The GerW protein is essential for L-alanine-stimulated germination of Bacillus subtilis spores.

GerW (formerly called YtfJ) is a protein found in dormant spores of Bacillus subtilis. We have studied spore proteins in B. subtilis before, and here we report the characterization of GerW protein. Northern blot analysis revealed that gerW mRNA was transcribed by SigF-containing RNA polymerase beginning 1 h after the initiation of sporulation. Fluorescence was detected in forespores and dormant spores of B. subtilis recombinant strains expressing GerW-GFP. During germination in the presence of L-alanine or a mixture of L-asparagine, D-glucose, D-fructose and potassium ions (AGFK), normal spores of B. subtilis became darkened, stained positive with Hoechst 33342 and carboxyfluorescein diacetate succinimidyl ester (CFDA-SE), and released dipicolinic acid (DPA). In the case of gerW-deficient spores, AGFK triggered germination in a manner similar to that seen in the wild-type spores, whereas spores stimulated by L-alanine remained refractive under the phase contrast microscope, failed to stain positive with Hoechst 33342 or CFDA-SE, and released almost no DPA. These results indicate that GerW is essential for the L-alanine-induced breakdown of spore dormancy followed by core rehydration and the resumption of enzymatic activity, and suggest that GerW is involved in the early stages of germination in the presence of l-alanine.

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