Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.13.3 (histidine kinase)
 2,405 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A cytotoxin (CytK) has been isolated from a Bacillus cereus strain that caused a severe food poisoning outbreak killing three people. A protein of 34 kDa was highly cytotoxic, and the addition of other secreted proteins gave no synergistic effect. CytK was also necrotic and haemolytic. No known B. cereus enterotoxins were produced by this strain. A DNA sequence from 1.8 kb upstream to 0.2 kb downstream of the toxin gene was sequenced. The deduced amino acid sequence of the toxin showed similarity to Staphylococcus aureus leucocidins, gamma-haemolysin and alpha-haemolysin, Clostridium perfringens beta-toxin and B. cereus haemolysin II, all belonging to a family of beta-barrel channel-forming toxins. There was no sequence similarity between CytK and enterotoxins of B. cereus. The upstream sequence contained a partial sequence of a putative histidine kinase gene. A recognition site for PlcR, which regulates the transcription of enterotoxins HBL and Nhe of B. cereus, was found in the promoter region of the toxin. This new cytotoxin may be responsible for a disease that is similar to, although not as severe as, the necrotic enteritis caused by the beta-toxin of C. perfringens type C.
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PMID:A new cytotoxin from Bacillus cereus that may cause necrotic enteritis. 1106 52

The Gram-positive, anaerobic, spore-forming, rod-shaped Clostridium perfringens is widely distributed in nature, especially in soil and the gastrointestinal tract of humans and animals. C. perfringens causes clostridial myonecrosis (or gas gangrene), enteritis and enterotoxemia in humans and livestock by producing numerous extracellular toxins and enzymes. The toxin gene expression is regulated by a two-component regulatory system and regulatory RNA VirR/VirS-VR-RNA cascade. The VirR/VirS system was originally found in a type A strain, but a recent report showed that it is also important for the toxin gene regulation in other types of strains. Two types of cell-cell signaling, i.e., agr-system and AI-2 signaling, are also important for the regulation of toxin genes. Several regulatory systems independent from the VirR/VirS system, including virX, the orphan histidine kinase ReeS and orphan response regulator RevR, are also involved in the regulation of toxin genes. In addition, the expression of toxin genes is upregulated after contact with Caco-2 cells. C. perfringens has a complex regulatory network for toxin gene expression and thus the coordination of toxin gene expression is important for the process of infection.
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PMID:Regulation of toxin gene expression in Clostridium perfringens. 2530 32