Sporulation and Enterotoxin (CPE) Synthesis Are Controlled by the Sporulation-Specific Sigma Factors SigE and SigK inClostridium perfringens

Abstract

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 F , E , G , and 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 K dependent, while P2 and P3 were proposed to be 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 E -associated RNA polymerase and 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 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.

The Clostridium Sporulation Programs: Diversity and Preservation of Endospore Differentiation

“…5) (63). In the same study, a sigE disruption mutant (strain KM2) was also generated (63). The authors of this study reported that sporulation was blocked at an earlier stage in the sigK disruption mutant than in the sigE disruption mutant.…”

“…This sigK disruption mutant was unable to sporulate efficiently, and transmission electron microscopy (TEM) images showed that only a very small number of cells developed any kind of asymmetric septa or accumulated granulose, thus suggesting that sporulation was blocked prior to stage II ( Fig. 5) (63). In the same study, a sigE disruption mutant (strain KM2) was also generated (63).…”

“…Therefore, it appears that the skin Cd element is necessary for the proper spatial and temporal activation of K in C. difficile. The first evidence showing that K in Clostridium organisms may play an earlier role than in the B. subtilis model came from a sigK disruption mutant (strain KM1) generated in C. perfringens (63). This sigK disruption mutant was unable to sporulate efficiently, and transmission electron microscopy (TEM) images showed that only a very small number of cells developed any kind of asymmetric septa or accumulated granulose, thus suggesting that sporulation was blocked prior to stage II ( Fig.…”

Esporas de Clostridium difficile y su relevancia en la persistencia y transmisión de la infección

“…Al respecto, se han encontrado tres reguladores involucrados en la producción de toxina por parte de C. difficile: Ccpa, mediando la represión dependiente de glucosa; CodY y Spo0A; estos dos últimos controlando eventos previos y posteriores a la fase exponencial de crecimiento 104 . En C. perfringens, σ K es producido en células en la fase pre-divisional y se encuentra involucrado en la producción de enterotoxina 105 . En cuanto a C. difficile, un estudio mostró que en relación a los roles de los distintos factores sigma involucrados en esporulación, C. difficile parece ser cercano al organismo modelo, B. subtilis, más que a otras especies del género Clostridium 106 .…”

The Ger Receptor Family from Sporulating Bacteria

“…Firstly, chromosomal enterotoxin (from SM101 strain) and plasmid enterotoxin (from F5603 strain) are 100% identical at the amino acid level. Secondly, Although cpe is expressed during sporulation, the enterotoxin remains in the mother cell and not in the spore (Harry et al, 2009). Thus, the function of the enterotoxin in modulating germination response of C. perfringens spores is not clear.…”