The nucleotide sequence and gene organization of the gerA spore germination operon of Bacillus subtilis 168

The nucleotide sequence of the second and third genes in the Bacillus subtilis spore germination locus, gerA, has been determined and the amino acid (aa) sequence was derived. Two open reading frames (ORFs), corresponding to genes II and III, encode 364-aa residue and 373-aa residue polypeptides, respectively. The gene II product, Mr 41,257, would contain long stretches of hydrophobic aa residues and may be a membrane protein; the gene III product, Mr 42,363, is relatively hydrophilic but possesses an apparent signal peptide for transfer across, and perhaps localisation on, a membrane. The ORFs for genes I and II overlap by eleven codons and the termination codon of gene II overlaps the initiation codon of gene III. Insertional inactivation experiments using integrational plasmids have indicated that the gerA locus is a single transcriptional unit. The expression of the gerA genes has been studied using a lacZ transcriptional fusion; they constitute a developmentally regulated operon.