title: SpoIVB-mediated cleavage of SpoIVFA could provide the intercellular signal to activate processing of Pro-sigmaK in Bacillus subtilis.
abstract: SpoIVB is the critical determinant for intercompartmental signalling of pro-sigmaK processing during sporulation in Bacillus subtilis. We show here that the SpoIVB serine peptidase can cleave the SpoIVFA protein, which is one component of the pro-sigmaK processing complex. SpoIVFA has been shown elsewhere (Rudner, D.Z., and Losick, R., 2002, Genes Dev 16: 1007-1018) to tether BofA and SpoIVFB in a membrane-embedded heteroligomeric complex in which BofA directly inhibits the activity of SpoIVFB. Cleavage of SpoIVFA would provide the necessary signal to dissolve this complex and release BofA-mediated inhibition on the zinc metalloprotease, SpoIVFB, that is responsible for cleaving pro-sigmaK to its mature form. We also show that the SpoIVB PDZ domain is required for self-recognition and trans cleavage of SpoIVB and is probably also used to target an internal motif within the C-terminal region of SpoIVFA exposed in the space between the inner and outer forespore membranes. This work reveals the mechanism of intercompartmental signalling and provides a unified model as to how sigmaK-directed gene expression in the mother cell is co-ordinated with events in the forespore chamber.
authors.affiliation: School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK.
authors.forename: Tran C
authors.initials: TC
authors.lastname: Dong
authors.forename: Simon M
authors.initials: SM
authors.lastname: Cutting
mesh_terms: D001412:Bacillus subtilis / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism*; D012808:Sigma Factor / Q000378:metabolism*; D013171:Spores, Bacterial / Q000254:growth & development / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D012097:Repressor Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C112176:pro-sigmaK protein, Bacillus subtilis; C074423:bofA protein, Bacillus subtilis; C071441:spoIVFA protein, Bacillus subtilis; D012697:Serine Endopeptidases