Identification of a non-haem catalase in Salmonella and its regulation by RpoS (sigmaS).

We report the identification and functional analysis of katN, a gene encoding a non-haem catalase of Salmonella enterica serotype Typhimurium. katN, which is not present in Escherichia coli, is located between the yciGFE and yciD E. coli homologues in the Salmonella genome.

Comparison of the abilities of Salmonella typhimurium rpoS, aroA and rpoS aroA strains to elicit humoral immune responses in BALB/c mice and to cause lethal infection in athymic BALB/c mice.

Salmonella typhimurium rpoS and rpoS aroA mutants are effective live vaccines in the murine model of salmonellosis (Coynault et al., Mol. Microbiol.

Virulence and vaccine potential of Salmonella typhimurium mutants deficient in the expression of the RpoS (sigma S) regulon.

The alternative sigma factor RpoS (sigma S) is required for Salmonella virulence in mice. We report the immunizing capacity of Salmonella typhimurium rpoS and rpoS aroA mutants to protect susceptible BALB/c mice against subsequent oral challenge with virulent S. typhimurium.

The live oral typhoid vaccine Ty21a is a rpoS mutant and is susceptible to various environmental stresses.

The rpoS (katF) gene, which encodes a RNA polymerase sigma factor (sigma s), regulates the virulence of Salmonella typhimurium in mice. In the present study, we show that rpoS mutants can be frequently found among laboratory strains of Salmonella. In addition, a rpoS mutation was identified in the S.

The Salmonella typhimurium katF (rpoS) gene: cloning, nucleotide sequence, and regulation of spvR and spvABCD virulence plasmid genes.

The spv region of Salmonella virulence plasmids is essential for the development of a systemic infection in mice. Transcriptional activation of the spvABCD operon occurs during stationary growth phase and is mediated by the regulatory gene product SpvR. We have previously shown that expression of a spvRAB'-cat fusion in Escherichia coli was dependent on the katF (rpoS) locus which encodes an alternative sigma factor (sigma S).

The putative sigma factor KatF (RpoS) is required for the transcription of the Salmonella typhimurium virulence gene spvB in Escherichia coli.

The virulence of Salmonella typhimurium for mice is dependent on a plasmid-borne gene cluster termed spv. We previously determined that both S. typhimurium and Escherichia coli bacteria grown in a rich medium preferentially express the spv genes during the stationary phase of growth.

Growth phase and SpvR regulation of transcription of Salmonella typhimurium spvABC virulence genes.

The 90 kb virulence plasmid of Salmonella typhimurium is required for bacterial growth beyond the small intestine to deeper tissues such as the spleen and liver of orally inoculated mice. We constructed transcriptional lacZ fusions within the cloned plasmid-borne virulence genes spvA, spvB and spvC of S. typhimurium to demonstrate that spvR encodes a trans-acting positive regulator for the transcription of spvA, spvB and spvC.

Cloning and expression of plasmid DNA sequences involved in Salmonella serotype typhimurium virulence.

A 22kb region of the 90kb virulence-associated plasmid, pIP1350, of Typhimurium strain C52 was cloned into the mobilizable vector pSUP202, yielding plasmid pIP1352. This recombinant plasmid restored full virulence to plasmidless strain C53 in a mouse model. Transposon Tn5 insertion mutagenesis demonstrated the existence of two DNA sequences in pIP1352 designated VirA and VirB, both of which are essential for the expression of virulence.

A new method for the physical and genetic mapping of large plasmids: application to the localisation of the virulence determinants on the 90 kb plasmid of Salmonella typhimurium.

A new method based on transposon-promoted deletions was used to generate a set of deletions in the 90 kb virulence plasmid of Salmonella typhimurium. The analysis of 16 deletion mutants allowed: (1) construction of the restriction map of the plasmid for HindIII, BamHI and BglII; (2) localisation of the plasmid region involved in virulence; (3) identification of two functional replicons on the plasmid.

Virulence-associated plasmids of Salmonella serotype Typhimurium in experimental murine infection.

The growth pattern of Salmonella enterica subsp. enterica serotype Typhimurium (Typhimurium) was studied in mice to examine the role of the 60-Mdal virulence-associated plasmid in the pathogenesis of mouse typhoid. After repeated subcultures at 45 degrees C, isogenic variants harbouring the virulence-associated plasmid (strains C52, TM122 and TM332) or having lost this large plasmid (strains C53, TM123 and TM333) were obtained from three parental strains (strains C5, TM12 and TM33, respectively).

[Taxonomic position of Agrobacterium strains of hospital origin].

A collection of 31 strains received as Agrobacterium tumefaciens and A. radiobacter was subjected to detailed phenotypic and genomic studies. These strains were recovered from plants, soil, water and clinical specimens.

Molecular relationships between virulence plasmids of Salmonella serotypes typhimurium and dublin and large plasmids of other Salmonella serotypes.

All studied isolates of Salmonella serotypes abortusovis (16 strains), enteritidis (30 strains), paratyphi C (29 strains), and 2 out of 10 isolates of serotype newport harboured large 54-76-Kb plasmids. No such plasmids were found in the following serotypes: agona, bovismorbificans, heidelberg, infantis, panama, paratyphi A, paratyphi B, saintpaul, senftenberg and typhi. These plasmids and the virulence-associated plasmids of Salmonella serotypes typhimurium and dublin were compared at the molecular level.

Use of DEAE-cellulose filters in the S1 nuclease method for bacterial deoxyribonucleic acid hybridization.

Polynucleotide sequence relatedness can be studied with the S1 nuclease method by a fast and accurate procedure using DEAE-cellulose filters (DE81 Whatman). After S1 treatment of DNA-DNA hybrid molecules formed in 0.42 M saline solution, free nucleotides (digestion products) but not DNA are eluted from DE81 filters in appropriate salt concentration such as 5% Na2HPO4.

[Compatibility groups of metabolic plasmids (author's transl)].

The compatibility groups of eleven plasmids determining metabolic characters used in taxonomy and isolated from naturally-occurring strains were examined. Seven of these plasmids determined lactose fermentation. Two were fi+: one of these belonged to group FI and the other to a novel group.

[Plasmid determined lactose positive character in (Enterobacter hafniae) and (Proteus morganii) (author's transl)].

The atypical lactose positive characters have been found to be plasmidmediated in 6 strains of Enterobacter hafniae and 2 strains of Proteus morganii. One of the P. morganii plasmid possesses the fi+ character, all the other plasmids belonging to the fi-group.