title: Vectorial signalling mechanism required for cell-cell communication during sporulation in Bacillus subtilis.
abstract: Spore formation in Bacillus subtilis takes place in a sporangium consisting of two chambers, the forespore and the mother cell, which are linked by pathways of cell-cell communication. One pathway, which couples the proteolytic activation of the mother cell transcription factor σ(E)  to the action of a forespore synthesized signal molecule, SpoIIR, has remained enigmatic. Signalling by SpoIIR requires the protein to be exported to the intermembrane space between forespore and mother cell, where it will interact with and activate the integral membrane protease SpoIIGA. Here we show that SpoIIR signal activity as well as the cleavage of its N-terminal extension is strictly dependent on the prespore fatty acid biosynthetic machinery. We also report that a conserved threonine residue (T27) in SpoIIR is required for processing, suggesting that signalling of SpoIIR is dependent on fatty acid synthesis probably because of acylation of T27. In addition, SpoIIR localization in the forespore septal membrane depends on the presence of SpoIIGA. The orchestration of σ(E)  activation in the intercellular space by an acylated signal protein provides a new paradigm to ensure local transmission of a weak signal across the bilayer to control cell-cell communication during development.
authors: Instituto de Biología Molecular y Celular de Rosario and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, 2000 Rosario, Argentina.
authors: Veronica
authors: V
authors: Diez
authors: Gustavo E
authors: GE
authors: Schujman
authors: Frederico J
authors: FJ
authors: Gueiros-Filho
authors: Diego
authors: D
authors: de Mendoza
mesh_terms: D000215:Acylation; D001412:Bacillus subtilis / Q000254:growth & development* / Q000378:metabolism* / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism*; D002450:Cell Communication; D002462:Cell Membrane / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D010447:Peptide Hydrolases / Q000378:metabolism; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D012808:Sigma Factor / Q000378:metabolism*; D013171:Spores, Bacterial / Q000254:growth & development* / Q000378:metabolism* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D005227:Fatty Acids; D008565:Membrane Proteins; D012808:Sigma Factor; C092468:spoIIR protein, Bacillus subtilis; C063202:sporulation-specific sigma factors; D010447:Peptide Hydrolases; C071976:SpoIIGA protein, Bacillus subtilis