to the wild-type enzyme RgDAAO, leading to a mutant Zn7 with greater than 2000-fold improvement in specific activity toward the unnatural substrate D-glufosinate, which was converted into PPO, a precursor of an excellent herbicide, L-PPT. Computational analysis revealed that the higher activity was mainly caused by an extended reaction pocket with greater hydrophilicity.
Crystal Structure of the ATPPase Subunit and Its Substrate-Dependent Association with the GATase Subunit: A Novel Regulatory Mechanism for a Two-Subunit-Type GMP Synthetase from Pyrococcus horikoshii OT3
Guanosine 5'-monophosphate synthetase(s) (GMPS) catalyzes the final step of the de novo synthetic pathway of purine nucleotides. GMPS consists of two functional units that are present as domains or subunits: glutamine amidotransferase (GATase) and ATP pyrophosphatase (ATPPase). GATase hydrolyzes glutamine to yield glutamate and ammonia, while ATPPase utilizes ammonia to convert adenyl xanthosine 5'-monophosphate (adenyl-XMP) into guanosine 5'-monophosphate. Here we report the crystal structure of PH-ATPPase (the ATPPase subunit of the two-subunit-type GMPS from the hyperthermophilic archaeon Pyrococcus horikoshii OT3). PH-ATPPase consists of two domains (N-domain and C-domain) and exists as a homodimer in the crystal and in solution. The N-domain contains an ATP-binding platform called P-loop, whereas the C-domain contains the xanthosine 5'-monophosphate (XMP)-binding site and also contributes to homodimerization. We have also demonstrated that PH-GATase (the glutamine amidotransferase subunit of the two-subunit-type GMPS from the hyperthermophilic archaeon P. horikoshii OT3) alone is inactive, and that all substrates of PH-ATPPase except for ammonia (Mg2+, ATP and XMP) are required to stabilize the active complex of PH-ATPPase and PH-GATase subunits. (C) 2009 Elsevier Ltd. All rights reserved.
Waelsch, 1952, vol. 13, p. 282 - 284
作者:Waelsch
DOI:——
日期:——
Meister in S.P. Colowick; N.O.Kaplan, Methods in Enzymology,Bd.2<New York 1955>S.380
作者:Meister in S.P. Colowick、N.O.Kaplan
DOI:——
日期:——
Varner in P.D.Boyer; H.Lardy; K.Myrbaeck, The Enzymes,Bd.4 <New York 1960>S.244