Regulation of RraA, a protein inhibitor of RNase E-mediated RNA decay.

The recently discovered RraA protein acts as an inhibitor of the essential endoribonuclease RNase E, and we demonstrated that ectopic expression of RraA affects the abundance of more than 700 transcripts in Escherichia coli (K. Lee, X. Zhan, J. Gao, J. Qiu, Y. Feng, R. Meganathan, S. N. Cohen, and G. Georgiou, Cell 114:623-634, 2003). We show that rraA is expressed from its own promoter, P(rraA), located in the menA-rraA intergenic region. Primer extension and lacZ fusion analysis revealed that transcription from P(rraA) is elevated upon entry into stationary phase in a sigma(s)-dependent manner. In addition, the stability of the rraA transcript is dependent on RNase E activity, suggesting the involvement of a feedback circuit in the regulation of the RraA level in E. coli.