2FXV

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

2FXV の概要

• エントリーDOI: 10.2210/pdb2fxv/pdb
• 分子名称: Xanthine phosphoribosyltransferase, GUANOSINE-5'-MONOPHOSPHATE, GLYCEROL, ... (4 entities in total)
• 機能のキーワード: type 1 phosphoribosyltransferase, gmp complex, transferase
• 由来する生物種: Bacillus subtilis
• 細胞内の位置: Cytoplasm (Potential): P42085
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 42946.82

構造登録者

Arent, S.,Kadziola, A.,Larsen, S.,Neuhard, J.,Jensen, K.F. (登録日: 2006-02-06, 公開日: 2006-06-20, 最終更新日: 2023-10-25)

主引用文献

Arent, S.,Kadziola, A.,Larsen, S.,Neuhard, J.,Jensen, K.F.
The Extraordinary Specificity of Xanthine Phosphoribosyltransferase from Bacillus subtilis Elucidated by Reaction Kinetics, Ligand Binding, and Crystallography
Biochemistry, 45:6615-6627, 2006

PubMed Abstract: 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.

PubMed: 16716072
DOI: 10.1021/bi060287y

実験手法

X-RAY DIFFRACTION (2.05 Å)