Bacillus subtilis sequence-independent DNA-binding and DNA-bending protein Hbsu negatively controls its own synthesis

Transcription of the hbs gene under vegetative growth condition is subject to repression when cells enter in late exponential phase. We have determined the sites at which transcription of the hbs gene initiates in vitro. On a supercoiled template, transcription of the hbs gene is initiated by sigma(A)RNAP at two overlapping hbs promoters (P1 and P3). We have demonstrated that highly purified Hbsu protein acts as a repressor of its own synthesis. The binding of the sequence-independent DNA-binding and DNA-bending Hbsu protein does not seem to exclude sigma(A)RNAP from the promoters. In this report we show that Hbsu, in vitro, does not repress transcription by a mere steric hindrance on sigma(A)RNAP binding. (C) 1999 Elsevier Science B.V. All rights reserved.