1r8c
Crystal Structures of an Archaeal Class I CCA-Adding Enzyme and Its NucleotideCrystal Structures of an Archaeal Class I CCA-Adding Enzyme and Its Nucleotide
Structural highlights
Function[CCA_ARCFU] Catalyzes the addition and repair of the essential 3'-terminal CCA sequence in tRNAs without using a nucleic acid template. Adds these three nucleotides in the order of C, C, and A to the tRNA nucleotide-73, using CTP and ATP as substrates and producing inorganic pyrophosphate.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedCCA-adding enzymes catalyze the addition of CCA onto the 3' terminus of immature tRNAs without using a nucleic acid template and have been divided into two classes based on their amino acid sequences. We have determined the crystal structures of a class I CCA-adding enzyme from Archeoglobus fulgidus (AfCCA) and its complexes with ATP, CTP, or UTP. Although it and the class II bacterial Bacillus stearothermophilus CCA enzyme (BstCCA) have similar dimensions and domain architectures (head, neck, body, and tail), only the polymerase domain is structurally homologous. Moreover, the relative orientation of the head domain with respect to the body and tail domains, which appear likely to bind tRNA, differs significantly between the two enzyme classes. Unlike the class II BstCCA, this enzyme binds nucleotides nonspecifically in the absence of bound tRNA. The shape and electrostatic charge distribution of the AfCCA enzyme suggests a model for tRNA binding that accounts for the phosphates that are protected from chemical modification by tRNA binding to AfCCA. The structures of the AfCCA enzyme and the eukaryotic poly(A) polymerase are very similar, implying a close evolutionary relationship between them. Crystal structures of an archaeal class I CCA-adding enzyme and its nucleotide complexes.,Xiong Y, Li F, Wang J, Weiner AM, Steitz TA Mol Cell. 2003 Nov;12(5):1165-72. PMID:14636575[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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