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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #127568
Title: CYTOPATHIC EFFECTS OBSERVED UPON EXPRESSION OF A REPRESSED COLLAGENASE GENE PRESENT IN SALMONELLA AND RELATED PATHOGENS: MIMICRY OF A CYTOTOXIN FROM MULTIPLE ANTIBIOTIC-RESISTANT SALMONELLA ENTERICA SEROTYPE TYPHIMURIUM PHAG

Author
item WU, MAX
item CARLSON, STEVEN
item MEYERHOLZ, DAVID - IOWA STATE UNIVERSITY

Submitted to: Microbial Pathogenesis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2002
Publication Date: 12/20/2002
Citation: WU, M.T., CARLSON, S.A., MEYERHOLZ, D. CYTOPATHIC EFFECTS OBSERVED UPON EXPRESSION OF A REPRESSED COLLAGENASE GENE PRESENT IN SALMONELLA AND RELATED PATHOGENS: MIMICRY OF A CYTOTOXIN FROM MULTIPLE ANTIBIOTIC-RESISTANT SALMONELLA ENTERICA SEROTYPE TYPHIMURIUM PHAGETYPE DT104. MICROBIAL PATHOGENESIS. 2002. V. 33. P. 279-287.

Interpretive Summary: Recently, our laboratory reported that certain strains of Salmonella enterica serovar Typhimurium phagetype DT104 secrete a putative cytotoxin (Ctx). In the follow-up studies concerning the genes that encode this cytotoxin, we cloned a DNA fragment from Salmonella and expressed its gene product (Clg) in Escherichia coli K-12 and Salmonella typhimurium. Liquid suspension of broken cells containing Clg protein from both bacterial hosts exerted similar deteriorating damage on murine ileum as those observed in our previous Ctx studies. Purified Clg protein was also able to elicit deteriorating effects in HEp-2 cells. Sequence and RT-PCR analyses of the clg gene indicated that a highly similar copy of the clg gene exists in different Gram- negative bacteria, but often is not expressed. Due to the transient nature of Ctx expression when the pathogen is outside of its mammalian host, we are unable to firmly establish Ctx and Clg as equivalents. However, we have defined at the molecular level a protein that is capable of inflicting damage on tissue culture cell and murine enterocytes. Furthermore, this study suggests that repressive mechanism may exist in which the expression of the clg gene is constantly inhibited. This information would be of interest to scientists, veterinarians, clinical microbiologists, veterinary diagnostic labs and veal calf producers.

Technical Abstract: Recently, we reported that certain strains of Salmonella enterica serovar Typhimurium phagetype DT104 secrete a putative cytotoxin (Ctx). In the process of searching for the potential gene(s) that encodes this toxin, we cloned a DNA fragment from Salmonella and expressed its corresponding gene product (Clg) in Escherichia coli K- 12 and Salmonella typhimurium. Cell lysates containing Clg from both hosts exerted similar cytotoxic damage on murine ileum as those observed in our previous Ctx studies. Purified Clg was also able to elicit cytotoxic effects in HEp-2 cells. Sequence and RT-PCR analyses of the clg gene indicated that homolog of clg exists in different Gram-negative bacteria, but often is not expressed. Due to the transient nature of Ctx expression in vitro, we are unable to firmly establish Ctx and Clg as equivalents. However, we have defined at the molecular level a protein that is capable of inflicting damage on tissue culture cell and murine enterocytes. Furthermore, this study suggests that negative regulation may exist in which clg is constitutively repressed.