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Journal of Bacteriology, April 2009, p. 2728-2742, Vol. 191, No. 8
0021-9193/09/$08.00+0     doi:10.1128/JB.01839-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Sporulation and Enterotoxin (CPE) Synthesis Are Controlled by the Sporulation-Specific Sigma Factors SigE and SigK in Clostridium perfringens{triangledown} ,{ddagger}

Kathryn H. Harry,1,{dagger} Ruanbao Zhou,2 Lee Kroos,2 and Stephen B. Melville1*

Department of Biological Sciences, 2119 Derring Hall, Virginia Tech University, Blacksburg, Virginia 24061,1 Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 488242

Received 31 December 2008/ Accepted 29 January 2009

Clostridium perfringens is the third most frequent cause of bacterial food poisoning annually in the United States. Ingested C. perfringens vegetative cells sporulate in the intestinal tract and produce an enterotoxin (CPE) that is responsible for the symptoms of acute food poisoning. Studies of Bacillus subtilis have shown that gene expression during sporulation is compartmentalized, with different genes expressed in the mother cell and the forespore. The cell-specific RNA polymerase sigma factors {sigma}F, {sigma}E, {sigma}G, and {sigma}K coordinate much of the developmental process. The C. perfringens cpe gene, encoding CPE, is transcribed from three promoters, where P1 was proposed to be {sigma}K dependent, while P2 and P3 were proposed to be {sigma}E dependent based on consensus promoter recognition sequences. In this study, mutations were introduced into the sigE and sigK genes of C. perfringens. With the sigE and sigK mutants, gusA fusion assays indicated that there was no expression of cpe in either mutant. Results from gusA fusion assays and immunoblotting experiments indicate that {sigma}E-associated RNA polymerase and {sigma}K-associated RNA polymerase coregulate each other's expression. Transcription and translation of the spoIIID gene in C. perfringens were not affected by mutations in sigE and sigK, which differs from B. subtilis, in which spoIIID transcription requires {sigma}E-associated RNA polymerase. The results presented here show that the regulation of developmental events in the mother cell compartment of C. perfringens is not the same as that in B. subtilis and Clostridium acetobutylicum.

* Corresponding author. Mailing address: Department of Biological Sciences, 2119 Derring Hall, Virginia Tech University, Blacksburg, VA 24061. Phone: (540) 231-1441. Fax: (540) 231-9307. E-mail: melville{at}vt.edu

{triangledown} Published ahead of print on 6 February 2009.

{ddagger} Supplemental material for this article may be found at http://jb.asm.org/.

{dagger} Present address: TechLab, 2001 Kraft Drive, Blacksburg, VA 24060-6358.

Journal of Bacteriology, April 2009, p. 2728-2742, Vol. 191, No. 8
0021-9193/09/$08.00+0     doi:10.1128/JB.01839-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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