PDBsum entry 4wc5

Transferase/RNA

PDB id: 4wc5

Contents

Protein chain

367 a.a.

DNA/RNA

Ligands

CTP

References listed in PDB file

Key reference

• Title: Measurement of acceptor-TΨc helix length of tRNA for terminal a76-Addition by a-Adding enzyme.
• Authors: S.Yamashita, A.Martinez, K.Tomita.
• Ref.: Structure, 2015, 23, 830-842. [DOI no: 10.1016/j.str.2015.03.013]
• PubMed id: 25914059

Abstract

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-TΨC 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.