Conformational Dynamics of Self-thiophosphorylating RNA

摘要

The Kin.46 kinase ribozyme was previously selected from a random-sequence RNA library that was loosely based on the sequence of a known ATP aptamer,based on its ability to catalyze transfer of the thiophosphate from ATPgS to its own 5'hydroxyl end.The reaction requires an oligonucleotide effector that is complementary to the 3'end of the ribozyme and that served as reverse transcription primer during the amplification steps of the original selection for activity (Fig.1).Omitting the oligonucleotide reduces the observed catalytic rate constant (k_(obs)) by 10~3 to 10~6-fold,indicating that the oligo acts as an allosteric effector that is necessary for full catalytic activity.The activator helix is separated from the substrate-binding internal guide sequence by a 5nt "linker"that appears to form long-range base-paring interaction with nucleotides within the catalytic core (S.Rhee,unpublished results).