EC Number   |
General Information |
Reference |
|---|
   2.7.7.72 | evolution |
a class I CCA-adding enzyme. CCA-adding enzymes are essential RNA polymerases that emerged twice in evolution leading to different structural characteristics and unusual mechanistic solutions for an error-free and sequence-specific CCA polymerization reaction. The catalytic cleft is formed by the head, neck, and body domains. Evolution of class I and class II CCA-adding enzymes as well as poly(A) polymerases, overview |
721997 |
| 2.7.7.72 | evolution |
a class II CCA-adding enzyme. Compared to class I, class II CCA-adding enzymes show a much higher evolutionary conservation of individual catalytic core motifs. Evolution of class I and class II CCA-adding enzymes as well as poly(A) polymerases, overview |
721997 |
| 2.7.7.72 | evolution |
a class II CCA-adding enzyme. Compared to class I, class II CCA-adding enzymes show a much higher evolutionary conservation of individual catalytic core motifs. The templating motif carries the sequence DDxxR, a slight deviation from the usual EDxxR motif. Evolution of class I and class II CCA-adding enzymes as well as poly(A) polymerases, overview |
721997 |
| 2.7.7.72 | evolution |
CCA-adding enzymes are essential RNA polymerases that emerged twice in evolution leading to different structural characteristics and unusual mechanistic solutions for an error-free and sequence-specific CCA polymerization reaction. Evolution of class I and class II CCA-adding enzymes as well as poly(A) polymerases, overview |
721997 |
| 2.7.7.72 | evolution |
diphosphorolysis of class II enzymes establishes a fundamental difference from class I enzymes, and it is achieved only with the tRNA structure and with specific divalent metal ions |
722982 |
| 2.7.7.72 | evolution |
with a possible origin of ancient telomerase-like activity, the CCA-adding enzymes obviously emerged twice during evolution, leading to structurally different, but functionally identical enzymes. While the enzyme class 1 is exclusively found in archaea, class 2 tRNA-nucleotidyltransferases are present in eukaryotes and bacteria. Class 1 enzymes have a tRNA-binding body domain consisting of a beta sheet with flanking alpha helices. Head and neck domains form the active site and are also composed of alpha-helical and beta-sheet elements. The chemical mechanism underlying the polymerization appears conserved in all polymerases across the three kingdoms of life |
722263 |
| 2.7.7.72 | evolution |
with a possible origin of ancient telomerase-like activity, the CCA-adding enzymes obviously emerged twice during evolution, leading to structurally different, but functionally identical enzymes. While the enzyme class 1 is exclusively found in archaea, class 2 tRNA-nucleotidyltransferases are present in eukaryotes and bacteria. In class 2 enzymes, only the head domain carries a beta sheet and forms the nucleotidyltransferase core, while neck, body and tail consist exclusively of alpha helices, giving the enzyme a hook- or seahorse-like overall structure. The chemical mechanism underlying the polymerization appears conserved in all polymerases across the three kingdoms of life |
722263 |
| 2.7.7.72 | malfunction |
CCA ends with misincorporated nucleotides are only rarely detected. Only under rather artificial in vitro conditions, e.g. in the presence of Mn2+ ions instead of Mg2+ or deviating NTP concentrations, incorporation of CCC as well as poly(C) tails can be observed |
722263 |
| 2.7.7.72 | malfunction |
mutations around the active site of the Sulfolobus shibatae enzyme interfere with CCA-addition, but have only a minor affect on tRNA binding |
721997 |
| 2.7.7.72 | malfunction |
the enzyme knockout phenotype is a dramatic growth impairment, indicating the repair function of the CCA-adding enzyme on defective tRNAs lacking CCA ends due to hydrolytic damage |
721997 |
