Cloning and characterization of the RNase P RNA genes from tow porcine mycoplasmas

Abstract

We report the cloning of the RNase P RNA genes from the primary aetiological agent of porcine pneumonia, Mycoplasma hyopneumoniae, and the closely related commensal, Mycoplasma flocculare. The monocistronic genes each have promoters with AT‐rich ‐35 regions and Rho‐independent‐like transcription terminators which are retained in the RNase P RNA. Both of these RNase P RNA variants are shown to be catalytically active in vitro in spite of a low overall GC content (30%). Our results suggest a new example of a stable mini‐helix in the conserved core of the mycoplasmal RNase P RNAs. Deletion of the corresponding structural element in Escherichia coli RNase P RNA (M1 RNA) generated an RNase P RNA with an impaired substrate interaction. Displacement of this structural element with the mycoplasmal mini‐helix resulted in an enzyme with a phenotype similar to that of wild‐type M1 RNA. in addition, this structural element is important for lead ion‐induced cleavage at specific sites in M1 RNA.