Abstract
Cytoplasmic terminal uridylyl transferases comprise a conserved family of enzymes that negatively regulate the stability or biological activity of a variety of eukaryotic RNAs, including mRNAs and tumor-suppressor let-7 microRNAs. Here we describe crystal structures of the Schizosaccharomyces pombe cytoplasmic terminal uridylyl transferase Cid1 in two apo conformers and bound to UTP. We demonstrate that a single histidine residue, conserved in mammalian Cid1 orthologs, is responsible for discrimination between UTP and ATP. We also describe a new high-affinity RNA substrate-binding mechanism of Cid1, which is essential for enzymatic activity and is mediated by three basic patches across the surface of the enzyme. Overall, our structures provide a basis for understanding the activity of Cid1 and a mechanism of UTP selectivity conserved in its human orthologs, suggesting potential implications for anticancer drug design.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Apoenzymes / chemistry
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Apoenzymes / genetics
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Apoenzymes / metabolism
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Base Sequence
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Catalytic Domain
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Conserved Sequence
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Crystallography, X-Ray
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DNA Primers / genetics
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Humans
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Models, Molecular
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Nucleotidyltransferases / chemistry*
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Nucleotidyltransferases / genetics
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Nucleotidyltransferases / metabolism*
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Protein Conformation
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RNA, Fungal / metabolism
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Schizosaccharomyces / enzymology
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Schizosaccharomyces / genetics
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Schizosaccharomyces pombe Proteins / chemistry*
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Schizosaccharomyces pombe Proteins / genetics
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Schizosaccharomyces pombe Proteins / metabolism*
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Sequence Homology, Amino Acid
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Substrate Specificity
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Uridine Triphosphate / metabolism
Substances
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Apoenzymes
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DNA Primers
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RNA, Fungal
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Recombinant Proteins
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Schizosaccharomyces pombe Proteins
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Nucleotidyltransferases
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Cid1 protein, S pombe
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Uridine Triphosphate
Associated data
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PDB/4E7X
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PDB/4E80
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PDB/4E8F