TpsB
TpsB is an outer membrane protein that functions as the secretion gateway in the two-partner secretion (TPS) system found in many Gram-negative bacteria. In TPS, a separate protein TpsA is synthesized with an N-terminal signal peptide for Sec-dependent export to the periplasm; after crossing the periplasm, TpsA engages with its cognate TpsB at the outer membrane and is translocated out of the cell. TpsB thus determines substrate specificity and forms the conduit through which the mature TpsA passenger is exported.
Structural features: TpsB proteins typically comprise one or more periplasmic POTRA (polypeptide-transport-associated) domains that mediate interactions
Examples and biology: The best-characterized TPS pair is FhaC/FhaB in Bordetella pertussis, where FhaB encodes filamentous
Genetic and practical notes: TpsA and TpsB genes are often co-located in operons encoding the TPS pair,