منابع مشابه
Divergent evolutions of trinucleotide polymerization revealed by an archaeal CCA-adding enzyme structure.
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 crysta...
متن کاملCrystal structures of an archaeal class I CCA-adding enzyme and its nucleotide complexes.
CCA-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...
متن کاملOn the role of a conserved, potentially helix-breaking residue in the tRNA-binding alpha-helix of archaeal CCA-adding enzymes.
Archaeal class I CCA-adding enzymes use a ribonucleoprotein template to build and repair the universally conserved 3'-terminal CCA sequence of the acceptor stem of all tRNAs. A wealth of structural and biochemical data indicate that the Archaeoglobus fulgidus CCA-adding enzyme binds primarily to the tRNA acceptor stem through a long, highly conserved alpha-helix that lies nearly parallel to the...
متن کاملUnusual evolution of a catalytic core element in CCA-adding enzymes
CCA-adding enzymes are polymerases existing in two distinct enzyme classes that both synthesize the C-C-A triplet at tRNA 3'-ends. Class II enzymes (found in bacteria and eukaryotes) carry a flexible loop in their catalytic core required for switching the specificity of the nucleotide binding pocket from CTP- to ATP-recognition. Despite this important function, the loop sequence varies strongly...
متن کاملReengineering CCA-adding enzymes to function as (U,G)- or dCdCdA-adding enzymes or poly(C,A) and poly(U,G) polymerases.
CCA-adding enzymes build and repair the 3'-terminal CCA sequence of tRNA. These unusual RNA polymerases use either a ribonucleoprotein template (class I) or pure protein template (class II) to form mock base pairs with the Watson-Crick edges of incoming CTP and ATP. Guided by the class II Bacillus stearothermophilus CCA-adding enzyme structure, we introduced mutations designed to reverse the po...
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ژورنال
عنوان ژورنال: Journal of Biological Chemistry
سال: 2005
ISSN: 0021-9258
DOI: 10.1074/jbc.m412594200