Combination of cleavage site analysis and kinetic analysis of a series of shape variant of pre-tRNA substrate, we newly found two subsites which contribute to recognition of shape in substrate binding and catalysis by bacterial RNase P. Our data showed that the ribozyme traps the substrate by 5'- and 3'-end regions to form Michaelis complex, and after that the shape of the substrat is examied by other two subsites in the transition state. In the meeting, we will show the posibility that the S-domain can contribute to stabilize the transition state of the cleavage reaction of a pre-tRNA substrate. 10.1093/nass/nrp018