A specific endoribonuclease, RNase P, affects gene expression of polycistronic operon mRNAs.

The rnpA mutation, A49, in Escherichia coli reduces the level of RNase P at 43 degrees C because of a temperature-sensitive mutation in C5 protein, the protein subunit of the enzyme. Microarray analysis reveals the expression of several noncoding intergenic regions that are increased at 43 degrees C compared with 30 degrees C. These regions are substrates for RNase P, and they are cleaved less efficiently than, for example, tRNA precursors. An analysis of the tna, secG, rbs, and his operons, all of which contain RNase P cleavage sites, indicates that RNase P affects gene expression for regions downstream of its cleavage sites.