RNASE-P RNA STRUCTURE AND CLEAVAGE REFLECT THE PRIMARY STRUCTURE OF TRANSFER-RNA GENES

The function of RNase P RNA depends on its folding in space. A majorit y of RNase P RNAs from various bacteria show a similar secondary struc ture to that of Escherichia coli (M1 RNA). However, there are exceptio ns as exemplified by the RNase P RNA derived from the low GC-content G ram-positive bacteria Bacillus subtilis and Mycoplasma hyopneumoniae ( Hyo P RNA). Previous studies using M1 RNA and Hyo P RNA suggest differ ences both with respect to the kinetics of cleavage as well as to clea vage site recognition. Here we have studied cleavage by these two stru cturally different RNase P RNAs as a function of changes in the 5' lea der anal the 3'-terminal CCA motif in the substrate. Our data suggest that the nucleotide at the -2 position in the 5' leader plays a role b oth for cleavage site recognition and for the rate of cleavage. Howeve r, depending on the identity of the -2 residue differences in the clea vage pattern comparing these two types of RNase P RNAs were observed. The results also suggest that the identity of the -1/+73 base-pair in the substrate influences the cleavage site recognition process. These findings will be related to differences in structure comparing these t ypes of RNase P RNAs and the ''RCCA-RNase P RNA'' interaction. In addi tion, our findings will be discussed with respect to the primary struc ture of the tRNA genes in different bacteria.;(C) 1998 Academic Press.