A NOVEL SPORULATION-CONTROL GENE (SPO0M) OF BACILLUS-SUBTILIS WITH A SIGMA(H)-REGULATED PROMOTER

A. novel sporulation-control gene (spo0M) of Bacillus subtilis was clo ned, sequenced and analyzed. The spo0M gene is located at the end of l arge tRNA gene clusters including rrnD and codes for a 257-amino-acid protein with a calculated size of 29.6 kDa. The protein Spo0M has a st rong negative charge (calculated pI=4.3) and shows no significant sequ ence homology to any known proteins. Gene disruption experiments revea led that spo0M is not essential for cell viability, but its disruption results in considerable impairments (decreasing by 20- to 100-fold) i n sporulation. The morphological stage blocked in sporulation was stag e 0 as observed by electron microscopy, and expression analysis using spo0Aps-bgaB fusion revealed an impaired gene expression of spo0A in t he spo0M mutant. In contrast, spo0M disruption had no effect on antibi otic productivity. Propagation of the spo0M gene in wild-type cells us ing a high-copy-number plasmid also impaired sporulation, indicating t hat overproduction of Spa0M exerts certain negative effects on sporula tion. spoaM gene expression is controlled by sigma(H), as demonstrated : (1) by monitoring expression of a bgaB transcriptional fusion integr ated into the amyE locus on the chromosome of the wild-type or spo0H m utant cells, and (2) by in-vitro transcription of spoaM gene with E si gma(H). (C) 1998 Elsevier Science B.V. All rights reserved.