Molecular and structural discrimination of proline racemase and hydroxyproline-2-epimerase from nosocomial and bacterial pathogens.

The first eukaryotic proline racemase (PRAC), isolated from the human Trypanosoma cruzi pathogen, is a validated therapeutic target against Chagas' disease. This essential enzyme is implicated in parasite life cycle and infectivity and its ability to trigger host B-cell nonspecific hypergammaglobulinemia contributes to parasite evasion and persistence. Using previously identified PRAC signatures and data mining we present the identification and characterization of a novel PRAC and five hydroxyproline epimerases (HyPRE) from pathogenic bacteria.

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.

Identification of RpoS (sigma(S))-regulated genes in Salmonella enterica serovar typhimurium.

The rpoS gene encodes the alternative sigma factor sigma(S) (RpoS) and is required for survival of bacteria under starvation and stress conditions. It is also essential for Salmonella virulence in mice. Most work on the RpoS regulon has been in the closely related enterobacterial species Escherichia coli.

The RcsB-RcsC regulatory system of Salmonella typhi differentially modulates the expression of invasion proteins, flagellin and Vi antigen in response to osmolarity.

Entry into intestinal epithelial cells is an essential feature in the pathogenicity of Salmonella typhi, which causes typhoid fever in humans. This process requires intact motility and secretion of the invasion-promoting Sip proteins, which are targets of the type III secretion machinery encoded by the inv, spa and prg loci. During our investigations into the entry of S.

Molecular characterization of the Salmonella typhi StpA protein that is related to both Yersinia YopE cytotoxin and YopH tyrosine phosphatase.

Analysis of the nucleotide sequence of a 4-kb DNA fragment located between the sip and iag loci on Salmonella typhi chromosome revealed three open reading frames, termed sipF, ctpA and stpA. The 82-amino-acid (aa) sipF product showed extensive similarity to the lacP protein from S. typhimurium.

Functional conservation of the Salmonella and Shigella effectors of entry into epithelial cells.

A Salmonella typhi chromosomal locus composed of five adjacent genes, designated sipEBCDA, was identified by transposon mutagenesis as being essential for cell invasion. Products of the sip genes exhibit extensive sequence similarities to the effectors of Shigella entry into epithelial cells encoded by the virulence plasmid-borne ipa operon. Expression of sipE and sipB in a Shigella non-invasive ipaB mutant restored the ability to invade epithelial cells.

Rapid detection of Salmonella subspecies I by PCR combined with non-radioactive hybridisation using covalently immobilised oligonucleotide on a microplate.

A polymerase chain reaction (PCR)-based test was developed for the detection of Salmonella. One pair of oligonucleotide primers was designed to amplify a 93-bp fragment of a gene required for the invasion of HeLa cells by Salmonella ser Typhi strain Ty2. The amplified product was analysed by non-radioactive sandwich hybridisation in microtiter plates using two oligonucleotides.

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.

[Characterization of a 7th subspecies of Salmonella: S. choleraesuis subsp. indica subsp. nov].

A new Salmonella subspecies designated as S. choleraesuis subsp. indica (shortly, subspecies VI) was delineated on the basis of biochemical characters and genomic relatedness.