Crystal Structure of Archaeosine tRNA-guanine Transglycosylase

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• 作者：Ishitani ; Ryuichiro ; Nureki ; Osamu ; Fukai ; Shuya ; Kijimoto ; Teiya ; Nameki ; Nobukazu ; Watanabe ; Masakatsu ; et. al.
• 关键词：archaea ; archaeosine ; tRNA-guanine transglycosylase ; tRNA modification ; 7-cyano-7-deazaguanine ; Q ; queuosine (7-{[(4 ; 5-cis-dihydroxy-2-cyclopenten-1-yl)-amino]methyl}-7-deazaguanosine) ; ArcTGT ; archaeosine tRNA-guanine transglycosylase ; QueTGT ; queuosine
• 刊名：Journal of Molecular Biology
• 出版年：2002
• 出版时间：May 3, 2002
• 年：2002
• 卷：318
• 期：3
• 页码：665-677
• 全文大小：1.85 M

文摘

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 (preQ₀) 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 2.2Å resolution and its complexes with guanine and preQ₀, at 2.3 and 2.5Å resolutions, respectively. The N-terminal catalytic domain folds into an (α/β)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.