Pertussis toxin B-oligomer subunit S2 and S3 (PTx-S2/S3)

Pertussis toxin (PTx) is a hexameric AB5-type exotoxin and a primary virulence factor of Bordetella pertussis, the causative agent of whooping cough (UniProt P04978, P04979). The B-oligomer, which includes the S2 and S3 subunits, is responsible for the toxin's attachment to host cell membranes and the subsequent translocation of the enzymatic A-subunit (S1) into the cytoplasm (PMID: 1560113). The S2 and S3 subunits function as lectins; S2 specifically binds to haptoglobin-like glycoproteins, while S3 targets receptors on the surface of leukocytes, such as the Mac-1 (CD11b/CD18) integrin (PMID: 10417341). This binding is essential for the toxin's ability to disrupt G protein-coupled receptor signaling by allowing the S1 subunit to ADP-ribosylate inhibitory G proteins. In addition to their role in toxin entry, the S2 and S3 subunits can independently induce biological effects, such as T-cell mitogenesis and the stimulation of glucose metabolism. These subunits are critical antigens in acellular pertussis vaccines, where they are used to induce neutralizing antibodies that prevent the toxin from binding to host cells (CDC, 2023). Therapeutic strategies also include the development of monoclonal antibodies, such as Hu1B7, that specifically target the B-oligomer to mitigate the severity of pertussis symptoms.

Other names

Pertussis toxin subunit 2Pertussis toxin subunit 3PtxB subunitsBordetella pertussis toxin S2 and S3Islet-activating protein subunits S2 and S3PT S2PT S3

Neutralization of toxin binding to host cell receptors and induction of protective humoral immunity.