Abstract
A RNA molecule has been synthesized that is identical in sequence to Escherichia coli tRNAfMet except that it lacks the base modifications present in the E. coli tRNA. This was achieved by enzymatic joining of chemically synthesized oligonucleotides with chain lengths of 3-10 which were synthesized by the phosphodiester or phosphotriester method. First, quarter molecules of tRNA were constructed by joining of chemically synthesized fragments with RNA ligase. The 5'-quarter molecule (bases 1-20) served as an acceptor in joining reactions with the 3',5'-bisphosphorylated donor molecule (bases 21-34). The 5'-half molecule thus obtained was treated with phosphatase and joined to the 3'-half molecule which was prepared by ligation of the other quarter molecules (bases 35-60, acceptor; bases 61-77, donor) followed by 5'-phosphorylation with polynucleotide kinase. The synthetic tRNA was characterized by oligonucleotide pattern and was partially active in aminoacylation with E. coli methionyl-tRNA synthetase.