1jcy
From Proteopedia
| |||||||
| , resolution 1.90Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , , , | ||||||
| Activity: | 3-deoxy-8-phosphooctulonate synthase, with EC number 2.5.1.55 | ||||||
| Related: | 1FWW, 1JCX
| ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Aquifex aeolicus KDO8P synthase in complex with R5P, PEP and Cadmium
Overview
We have determined the crystal structures of the metalloenzyme 3-deoxy-D-manno-octulosonate 8-phosphate (KDO8P) synthase from Aquifex aeolicus in complex with phosphoenolpyruvate (PEP) and ribose 5-phosphate (R5P), and with a bisubstrate inhibitor that mimics the postulated linear reaction intermediate. R5P, which is not a substrate for KDO8P synthase, binds in a manner similar to that of arabinose 5-phosphate (A5P), which is the natural substrate. The lack of reactivity of R5P appears to be primarily a consequence of the loss of a water molecule coordinated to Cd(2+) and located on the si side of PEP. This water molecule is no longer present because it cannot form a hydrogen bond with C2-OH(R5P), which is oriented in a different direction from C2-OH(A5P). The bisubstrate inhibitor binds with its phosphate and phosphonate moieties occupying the positions of the phosphate groups of A5P and PEP, respectively. One of the inhibitor hydroxyls replaces water as a ligand of Cd(2+). The current work supports a mechanism for the synthesis of KDO8P, in which a hydroxide ion on the si side of PEP attacks C2(PEP), forming a tetrahedral-like intermediate with a buildup of negative charge at C3(PEP). The ensuing condensation of C3(PEP) with C1(A5P) would be favored by a proton transfer from the phosphate moiety of PEP to the aldehyde carbonyl of A5P to generate the hydroxyl. Overall, the process can be described as a syn addition of water and A5P to the si side of PEP.
About this Structure
1JCY is a Single protein structure of sequence from Aquifex aeolicus. Full crystallographic information is available from OCA.
Reference
Structures of Aquifex aeolicus KDO8P synthase in complex with R5P and PEP, and with a bisubstrate inhibitor: role of active site water in catalysis., Wang J, Duewel HS, Woodard RW, Gatti DL, Biochemistry. 2001 Dec 25;40(51):15676-83. PMID:11747443
Page seeded by OCA on Sun Mar 30 21:31:49 2008
