Characterization of Candida albicans RNA triphosphatase and mutational analysis of its active site Journal Article
| Authors: | Pei, Y.; Lehman, K.; Tian, L.; Shuman, S. |
| Article Title: | Characterization of Candida albicans RNA triphosphatase and mutational analysis of its active site |
| Abstract: | The RNA triphosphatase component (CaCet1p) of the mRNA capping apparatus of the pathogenic fungus Candida albicans differs mechanistically and structurally from the RNA triphosphatase of mammals. Hence, CaCet1p is an attractive antifungal target. Here we identify a C-terminal catalytic domain of CaCet1p from residue 257 to 520 and characterize a manganese-dependent and cobalt-dependent NTPase activity intrinsic to CaCet1p. The NTPase can be exploited to screen in vitro for inhibitors. The amino acids that comprise the active site of CaCet1p were identified by alanine-scanning mutagenesis, which was guided by the crystal structure of the homologous RNA triphosphatase from Saccharomyces cerevisiae (Cet1p). Thirteen residues required for the phosphohydrolase activity of CaCet1p (Glu287, Glu289, Asp363, Arg379, Lys396, Glu420, Arg441, Lys443, Arg445, Asp458, Glu472, Glu474 and Glu476) are located within the hydrophilic interior of an eight-strand β barrel of Cet1p. Each of the eight strands contributes at least one essential amino acid. The essential CaCet1p residues include all of the side chains that coordinate manganese and sulfate (i.e., γ phosphate) in the Cet1p product complex. These results suggest that the active site structure and catalytic mechanism are conserved among fungal RNA triphosphatases. |
| Keywords: | gene mutation; mutation; sequence deletion; nonhuman; mammalia; phosphatase; carboxy terminal sequence; acid anhydride hydrolases; structure-activity relationship; amino acid sequence; molecular sequence data; sequence homology, amino acid; kinetics; messenger rna; saccharomyces cerevisiae; escherichia coli; recombinant proteins; crystal structure; protein structure, tertiary; binding sites; alanine; adenosine triphosphate; cobalt; protein secondary structure; sequence homology; glutamic acid; phosphates; hydrolysis; aspartic acid; candida albicans; fungi; lysine; arginine; enzyme active site; gene expression regulation, enzymologic; hydrophilicity; rna capping; manganese; sulfate; fungal rna; priority journal; article |
| Journal Title: | Nucleic Acids Research |
| Volume: | 28 |
| Issue: | 9 |
| ISSN: | 0305-1048 |
| Publisher: | Oxford University Press |
| Date Published: | 2000-05-01 |
| Start Page: | 1885 |
| End Page: | 1892 |
| Language: | English |
| PUBMED: | 10756187 |
| PROVIDER: | scopus |
| PMCID: | PMC103306 |
| DOI: | 10.1093/nar/28.9.1885 |
| DOI/URL: | |
| Notes: | Export Date: 18 November 2015 -- Source: Scopus |
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