2fxv

Bacillus subtilis Xanthine Phosphoribosyltransferase in Complex with Guanosine 5'-monophosphate (GMP)

spinqualitylabelsall models 2fxv, resolution 2.05Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2fxv is a 2 chain structure with sequence from Bacillus subtilis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.05Å Ligands: 5GP, GOL Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function XPT_BACSU Converts the preformed base xanthine, a product of nucleic acid breakdown, to xanthosine 5'-monophosphate (XMP), so that it can be reused for RNA or DNA synthesis.[HAMAP-Rule:MF_01184] 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 Xanthine phosphoribosyltransferase (XPRTase) from Bacillus subtilis is a representative of the highly xanthine specific XPRTases found in Gram-positive bacteria. These XPRTases constitute a distinct subclass of 6-oxopurine PRTases, which deviate strongly from the major class of H(X)GPRTases with respect to sequence, PRPP binding motif, and oligomeric structure. They are more related with the PurR repressor of Gram-positive bacteria, the adenine PRTase, and orotate PRTase. The catalytic function and high specificity for xanthine of B. subtilis XPRTase were investigated by ligand binding studies and reaction kinetics as a function of pH with xanthine, hypoxanthine, and guanine as substrates. The crystal structure of the dimeric XPRTase-GMP complex was determined to 2.05 A resolution. In a sequential reaction mechanism XPRTase binds first PRPP, stabilizing its active dimeric form, and subsequently xanthine. The XPRTase is able also to react with guanine and hypoxanthine albeit at much lower (10(-)(4)-fold) catalytic efficiency. Different pK(a) values for the bases and variations in their electrostatic potential can account for these catalytic differences. The unique base specificity of XPRTase has been related to a few key residues in the active site. Asn27 can in different orientations form hydrogen bonds to an amino group or an oxo group at the 2-position of the purine base, and Lys156 is positioned to make a hydrogen bond with N7. This and the absence of a catalytic carboxylate group near the N7-position require the purine base to dissociate a proton spontaneously in order to undergo catalysis. The extraordinary specificity of xanthine phosphoribosyltransferase from Bacillus subtilis elucidated by reaction kinetics, ligand binding, and crystallography.,Arent S, Kadziola A, Larsen S, Neuhard J, Jensen KF Biochemistry. 2006 May 30;45(21):6615-27. PMID:16716072 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Phosphoribosyltransferase 3D structures

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