Characterization of a Pore-Forming Cytotoxin Expressed by Salmonella enterica Serovars Typhi and Paratyphi A

AUTOR(ES)

Oscarsson, Jan

FONTE

American Society for Microbiology

RESUMO

Cytolysin A (ClyA) is a pore-forming cytotoxic protein encoded by the clyA gene that has been characterized so far only in Escherichia coli. Using DNA sequence analysis and PCR, we established that clyA is conserved in the human-specific typhoid Salmonella enterica serovars Typhi and Paratyphi A and that the entire clyA gene locus is absent in many other S. enterica serovars, including Typhimurium. The gene products, designated ClyASTy and ClyASPa, show ≥90% amino acid identity to E. coli cytolysin A, ClyAEC, and they are immunogenically related. The Salmonella proteins showed a pore-forming activity and are hence functional homologues to ClyAEC. The chromosomal clyASTy gene locus was expressed at detectable levels in the serovar Typhi strains S2369/96 and S1112/97. Furthermore, in the serovar Typhi vaccine strain Ty21a, expression of clyASTy reached phenotypic levels, as detected on blood agar plates. The hemolytic phenotype was abolished by the introduction of an in-frame deletion in the clyASTy chromosomal locus of Ty21a. Transcomplementation of the mutant with a cloned clyASTy gene restored the hemolytic phenotype. To our knowledge, Ty21a is the first reported phenotypically hemolytic Salmonella strain in which the genetic determinant has been identified.

Documentos Relacionados

• Pore-forming peptide of pathogenic Entamoeba histolytica.
• Luminal loop of the ryanodine receptor: A pore-forming segment?
• Rational combinatorial design of pore-forming β-sheet peptides
• Carbohydrate-reactive, pore-forming outer membrane proteins of Aeromonas hydrophila.
• Pore-forming toxins trigger shedding of receptors for interleukin 6 and lipopolysaccharide.