3au7

Publication Abstract from PubMed

The cytidine at the first position of the anticodon (C34) in the AUA codon-specific archaeal tRNA(Ile2) is modified to 2-agmatinylcytidine (agm(2)C or agmatidine), an agmatine-conjugated cytidine derivative, which is crucial for the precise decoding of the genetic code. Agm(2)C is synthesized by tRNA(Ile)-agm(2)C synthetase (TiaS) in an ATP-dependent manner. Here we present the crystal structures of the Archaeoglobus fulgidus TiaS-tRNA(Ile2) complexed with ATP, or with AMPCPP and agmatine, revealing a previously unknown kinase module required for activating C34 by phosphorylation, and showing the molecular mechanism by which TiaS discriminates between tRNA(Ile2) and tRNA(Met). In the TiaS-tRNA(Ile2)-ATP complex, C34 is trapped within a pocket far away from the ATP-binding site. In the agmatine-containing crystals, C34 is located near the AMPCPP gamma-phosphate in the kinase module, demonstrating that agmatine is essential for placing C34 in the active site. These observations also provide the structural dynamics for agm(2)C formation.

Structural basis of tRNA agmatinylation essential for AUA codon decoding.,Osawa T, Kimura S, Terasaka N, Inanaga H, Suzuki T, Numata T Nat Struct Mol Biol. 2011 Oct 16;18(11):1275-80. doi: 10.1038/nsmb.2144. PMID:22002223^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.