Role of an orphan ribonuclease in Bacillus subtilis spore development – BSpoRNase

When facing severe nutritional stress, the Gram-positive model bacterium Bacillus subtilis forms highly resistant spores, one the best-studied developmental programs in bacteria. We have identified a new exoribonuclease called KapD that is expressed specifically in the mother cell during sporulation and is required for the adhesion of the different layers that make up the protective spore coat and crust. Remarkably, KapD dynamically assembles over the spore surface with kinetics very similar to that of outer spore coat proteins. A yeast two-hybrid screen suggests that KapD interacts with a major spore crust protein, a key endoribonuclease and a helicase. In growing bacteria, endo- and exoribonucleases and RNA helicases form RNA-degrading machines called degradosomes. Our findings open the possibility that KapD is part of a sporulation-specific degradosome-like complex with an additional role in spore coat assembly. The goal of this project is to characterize these functions of KapD.