Mutational analysis of the guanylyltransferase component of mammalian mRNA capping enzyme Journal Article
| Authors: | Sawaya, R.; Shuman, S. |
| Article Title: | Mutational analysis of the guanylyltransferase component of mammalian mRNA capping enzyme |
| Abstract: | RNA guanylyltransferase is an essential enzyme that catalyzes the second of three steps in the synthesis of the 5′-cap structure of eukaryotic mRNA. Here we conducted a mutational analysis of the guanylyltransferase domain of the mouse capping enzyme Mce1. We introduced 50 different mutations at 22 individual amino acids and assessed their effects on Mce1 function in vivo in yeast. We identified 16 amino acids as being essential for Mce1 activity (Arg299, Arg315, Asp343, Glu345, Tyr362, Asp363, Arg380, Asp438, Gly439, Lys458, Lys460, Asp468, Arg530, Asp532, Lys533, and Asn537) and clarified structure-activity relationships by testing the effects of conservative substitutions. The new mutational data for Mce1, together with prior mutational studies of Saccharomyces cerevisiae guanylyltransferase and the crystal structures of Chlorella virus and Candida albicans guanylyltransferases, provide a coherent picture of the functional groups that comprise and stabilize the active site. Our results extend and consolidate the hypothesis of a shared structural basis for catalysis by RNA capping enzymes, DNA ligases, and RNA ligases, which comprise a superfamily of covalent nucleotidyl transferases defined by a constellation of conserved motifs. Analysis of the effects of motif VI mutations on Mce1 guanylyltransferase activity in vitro highlights essential roles for Arg530, Asp532, Lys533, and Asn537 in GTP binding and nucleotidyl transfer. |
| Keywords: | unclassified drug; nonhuman; protein conformation; protein domain; protein motif; mammalia; animals; amino acid substitution; enzyme degradation; enzyme activity; structure activity relation; mutational analysis; rna; dna; amino acid sequence; molecular sequence data; sequence homology, amino acid; species specificity; messenger rna; enzyme analysis; saccharomyces cerevisiae; eukaryota; crystal structure; models, molecular; mutagenesis, site-directed; yeast; catalysis; amino acids; enzyme kinetics; enzyme binding; enzyme structure; guanosine triphosphate; aspartic acid; mutagenesis; candida albicans; lysine; structure-activity relationships; glycine; arginine; asparagine; enzyme synthesis; chlorella virus; enzyme active site; enzyme; enzyme stability; nucleotidyltransferases; guanylyltransferase; chlorella; substitution reactions; priority journal; article; capping phenomenon; enzyme glycosylation |
| Journal Title: | Biochemistry |
| Volume: | 42 |
| Issue: | 27 |
| ISSN: | 0006-2960 |
| Publisher: | American Chemical Society |
| Date Published: | 2003-07-15 |
| Start Page: | 8240 |
| End Page: | 8249 |
| Language: | English |
| DOI: | 10.1021/bi034396d |
| PUBMED: | 12846573 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Export Date: 12 September 2014 -- Source: Scopus |
