Pertussis toxin subunit 1 (PT-S1)

Pertussis toxin subunit 1 (S1) is the enzymatically active component of the hexameric AB5-type exotoxin produced by Bordetella pertussis, the causative agent of whooping cough (UniProt: P04977). The S1 subunit functions as an ADP-ribosyltransferase that specifically targets the alpha subunits of the Gi/o family of heterotrimeric G proteins (PubMed: 2510062). By transferring an ADP-ribose moiety from NAD+ to a cysteine residue near the C-terminus of the G-protein, S1 prevents the G-protein from interacting with its cognate G protein-coupled receptors (GPCRs), thereby disrupting inhibitory signaling pathways and increasing intracellular cAMP levels (PubMed: 1640746). In the context of disease, this disruption leads to impaired immune cell recruitment, lymphocytosis, and the characteristic paroxysmal cough associated with pertussis infection (StatPearls: NBK470437). Therapeutically, the S1 subunit is a primary component of acellular pertussis vaccines, where it is chemically or genetically inactivated to form a toxoid that elicits protective neutralizing antibodies (PubMed: 10457516). Additionally, it serves as a critical tool in pharmacological research for investigating GPCR-mediated signaling by uncoupling receptors from inhibitory G-proteins.

Other names

PtxAIslet-activating protein subunit S1Pertussis toxin A subunitADP-ribosyltransferase pertussis toxin subunit 1

Vaccines utilize inactivated S1 (toxoid) to induce neutralizing antibodies that prevent toxin-mediated cellular damage; monoclonal antibodies bind to and neutralize the toxin's enzymatic or binding capacity.