PROSITE documentation PDOC51494 [for PROSITE entry PS51494]

SpoIVB peptidase domain profile

The protein SpoIVB is a serine peptidase that plays a central role in a regulatory checkpoint (the sigma-K checkpoint) which coordinates gene expression during the later stages of spore formation in Bacillus subtilis. SpoIVB signal by transiting a membrane, undergoing self cleavage, and then by an unknown mechanism activating a zinc metalloprotease, SpoIVFB, which cleaves pro-sigma-K to its active form, sigma-K, in the outer mother cell chamber of the developing cell [E1]. Homologues of SpoIVB proteins have been identified in a number of spore-forming organisms. SpoIVB carries a single PDZ domain (see <PDOC50106>) and a 160-amino-acid residue catalytic serine peptidase domain at the carboxyl terminus of the protein. His, Asp and Ser residues form the catalytic triad of the SpoIVB serine peptidase domain [1,2]. The SpoIVB peptidase domain forms peptidase family S55 of clan PA(S) [2] [E1].

For SpoIVB to cleave another SpoIVB molecule in trans it must target a specific region at the COOH terminus of the SpoIVB peptidase domain. This region carries a Thr-His-Val motif identical to the classical PDZ recognition motif ([ST]-X-V) normally found at the extreme COOH terminus of PDZ-recognized proteins [2].

The profile we developed covers the entire SpoIVB peptidase domain.