Fine-Structure Map of the Histidine Transport Genes in \u3cem\u3eSalmonella typhimurium\u3c/em\u3e

Afine-structure genetic map of the histidine transport region of the Salmonella typhimurium chromosome was constructed. Twenty-five deletion mutants were isolated and used for dividing the hisJ and hisP genes into 8 and 13 regions respectively. A total of 308 mutations, spontaneous and mutagen induced, have been placed in these regions by deletion mapping. The histidine transport operon is presumed to be constituted of genes dhuA, hisJ, and hisP, and the regulation of the hosP and hisJ genes by dhuA is discussed. The orientation of this operon relative to purF has been established by three-point crosses as being: purF duhA hisJ hisP

Evidence for a Common Mechanism for the Insertion of the Tn10 Transposon and for the Generation of Tn10-stimulated Deletions

Mutations in and near the Salmonella typhimurium histidine transport operon were generated by insertion of the translocatable tetracycline-resistance element Tn10. Deletion mutants affecting histidine transport genes were subsequently isolated in several of the Tn10-containing strains. Tn10 insertions in hisJ occurred preferentially at one site, designated site A. This same site was also the preferential endpoint of deletions originating from Tn10 insertions at two neighboring sites. Thus, Tn10 insertion and Tn10-stimulated deletion formation appear to involve a common DNA-recogition step

Hydrophobic Chromatography in the Purification of the Histidine-binding Protein J from \u3cem\u3eSalmonella typhimurium\u3c/em\u3e

Upon increasing the length of the side chains in a homologous series of ω-aminoalkyl agaroses (Seph—Cn—NH2), more and more proteins become adsorbed onto the column and it is thus possible to achieve purification by selective exclusion of a desired protein. This principle is illustrated in the purification of the histidine-binding protein j from Salmonella typhimurium, vising ω-aminodecyl or ω-aminododecyl agarose columns. The protein was purified 7- to 10-fold in one step from either the shock fluid or the crude extract of the bacteria. Since protein j has an isoelectric pH of 5.5 and yet does not bind to the positively charged columns at pH 7, it seems that this protein is not likely to have available hydrophobic pockets and may thus be remarkably hydrophilic, compared with the other proteins in the shock fluid

A Single Amino Acid Substitution in a Histidine-Transport Protein Drastically Alters its Mobility in Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis

Mutation hisJ5625 has altered the histidine-binding protein J of Salmonella typhimurium such that histidine transport is impaired, even though binding of histidine by the J protein is unimpaired. We have determined by protein analytical methods that the only effect of this mutation has been the substitution of a cysteine residue for an arginine at a site in the interior of the polypeptide chain. This arginine residue is therefore potentially essential for the transport function of the protein. The mutant protein migrates in sodium dodecyl sulfate-polyacrylamide gel electrophoresis more slowly than the wild type protein, as if its molecular weight were greater by as much as 2000. Since this behavior is apparently due to a single amino acid replacement, a molecular weight difference even between two closely related proteins should not be inferred solely on the basis of sodium dodecyl sulfate gel electrophoresis

Nitrogen regulation of transport operons: analysis of promoters argTr and dhuA

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