The CcpA Protein Is Necessary for Efficient Sporulation and Enterotoxin Gene (cpe) Regulation in Clostridium perfringens
AUTOR(ES)
Varga, John
FONTE
American Society for Microbiology
RESUMO
Clostridium perfringens is the cause of several human diseases, including gas gangrene (clostridial myonecrosis), enteritis necroticans, antibiotic-associated diarrhea, and acute food poisoning. The symptoms of antibiotic-associated diarrhea and acute food poisoning are due to sporulation-dependent production of C. perfringens enterotoxin encoded by the cpe gene. Glucose is a catabolite repressor of sporulation by C. perfringens. In order to identify the mechanism of catabolite repression by glucose, a mutation was introduced into the ccpA gene of C. perfringens by conjugational transfer of a nonreplicating plasmid into C. perfringens, which led to inactivation of the ccpA gene by homologous recombination. CcpA is a transcriptional regulator known to mediate catabolite repression in a number of low-G+C-content gram-positive bacteria, of which C. perfringens is a member. The ccpA mutant strain sporulated at a 60-fold lower efficiency than the wild-type strain in the absence of glucose. In the presence of 5 mM glucose, sporulation was repressed about 2,000-fold in the wild-type strain and 800-fold in the ccpA mutant strain compared to sporulation levels for the same strains grown in the absence of glucose. Therefore, while CcpA is necessary for efficient sporulation in C. perfringens, glucose-mediated catabolite repression of sporulation is not due to the activity of CcpA. Transcription of the cpe gene was measured in the wild-type and ccpA mutant strains grown in sporulation medium by using a cpe-gusA fusion (gusA is an Escherichia coli gene encoding the enzyme β-glucuronidase). In the exponential growth phase, cpe transcription was two times higher in the ccpA mutant strain than in the wild-type strain. Transcription of cpe was highly induced during the entry into stationary phase in wild-type cells but was not induced in the ccpA mutant strain. Glucose repressed cpe transcription in both the wild-type and ccpA mutant strain. Therefore, CcpA appears to act as a repressor of cpe transcription in exponential growth but is required for efficient sporulation and cpe transcription upon entry into stationary phase. CcpA was also required for maximum synthesis of collagenase (kappa toxin) and acted as a repressor of polysaccharide capsule synthesis in the presence of glucose, but it did not regulate synthesis of the phospholipase PLC (alpha toxin).
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=490932Documentos Relacionados
- Identification and Characterization of Sporulation-Dependent Promoters Upstream of the Enterotoxin Gene (cpe) of Clostridium perfringens
- Development of a Duplex PCR Genotyping Assay for Distinguishing Clostridium perfringens Type A Isolates Carrying Chromosomal Enterotoxin (cpe) Genes from Those Carrying Plasmid-Borne Enterotoxin (cpe) Genes
- Multiplex PCR Genotyping Assay That Distinguishes between Isolates of Clostridium perfringens Type A Carrying a Chromosomal Enterotoxin Gene (cpe) Locus, a Plasmid cpe Locus with an IS1470-Like Sequence, or a Plasmid cpe Locus with an IS1151 Sequence
- The Functional ccpA Gene Is Required for Carbon Catabolite Repression in Lactobacillus plantarum
- Clostridium perfringens type A: in vitro system for sporulation and enterotoxin synthesis.