Studies on Ribonucleic Acid Ligase

• Published in: The Journal of biological chemistry Vol. 249; no. 23; pp. 7447 - 7456
• Main Authors: Cranston, Joseph W., Silber, Robert, Malathi, V.G., Hurwitz, Jerard
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 10-12-1974
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)81259-0

RNA ligase, isolated from bacteriophage T4-infected Escherichia coli , catalyzes the conversion of synthetic [5'- 32 P]polyribonucleotides to a form resistant to alkaline phosphatase. The reaction requires ATP and leads to the formation of
AMP and PP i . The purification procedure for T4-induced RNA ligase has been modified to yield stable enzyme preparations. The influence
of secondary structure on the RNA ligase reaction has been investigated with these fractions. The conversion of synthetic
polynucleotides to complex secondary structures was either without effect or inhibitory in the RNA ligase system. Purified
RNA ligase was shown to catalyze an exchange reaction between ATP and PP i , but not between ATP and AMP. The ATP-PP i exchange reaction occurred in the absence of a polyribonucleotide substrate. The formation of an RNA ligase-adenylate complex
was demonstrated by gel filtration, polyacrylamide gel electrophoresis, and ultracentrifugation in a glycerol gradient. The
complex was dissociated by 5'-P-poly(A) to yield AMP while ATP was generated in the presence of PP i . These findings suggest that an enzyme-AMP intermediate occurs during the course of the RNA ligase reaction. Evidence is
presented for the occurrence of an RNA ligase activity in eukaryotic cells.