Temporal regulation of the Bacillus subtilis early sporulation gene spo0F

The initiation of sporulation in Bacillus subtilis depends on seven genes of the spo0 class. One of these, spo0F, codes for a protein of 14,000 daltons. We studied the regulation of spo0F by using spo0F-lacZ translational fusions and also measured Spo0F protein levels by immunoassays. spo0F-lacZ and Spo0F levels increased as the cells entered the stationary phase, and this effect was repressed by glucose and glutamine. Decoyinine, which lowers GTP levels and allows sporulation in the presence of normally repressing levels of glucose, induced spo0F-lacZ expression and raised Spo0F levels. The expression of spo0F-lacZ was dependent on spo0A, -0B, -0E, -0F, and -0H genes, a spo0H deletion causing the strongest effect. In most respects, the spo0F gene was regulated in a manner similar to that of spoVG. However, the presence of an abrB mutation did not relieve the dependence of spo0F gene expression on spo0A, as it does with spoVG (P. Zuber and R. Losick, J. Bacteriol. 169:2223-2230, 1987).     

Bacillus subtilis extracellular nuclease production associated with the spoOH sporulation locus

A number of nuclease-deficient mutants of Bacillus subtilis were isolated and found to be concurrently asporogenous. The nuclease-deficient phenotype appeared to be associated with the spoOH sporulation locus. Spontaneously occurring sporogenous revertants concomitantly recovered the ability to produce extracellular nuclease activity. The position of the ncl mutation was determined using transformation and PBS1 transduction and found to map in the same site as spoOH. The map order of ncl and markers in the vicinity was determined to be purA-cysA-ncl(spoOH)-strA.