Ribonucleases J1 and J2: two novel endoribonucleases in B.subtilis with functional homology to E.coli RNase

Many prokaryotic organisms lack an equivalent of RNase E, which plays a key role in mRNA degradation in Escherichia coli. In this paper, we report the puri-fication and identification by mass spectrometry in Bacillus subtilis of two paralogous endoribonuc-leases, here named RNases J1 and J2, which share functional homologies with RNase E but no sequence similarity. Both enzymes are able to cleave the B.subtilis thrS leader at a site that can also be cleaved by E.coli RNase E. We have previously shown that cleavage at this site increases the stability of the downstream messenger. Moreover, RNases J1/J2 are sensitive to the 50 phosphorylation state of the substrate in a site-specific manner. Orthologues of RNases J1/J2, which belong to the metallo-b-lactamase family, are evolutionarily conserved in many prokaryotic organisms, representing a new family of endoribonucleases. RNases J1/J2 appear to be implicated in regulatory processing/maturation of specific mRNAs, such as the T-box family members thrS and thrZ, but may also contribute to global mRNA degradation