ABSTRACT
Spo0A activates transcription in Bacillus subtilis from promoters that are used by two types of RNA polymerase, RNA polymerase containing the primary sigma factor, ςA, and RNA polymerase containing a secondary sigma factor, known as ςH. The region of ςA near positions 356 to 359 is required for Spo0A-dependent promoter activation, possibly because Spo0A interacts with this region of ςA at these promoters. To determine if the amino acids in the corresponding region of ςH are also important in Spo0A-dependent promoter activation, we examined the effects of single alanine substitutions at 10 positions in ςH (201 to 210). Two alanine substitutions in ςH, at glutamine 201 (Q201A) and at arginine 205 (R205A), significantly decreased activity from the Spo0A-dependent, ςH-dependent promoterspoIIA but did not affect expression from the ςH-dependent, Spo0A-independent promoterscitGp2 and spoVG. Therefore, promoter activation by Spo0A requires homologous regions in ςA and ςH. A mutant form of Spo0A, S231F, that suppresses the sporulation defect caused by several amino acid substitutions in ςA did not suppress the sporulation defects caused by the Q201A and R205A substitutions in ςH. This result and others indicate that different surfaces of Spo0A probably interact with ςA and ςH RNA polymerases.
Differential transcriptional profile of Corynebacterium pseudotuberculosis in response to abiotic stresses
