ART Database

A family of bacterial and eukaryotic ADP-ribosyltransferases that resemble pertussis toxin.

A large group of bacterial exotoxins are referred to as "A/B toxins", essentially because they are formed from two subunits [PUBMED:8225592]. The "A" subunit possesses enzyme activity, and is transferred to the host cell following a conformational change in the membrane-bound transport "B" subunit [PUBMED:8225592]. Bordetella pertussis is the causative agent of whooping cough, and is a Gram-negative aerobic coccus. Its major virulence factor is the pertussis toxin, an A/B exotoxin that mediates both colonisation and toxaemic stages of the the disease [PUBMED:3704651, PUBMED:2873570]. Recombinant, inactive forms of the 5 subunits that make up the toxin have proven to be good vaccines. The S1 ("A") subunit of pertussis toxin causes the characteristic sound of the "whoop" in whooping cough. It achieves this through ADP-ribosylation of host Gi alpha-units, an adenylate cyclase inhibitor [PUBMED:3704651, PUBMED:2873570]. Uninhibited, this enzyme produces elevated levels of cAMP, leading to increased cell exudate and inflammation in the lungs [PUBMED:2737291]. The crystal structure of pertussis toxin has been determined to 2.9A resolution [PUBMED:8075982]. The catalytic A-subunit (S1) shares structural similarity with other ADP-ribosylating bacterial toxins, although differences in the C-terminal portion explain its unique activation mechanism. Despite its heterogeneous subunit composition, the structure of the cell-binding B-oligomer (S2, S3, two copies of S4, and S5) resembles the symmetrical B-pentamers of the cholera and shiga toxin families, but it interacts differently with the A-subunit and there is virtually no sequence similarity between B-subunits of the different toxins.

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Source: Pfam 34.0, rp75 Number of sequences: 113 Average length of the domain: 104 aa HMM: Model length: 171 Clustering level: 80% Alignment: ClustalO Additional information: sequences longer than 50 amino acids