Document Detail

Evaluating the involvement of alternative sigma factors SigF and SigG in Clostridium perfringens sporulation and enterotoxin synthesis.
MedLine Citation:
PMID:  20643850     Owner:  NLM     Status:  MEDLINE    
Clostridium perfringens type A food poisoning is the second most commonly identified bacterial food-borne illness. Sporulation contributes to this disease in two ways: (i) most food-poisoning strains form exceptionally resistant spores to facilitate their survival of food-associated stresses, and (ii) the enterotoxin (CPE) responsible for the symptoms of this food poisoning is synthesized only during sporulation. In Bacillus subtilis, four alternative sigma factors mediate sporulation. The same four sigma factors are encoded by C. perfringens genomes, and two (SigE and SigK) have previously been shown to be necessary for sporulation and CPE production by SM101, a transformable derivative of a C. perfringens food-poisoning strain (K. H. Harry, R. Zhou, L. Kroos, and S. B. Melville, J. Bacteriol. 2009, 191:2728-2742). However, the importance of SigF and SigG for C. perfringens sporulation or CPE production had not yet been assessed. In the current study, after confirming that sporulating wild-type SM101 cultures produce SigF (from a tricistronic operon) and SigG, we prepared isogenic sigF- or sigG-null mutants. Whereas SM101 formed heat-resistant, phase-refractile spores, spore formation was blocked in the sigF- and sigG-null mutants. Complementation fully restored sporulation by both mutants. By use of these mutants and complementing strains, CPE production was shown to be SigF dependent but SigG independent. This finding apparently involved regulation of the production of SigE and SigK, which Harry et al. showed to be necessary for CPE synthesis, by SigF. By combining these findings with those previous results, it is now apparent that all four alternative sigma factors are necessary for C. perfringens sporulation, but only SigE, SigF, and SigK are needed for CPE synthesis.
Jihong Li; Bruce A McClane
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-07-19
Journal Detail:
Title:  Infection and immunity     Volume:  78     ISSN:  1098-5522     ISO Abbreviation:  Infect. Immun.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-09-22     Completed Date:  2010-11-12     Revised Date:  2014-09-22    
Medline Journal Info:
Nlm Unique ID:  0246127     Medline TA:  Infect Immun     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4286-93     Citation Subset:  IM    
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MeSH Terms
Bacterial Proteins / genetics,  physiology*
Blotting, Northern
Clostridium perfringens / classification,  genetics,  physiology*
Enterotoxins / biosynthesis*
Gene Deletion
Gene Expression Regulation, Bacterial / physiology*
Promoter Regions, Genetic / genetics
Sigma Factor / genetics,  physiology*
Spores, Bacterial
Transcription Factors / physiology
Grant Support
R37 AI019844/AI/NIAID NIH HHS; R37 AI019844-28/AI/NIAID NIH HHS; R37 AI19844-27/AI/NIAID NIH HHS
Reg. No./Substance:
0/Bacterial Proteins; 0/Enterotoxins; 0/FliA protein, Bacteria; 0/Sigma Factor; 0/Transcription Factors; 0/enterotoxin, Clostridium; 0/sigma K; 0/sporulation-specific sigma factors

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