MYXOCOCCUS-XANTHUS ENCODES AN ATP-DEPENDENT PROTEASE WHICH IS REQUIRED FOR DEVELOPMENTAL GENE-TRANSCRIPTION AND INTERCELLULAR SIGNALING

The bsgA gene of Myxococcus xanthus plays an essential role in the reg ulation of early gene expression during fruiting body formation and sp orulation. bsgA mutants behave as though unable to initiate a required cell-cell interaction and consequently fail to transcribe normal leve ls of many developmentally induced genes. We determined the nucleotide sequence of bsgA, which predicts a single gene encoding a 90.4-kDa pr otein. The deduced BsgA protein shares 45 and 48% amino acid identity with the lon genes of Escherichia coli and Bacillus brevis, respective ly. The cloned bsgA gene was expressed in E. coli, and the BsgA protei n was partially purified and found, like its E. coli homolog, to be an ATP-dependent protease. Thus, the basis for the phenotype of bsgA mut ants is likely to be a defect in intracellular proteolysis.