Covalent catalysis in nucleotidyl transfer: A KTDG motif essential for enzyme-GMP complex formation by mRNA capping enzyme is conserved at the active sites of RNA and DNA ligases Journal Article
| Authors: | Cong, P.; Shuman, S. |
| Article Title: | Covalent catalysis in nucleotidyl transfer: A KTDG motif essential for enzyme-GMP complex formation by mRNA capping enzyme is conserved at the active sites of RNA and DNA ligases |
| Abstract: | Vaccinia virus RNA capping enzyme, a heterodimer of 95- and 31-kDa subunits, catalyzes transfer of GMP from GTP to the 5′-diphosphate terminus of RNA via a covalent enzyme-guanylate intermediate. The GMP residue is attached to the 95-kDa subunit through a phosphoamide bond to the ε-amino group of a lysine residue. The amino acid sequence of the large subunit includes a lysine-containing motif, Tyr-X-X-X-Lys260-Thr-Asp-Gly, that is conserved in the RNA guanylyltranferases encoded by Shope fibroma virus and Saccharomyces cerevisiae. The KXDG motif is also encountered at the sites of covalent adenylylation of bacteriophage T4 RNA ligase and mammalian DNA ligase I (Thogerson, H. C., Morris, H. R., Rand, K. N., and Gait, M. J. (1985) Eur. J. Biochem. 147, 325-329; Tomkinson, A. E., Totty, N. F., Ginsburg, M., and Lindahl, T. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 400-404). We find that conservative amino acid substitutions at three out of four positions within the KTDG sequence of vaccinia capping enzyme either prevent or strongly inhibit enzyme-guanylate formation. The conserved motif is therefore an essential component of the guanylyltransferase domain. Lys260 is implicated as the active site. Comparison of the sequences of capping enzymes and polynucleotide ligases from diverse sources suggests that KX(D/N)G may be a signature element for covalent catalysis in nucleotidyl transfer. |
| Keywords: | mutation; mammalia; amino acid substitution; enzyme activity; tyrosine; cloning, molecular; methyltransferases; amino acid sequence; conserved sequence; molecular sequence data; messenger rna; virus rna; saccharomyces cerevisiae; vaccinia virus; protein induction; threonine; binding sites; catalysis; multienzyme complexes; polydeoxyribonucleotide synthase; enzyme substrate complex; enzyme subunit; guanosine triphosphate; phosphoric monoester hydrolases; aspartic acid; lysine; rna ligase (atp); glycine; enzyme mechanism; electrophoresis, polyacrylamide gel; dna ligases; enzyme active site; nucleotide; vaccinia; nucleotides; rna capping; nucleotidyltransferases; nucleotide transport; rna ligase; guanosine phosphate; 5'-guanylic acid; priority journal; article; rabbit fibroma virus |
| Journal Title: | Journal of Biological Chemistry |
| Volume: | 268 |
| Issue: | 10 |
| ISSN: | 0021-9258 |
| Publisher: | American Society for Biochemistry and Molecular Biology |
| Date Published: | 1993-04-05 |
| Start Page: | 7256 |
| End Page: | 7260 |
| Language: | English |
| PUBMED: | 8385101 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Article -- Export Date: 1 March 2019 -- Source: Scopus |
