Bordetella pertussis toxin A (IPR003898)

Short name: Borpert_toxA

Overlapping homologous superfamilies


Family relationships



A large group of bacterial exotoxins are referred to as "A/B toxins", essentially because they are formed from two subunits [PMID: 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 [PMID: 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 [PMID: 3704651, PMID: 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 [PMID: 3704651, PMID: 2873570]. Uninhibited, this enzyme produces elevated levels of cAMP, leading to increased cell exudate and inflammation in the lungs [PMID: 2737291].

The crystal structure of pertussis toxin has been determined to 2.9A resolution [PMID: 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.

GO terms

Biological Process

GO:0009405 pathogenesis

Molecular Function

GO:0003950 NAD+ ADP-ribosyltransferase activity

Cellular Component

GO:0005576 extracellular region

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.