A putative ATP-binding cassette transporter YbdA involved in sporulation of Bacillus subtilis

Insertional mutagenesis with mini-Tn10 was performed to identify new genes involved in sporulation of Bacillus subtilis. Here, we report on the characterization of the ybdA locus, which encodes a putative ATP-binding cassette transporter. The ybdA gene is the 6th cistron of the putative ybcOPQST-ybdABDE operon. A deletion mutation in ybdA and an insertional mutation in ybdB exhibited highly oligosporogenous phenotypes and led to a decrease in the transcription controlled by Spo0A, which is a key response regulator required for the initiation of sporulation. We further observed that the transcription of this operon was strongly induced after the end of the exponential growth phase in the wild-type strain, but not in a spo0A null mutant. Our data suggest that the YbdA and YbdB proteins are able to affect incorporation of nutrient signals during initiation of sporulation and may act as components of positive feedback systems of Spo0A activation.