1iq8
Crystal Structure of archaeosine tRNA-guanine transglycosylase from Pyrococcus horikoshii
| |||||||
| , resolution 2.2Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | and | ||||||
| Activity: | Queuine tRNA-ribosyltransferase, with EC number 2.4.2.29 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
OverviewOverview
Archaeosine tRNA-guanine transglycosylase (ArcTGT) catalyzes the exchange of guanine at position 15 in the D-loop of archaeal tRNAs with a free 7-cyano-7-deazaguanine (preQ(0)) base, as the first step in the biosynthesis of an archaea-specific modified base, archaeosine (7-formamidino-7-deazaguanosine). We determined the crystal structures of ArcTGT from Pyrococcus horikoshii at 2.2 A resolution and its complexes with guanine and preQ(0), at 2.3 and 2.5 A resolutions, respectively. The N-terminal catalytic domain folds into an (alpha/beta)(8) barrel with a characteristic zinc-binding site, showing structural similarity with that of the bacterial queuosine TGT (QueTGT), which is involved in queuosine (7-[[(4,5-cis-dihydroxy-2-cyclopenten-1-yl)-amino]methyl]-7-deazaguanosine ) biosynthesis and targets the tRNA anticodon. ArcTGT forms a dimer, involving the zinc-binding site and the ArcTGT-specific C-terminal domain. The C-terminal domains have novel folds, including an OB fold-like "PUA domain", whose sequence is widely conserved in eukaryotic and archaeal RNA modification enzymes. Therefore, the C-terminal domains may be involved in tRNA recognition. In the free-form structure of ArcTGT, an alpha-helix located at the rim of the (alpha/beta)(8) barrel structure is completely disordered, while it is ordered in the guanine-bound and preQ(0)-bound forms. Structural comparison of the ArcTGT.preQ(0), ArcTGT.guanine, and QueTGT.preQ(1) complexes provides novel insights into the substrate recognition mechanisms of ArcTGT.
About this StructureAbout this Structure
1IQ8 is a Single protein structure of sequence from Pyrococcus horikoshii. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of archaeosine tRNA-guanine transglycosylase., Ishitani R, Nureki O, Fukai S, Kijimoto T, Nameki N, Watanabe M, Kondo H, Sekine M, Okada N, Nishimura S, Yokoyama S, J Mol Biol. 2002 May 3;318(3):665-77. PMID:12054814
Page seeded by OCA on Thu Mar 20 11:53:26 2008