Multiple nucleotide cofactor use by yeast ligase in tRNA splicing: Evidence for independent ATP- and GTP-binding sites

Heather G. Belford, Shawn Westaway, John Abelson, Chris L. Greer

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

We have examined multiple cofactor usage by yeast tRNA ligase in splicing in vitro. The ligase mechanism of action requires expenditure of two molar equivalents of nucleotide cofactor per mole of tRNA product. Recent evidence (Westaway, S. K., Belford, H. G., Apostol, B. L., Abelson, J., and Greer, C. L. (1993) J. Biol. Chem. 268, 2435-2443) demonstrated that the ligase-associated kinase activity is more efficient with GTP as cofactor than with ATP. Employing a ligase fusion construct with dihydrofolate reductase (Apostol, B. L., Westaway, S. K., Abelson, J., and Greer, C. L. (1991) J. Biol. Chem. 266, 7445-7455) for purposes of enzyme purification, we performed joining assays demonstrating that ATP and GTP are the most effective combination of cof actors. ATP was essential to the joining reaction, while UTP, CTP, or ATP replaced GTP inefficiently. Specific and functionally independent binding sites were confirmed for ATP and GTP by direct binding measurement. A third site was implicated in UTP- and CTP-ligase interactions. Comparison of binding constants with Kapp values determined for nucleotide-dependent joining suggested both that nucleotide triphosphate binding may be limiting in tRNA joining and that tRNA ligation occurs most efficiently using GTP for the kinase reaction and ATP as the adenylylate synthetase cofactor.

Original languageEnglish (US)
Pages (from-to)2444-2450
Number of pages7
JournalJournal of Biological Chemistry
Volume268
Issue number4
StatePublished - Feb 5 1993
Externally publishedYes

Fingerprint

Ligases
Transfer RNA
Guanosine Triphosphate
Yeast
Nucleotides
Adenosine Triphosphate
Binding Sites
Joining
Cytidine Triphosphate
Uridine Triphosphate
Phosphotransferases
Tetrahydrofolate Dehydrogenase
Health Expenditures
Purification
Ligation
yeast tRNA ligase
Assays
Fusion reactions
Enzymes

ASJC Scopus subject areas

  • Biochemistry

Cite this

Multiple nucleotide cofactor use by yeast ligase in tRNA splicing : Evidence for independent ATP- and GTP-binding sites. / Belford, Heather G.; Westaway, Shawn; Abelson, John; Greer, Chris L.

In: Journal of Biological Chemistry, Vol. 268, No. 4, 05.02.1993, p. 2444-2450.

Research output: Contribution to journalArticle

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