title: Effect of iron on cytolysin A expression in Salmonella enterica serovar Typhi.
abstract: Previously, a novel protein ClyA (Cytolysin A) has been identified in Escherichia coli K-12, Salmonella enterica serovars Typhi and Paratyphi A and Shigella. Salmonella spp. synthesize substantial amounts of ClyA upon infection of the human host, although the mechanism by which ClyA is induced in vivo is unclear. Since environmental signals could control the expression of virulence determinants, ClyA expression in S. Typhi Ty2 was tested by Western blotting in the presence of normal pooled human serum (NPS). The level of ClyA expression increased in the presence of NPS in a concentration-dependent manner. RPMI 1640 medium similarly induced ClyA expression. ClyA expression was inversely proportional to the concentration of iron in RPMI medium. Therefore, we speculated that iron inhibited the expression of ClyA in S. Typhi Ty2, and free iron depletion may be one of the causes of S. Typhi-mediated induction of ClyA in vivo. Transcription from a clyA-lacZ fusion gene decreased as iron concentration increased, but not as significantly as the ClyA protein expression. It is concluded that the regulatory effect of iron on clyA expression is mainly at translational level.
authors.affiliation: Department of Microbiology, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Cui
authors.forename: Honghua
authors.initials: H
authors.lastname: Piao
authors.forename: Shen
authors.initials: S
authors.lastname: Jin
authors.forename: Hee Sam
authors.initials: HS
authors.lastname: Na
authors.forename: Yeongjin
authors.initials: Y
authors.lastname: Hong
authors.forename: Hyon E
authors.initials: HE
authors.lastname: Choy
authors.forename: Phil Youl
authors.initials: PY
authors.lastname: Ryu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015536:Down-Regulation; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D012480:Salmonella Infections / Q000382:microbiology*; D012485:Salmonella typhi / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006460:Hemolysin Proteins; C087744:ApxI toxin, Bacteria; D007501:Iron