2bbf

Crystal structure of tRNA-guanine transglycosylase (TGT) from Zymomonas mobilis in complex with 6-amino-3,7-dihydro-imidazo[4,5-g]quinazolin-8-one

spinqualitylabelsall models 2bbf, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2bbf is a 1 chain structure with sequence from Zymomonas mobilis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.7Å Ligands: 344, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TGT_ZYMMO Exchanges the guanine residue with 7-aminomethyl-7-deazaguanine in tRNAs with GU(N) anticodons (tRNA-Asp, -Asn, -His and -Tyr). After this exchange, a cyclopentendiol moiety is attached to the 7-aminomethyl group of 7-deazaguanine, resulting in the hypermodified nucleoside queuosine (Q) (7-(((4,5-cis-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-7-deazaguanosine).[HAMAP-Rule:MF_00168] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The bacterial tRNA-guanine transglycosylase (TGT) is a tRNA modifying enzyme catalyzing the exchange of guanine 34 by the modified base preQ1. The enzyme is involved in the infection pathway of Shigella, causing bacterial dysentery. As no crystal structure of the Shigella enzyme is available the homologous Zymomonas mobilis TGT was used for structure-based drug design resulting in new, potent, lin-benzoguanine-based inhibitors. Thorough kinetic studies show size-dependent inhibition of these compounds resulting in either a competitive or non-competitive blocking of the base exchange reaction in the low micromolar range. Four crystal structures of TGT-inhibitor complexes were determined with a resolution of 1.58-2.1 A. These structures give insight into the structural flexibility of TGT necessary to perform catalysis. In three of the structures molecular rearrangements are observed that match with conformational changes also noticed upon tRNA substrate binding. Several water molecules are involved in these rearrangement processes. Two of them demonstrate the structural and catalytic importance of water molecules during TGT base exchange reaction. In the fourth crystal structure the inhibitor unexpectedly interferes with protein contact formation and crystal packing. In all presently known TGT crystal structures the enzyme forms tightly associated homodimers internally related by crystallographic symmetry. Upon binding of the fourth inhibitor the dimer interface, however, becomes partially disordered. This result prompted further analyses to investigate the relevance of dimer formation for the functional protein. Consultation of the available TGT structures and sequences from different species revealed structural and functional conservation across the contacting residues. This suggests that bacterial and eukaryotic TGT could possibly act as homodimers in catalysis. It is hypothesized that one unit of the dimer performs the catalytic reaction whereas the second is required to recognize and properly orient the bound tRNA for the catalytic reaction. Crystal structures of tRNA-guanine transglycosylase (TGT) in complex with novel and potent inhibitors unravel pronounced induced-fit adaptations and suggest dimer formation upon substrate binding.,Stengl B, Meyer EA, Heine A, Brenk R, Diederich F, Klebe G J Mol Biol. 2007 Jul 13;370(3):492-511. Epub 2007 Apr 12. PMID:17524419 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also TRNA-guanine transglycosylase 3D structures

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