The
RNase E/G family of
endoribonucleases plays the central role in numerous post-transcriptional mechanisms in Escherichia coli and, presumably, in other bacteria, including human pathogens. To learn more about specific properties of
RNase E/G homologues from pathogenic Gram-positive bacteria, a
polypeptide comprising the catalytic domain of Mycobacterium tuberculosis
RNase E/G (MycRne) was purified and characterized in vitro. In the present study, we show that affinity-purified MycRne has a propensity to form dimers and tetramers in
solution and possesses an endoribonucleolytic activity, which is dependent on the 5'-phosphorylation status of
RNA. Our data also indicate that the cleavage specificities of the M.
tuberculosis RNase E/G homologue and its E. coli counterpart are only moderately overlapping, and reveal a number of sequence determinants within MycRne cleavage sites that differentially affect the efficiency of cleavage. Finally, we demonstrate that, similar to E. coli
RNase E, MycRne is able to cleave in an
intercistronic region of the putative 9S precursor of
5S rRNA, thus suggesting a common function for
RNase E/G homologues in rRNA processing.