Function of 2'-hydroxyl group of ribose in interaction between yeast alanyl tRNA and its aminoacyl tRNA synthetase

摘要

At the beginning of the 1980s Cech and Altaian independently discovered that RNA has enzyme activity and in 1982 Cech proposed the term "ribozyme " for an RNA with enzyme-like properties. From then on more people believe that the self-reproducing system could have consisted of RNA alone. In the long period of evolution, DNA replaced RNA as the major genetic information-carrier and protein replaced RNA as the major biocatalyst—enzyme. But RNA which plays a crucialrole in the protein biosynthesis is still an important biomacromolecule. Why could not the biological function of the modem RNA molecule be replaced by other macro-molecules, such as DNA or protein? Cedergren found that the catalytic function of hammerhead ribozyme depends not only on its secondary structure and some conserved nucleotides, but also on 2'-hydroxyl groups of ribose in some nucleotides. That means 2'-hydroxyl groups in the hammerhead ribozyme take part in the chemical reaction. It appearsto us that some 2'-hydroxyl groups in tRNA may also take part in the protein biosynthesis. First we demonstrated that 2'-hydroxyl groups of ribose in the anticodon of yeast alanyl tRNA are important for its incorporation activity (another paper acceptedby Chinese Science Bulletin). Then we want to check whether 2'-hydroxyl groups in other part of this tRNA is also essential for the interaction between tRNA and its aminoacyl tRNA synthetase. SchimmeP s laboratory has demonstrated that microhelices consisting of accepting stem of E. coli alanyl tRNA can be recognized by its synthetase. Four microhelices containing the accepting stem of yeast alanyl tRNA with different numbers of ribose and deoxyribose were therefore synthesized to study the function of2'-hydroxyl groups in the interaction between this tRNA and its aminoacyl tRNA synthetase.