1uet
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Divergent evolutions of trinucleotide polymerization revealed by an archaeal CCA-adding enzyme structure
OverviewOverview
CCA-adding enzyme [ATP(CTP):tRNA nucleotidyltransferase], a, template-independent RNA polymerase, adds the defined, 'cytidine-cytidine-adenosine' sequence onto the 3' end of tRNA. The, archaeal CCA-adding enzyme (class I) and eubacterial/eukaryotic CCA-adding, enzyme (class II) show little amino acid sequence homology, but catalyze, the same reaction in a defined fashion. Here, we present the crystal, structures of the class I archaeal CCA-adding enzyme from Archaeoglobus, fulgidus, and its complexes with CTP and ATP at 2.0, 2.0 and 2.7 A, resolutions, respectively. The geometry of the catalytic carboxylates and, the relative positions of CTP and ATP to a single catalytic site are well, conserved in both classes of CCA-adding enzymes, whereas the overall, architectures, except for the catalytic core, of the class I and class II, CCA-adding enzymes are fundamentally different. Furthermore, the, recognition mechanisms of substrate nucleotides and tRNA molecules are, distinct between these two classes, suggesting that the catalytic domains, of class I and class II enzymes share a common origin, and distinct, substrate recognition domains have been appended to form the two presently, divergent classes.
About this StructureAbout this Structure
1UET is a Single protein structure of sequence from Archaeoglobus fulgidus with ACT, CA and MG as ligands. Active as tRNA adenylyltransferase, with EC number 2.7.7.25 Full crystallographic information is available from OCA.
ReferenceReference
Divergent evolutions of trinucleotide polymerization revealed by an archaeal CCA-adding enzyme structure., Okabe M, Tomita K, Ishitani R, Ishii R, Takeuchi N, Arisaka F, Nureki O, Yokoyama S, EMBO J. 2003 Nov 3;22(21):5918-27. PMID:14592988
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