of cryptic trp allele and different homology patterns), can best be explained as due to a duplication integration similar, perhaps, to the pi factor in S. typhimurium (LEVINTHAL and YEH 1972).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

SALMONELLA TYPHIMURIUM-ESCHERICHIA COLI HYBRIDS FOR THE TRYPTOPHAN REGION

Mojica-A

Middleton

1972

Genetics

View full text Add to dashboard Cite

Fifty-eight hybrids were analyzed for their phenotypic stability, presence and nature of cryptic trp alleles and by P22-mediated transduction to yield percent homologies. The hybrids fall into 5 distinguishable classes: a haploid class in which selected E. coli genes replace equivalent sites in the S. typhimurium chromosome; three merodiploid classes in which the selected E. coli genes are integrated at novel sites in the S. typhimurium chromosome—on the same transducing fragment as the female genes selected against, with or without cryptic damage to a nearby gene, or not on the same transducing fragment; and one class in which recombination has not taken place and the E. coli DNA is presumed to be an exogenote. The homology values are heterogeneous and do not permit an accurate determination of the relative frequency of incorporation of the integrated male genetic material. A further study of 20 hybrids indicates that genetic rearrangements can occur in the hybrids.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

SALMONELLA TYPHIMURIUM-ESCHERICHIA COLI HYBRIDS FOR THE TRYPTOPHAN REGION

Mojica-A

Middleton

1972

Genetics

View full text Add to dashboard Cite

show abstract

“…Genetic duplications have been reported for several regions of the bacterial chromosome in Escherichia coli (4, 6-8, 10-14, 22, 24-26) and Salmonella typhimurium (1,2,19,21,27,28). In most cases, the duplicated segments are believed to be arranged in tandem, although several examples of translocation (insertion) duplications have been reported (4,10,14), and in one case the duplicated segment is carried by a plasmid (1,19). The size of duplications varies from as little as one known gene (8,22) to approximately one-third the bacterial chromosome (26).…”

mentioning

confidence: 99%

Genetic and Segregation Analysis of Escherichia coli Strains Containing a Tandem Duplication of the trpD-purB Region of the Chromosome

1978

View full text Add to dashboard Cite

Genetic and segregation analysis of Escherichia coli strains containing a partial duplication of the tip operon reveal that the 2.5-min-long region trpD-purB is duplicated in tandem in the chromosome. The adjacent loci cysB and fabD are not duplicated. Although one copy of the duplicated region is longer than the maximum size of bacteriophage Plkc transducing fragments, the frequency at which the duplicated segment trpDCBA is transferred by transduction to tonBtip deletion strains is equal to that observed for transfer of the normal trp operon. This suggests that three-point recombination events believed to account for transduction of long duplications occur as frequently as two-point recombination events believed to account for normal transduction. Cotransduction frequencies of trpDCBA with the duplicated loci tonB, galU, tyrT, and hemA are very similar to those for the trp operon with the same loci. This indicates that normal genetic linkage is maintained during the three-point recombination event. However, purB, which is normally unlinked to trp by transduction, is closely linked to trpDCBA and thus must be near the repeat point of the duplication. Transduction tests with point mutations in the trp operon indicated that the repeat point occurs near the normal boundary between trpE and trpD. Segregation analysis of heterogenotes constructed from tonB-trp deletion strains shows that the frequency at which a marker is lost is approximately proportional to its distance from the repeat point. This finding is consistent with a random, singlesite crossover event during segregation. Several observations indicate that nonreciprocal genetic exchange also occurs between copies of the duplication. Analysis of heterogenotes containing dadRI and dadR+ demonstrate that the mutant allele is transdominant.

show abstract

Re-initiation of tryptophan operon expression in a promoter deletion strain of Salmonella typhimurium

Fulcher

Bauerle

1978

Molec. Gen. Genet.

View full text Add to dashboard Cite

A genetic and enzymological study was made of five spontaneous prototrophic revertants of a tryptophan auxotroph of Salmonella typhimurium which carries a deletion extending from the closely linked supX locus into the trp operator-promoter region. The revertants were found to have regained initiation of expression of all five trp genes. Recombinational tests showed that in each case the genetic change responsible for re-initiation is cotransducible with the trp-cysB region of the chromosome. Two different mechanisms leading to re-initiation of trp gene expression were established: (a) an extension of the limits of the original deletion resulting in the fusion of the trp structural genes with a nearby gene or gene set located outside the operator end of trp, and (b) translocation of a duplicate set of the trp structural genes to other chromosomal sites, located operator-distal to the normal trp operon, in such a manner that they are functionally fused to foreign genetic units. One revertant which arose by mechanism (a) was shown to have an extended deletion with one new terminus in trp and the other in the nearby cysB locus. All the revertants exhibit constitutive expression of the trp enzymes, with activities varying among strains from five to forty five times greater than the fully repressed wild type level. The protein product of trpA, the first structural gene of the operon, appears to have been partially damaged by the re-initiation event in at least two strains, while in the other strains, the enzyme appears in preliminary tests to be indistinguishable from that of wild type.

show abstract

The pi-Histidine Factor of Salmonella typhimurium: a Demonstration that pi-Histidine Factor Integrates into the Chromosome

Cited by 9 publications

References 16 publications

SALMONELLA TYPHIMURIUM-ESCHERICHIA COLI HYBRIDS FOR THE TRYPTOPHAN REGION

SALMONELLA TYPHIMURIUM-ESCHERICHIA COLI HYBRIDS FOR THE TRYPTOPHAN REGION

Genetic and Segregation Analysis of Escherichia coli Strains Containing a Tandem Duplication of the trpD-purB Region of the Chromosome

Re-initiation of tryptophan operon expression in a promoter deletion strain of Salmonella typhimurium

Contact Info

Product

Resources

About