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Divergent evolutions of trinucleotide polymerization revealed by an archaeal CCA‐adding enzyme structure
Author(s) -
Okabe Mayuko,
Tomita Kozo,
Ishitani Ryuichiro,
Ishii Ryohei,
Takeuchi o,
Arisaka Fumio,
Nureki Osamu,
Yokoyama Shigeyuki
Publication year - 2003
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdg563
Subject(s) - biology , genetics , enzyme , polymerization , evolutionary biology , computational biology , biochemistry , polymer , chemistry , organic chemistry
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 Å 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.