2cgk
From Proteopedia
CRYSTAL STRUCTURE OF L-RHAMNULOSE KINASE FROM ESCHERICHIA COLI IN AN OPEN UNCOMPLEXED CONFORMATION.
Overview
Bacterial L-rhamnulose kinase participates in the degradation of L-rhamnose, which is ubiquitous and particularly abundant in some plants. The enzyme catalyzes the transfer of the gamma-phosphate group from ATP to the 1-hydroxyl group of L-rhamnulose. We determined the crystal structures of the substrate-free kinase and of a complex between the enzyme, ADP and L-fructose, which besides rhamnulose is also processed. According to its chainfold, the kinase belongs to the hexokinase-hsp70-actin superfamily. The closest structurally known homologue is glycerol kinase. The reported structures reveal a large conformational change on substrate binding as well as the key residues involved in catalysis. The substrates ADP and beta-L-fructose are in an ideal position to define a direct in-line phosphoryl transfer through a bipyramidal pentavalent intermediate. The enzyme contains one disulfide bridge at a position where two homologous glycerol kinases are regulated by phosphorylation and effector binding, respectively, and it has two more pairs of cysteine residues near the surface that are poised for bridging. However, identical catalytic rates were observed for the enzyme in reducing and oxidizing environments, suggesting that regulation by disulfide formation is unlikely.
About this Structure
2CGK is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Structure and reaction mechanism of L-rhamnulose kinase from Escherichia coli., Grueninger D, Schulz GE, J Mol Biol. 2006 Jun 9;359(3):787-97. Epub 2006 Apr 25. PMID:16674975 Page seeded by OCA on Sat May 3 22:05:16 2008
