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| {{STRUCTURE_1it8| PDB=1it8 | SCENE= }} | | {{STRUCTURE_1it8| PDB=1it8 | SCENE= }} |
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| '''Crystal structure of archaeosine tRNA-guanine transglycosylase from Pyrococcus horikoshii complexed with archaeosine precursor, preQ0'''
| | ===Crystal structure of archaeosine tRNA-guanine transglycosylase from Pyrococcus horikoshii complexed with archaeosine precursor, preQ0=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12054814}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12054814 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12054814}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Rsgi]] | | [[Category: Rsgi]] |
| [[Category: Structural genomic]] | | [[Category: Structural genomic]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 20:23:11 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 13:57:39 2008'' |
