4WC4: Trna-processing Enzyme Complex 2

The 3'-terminal CCA (C74C75A76-3') of tRNA is required for protein synthesis. In Aquifex aeolicus, the CCA-3' is synthesized by CC-adding and A-adding enzymes, although in most organisms, CCA is synthesized by a single CCA-adding enzyme. The mechanisms by which the A-adding enzyme adds only A76, but not C74C75, onto tRNA remained elusive. The complex structures of the enzyme with various tRNAs revealed the presence of a single tRNA binding site on the enzyme, with the enzyme measuring the acceptor-TPsiC helix length of tRNA. The 3'-C75 of tRNA lacking A76 can reach the active site and the size and shape of the nucleotide binding pocket at the insertion stage are suitable for ATP. The 3'-C74 of tRNA lacking C75A76 cannot reach the active site, although CTP or ATP can bind the active pocket. Thus, the A-adding enzyme adds only A76, but not C74C75, onto tRNA.
PDB ID: 4WC4Download
MMDB ID: 128637
PDB Deposition Date: 2014/9/4
Updated in MMDB: 2015/05
Experimental Method:
x-ray diffraction
Resolution: 3.5  Å
Source Organism:
Thermotoga maritima MSB8
Similar Structures:
Biological Unit for 4WC4: dimeric; determined by author
Molecular Components in 4WC4
Label Count Molecule
Protein (1 molecule)
Poly a Polymerase
Molecule annotation
Nucleotide(1 molecule)
RNA (74-mer)
Molecule annotation
Chemical (1 molecule)
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Citing MMDB