1OU5

Crystal structure of human CCA-adding enzyme

Summary for 1OU5

• Entry DOI: 10.2210/pdb1ou5/pdb
• Related: 1MIV 1MIW 1MIY
• Descriptor: tRNA CCA-adding enzyme (1 entity in total)
• Functional Keywords: trna, polymerase, nucleotidyltransferase, translation, transferase
• Biological source: Homo sapiens (human)
• Cellular location: Mitochondrion : Q96Q11
• Total number of polymer chains: 2
• Total formula weight: 102450.29

Authors

Augustin, M.A.,Reichert, A.S.,Betat, H.,Huber, R.,Moerl, M.,Steegborn, C. (deposition date: 2003-03-24, release date: 2003-05-06, Last modification date: 2024-10-30)

Primary citation

Augustin, M.A.,Reichert, A.S.,Betat, H.,Huber, R.,Moerl, M.,Steegborn, C.
Crystal Structure of the Human CCA-adding Enzyme: Insights into Template-independent Polymerization
J.Mol.Biol., 328:985-994, 2003

PubMed Abstract: All tRNA molecules carry the invariant sequence CCA at their 3'-terminus for amino acid attachment. The post-transcriptional addition of CCA is carried out by ATP(CTP):tRNA nucleotidyltransferase, also called CCase. This enzyme catalyses a unique template-independent but sequence-specific nucleotide polymerization reaction. In order to reveal the molecular mechanism of this activity, we solved the crystal structure of human CCase by single isomorphous replacement. The structure reveals a four domain architecture with a cluster of conserved residues forming a positively charged cleft between the first two domains. Structural homology of the N-terminal CCase domain to other nucleotidyltransferases could be exploited for modeling a tRNA-substrate complex. The model places the tRNA 3'-end into the N-terminal nucleotidyltransferase site, close to a patch of conserved residues that provide the binding sites for CTP and ATP. Based on our results, we introduce a corkscrew model for CCA addition that includes a fixed active site and a traveling tRNA-binding region formed by flexible parts of the protein.

PubMed: 12729736
DOI: 10.1016/S0022-2836(03)00381-4

Experimental method

X-RAY DIFFRACTION (3.4 Å)