2gms

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spinqualitylabelsall models 2gms, resolution 1.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

E coli GDP-4-keto-6-deoxy-D-mannose-3-dehydratase with bound hydrated PLP

Overview

L-colitose is a 3,6-dideoxysugar found in the O-antigens of some, Gram-negative bacteria such as Escherichia coli and in marine bacteria, such as Pseudoalteromonas tetraodonis. The focus of this investigation, GDP-4-keto-6-deoxy-D-mannose-3-dehydratase, catalyzes the third step in, colitose production, which is the removal of the hydroxyl group at C3' of, GDP-4-keto-6-deoxymannose. It is an especially intriguing PLP-dependent, enzyme in that it acts as both a transaminase and a dehydratase. Here we, present the first X-ray structure of this enzyme isolated from E. coli, Strain 5a, type O55:H7. The two subunits of the protein form a tight dimer, with a buried surface area of approximately 5000 A2. This is a, characteristic feature of the aspartate aminotransferase superfamily., Although the PLP-binding pocket is formed primarily by one subunit, there, is a loop, delineated by Phe 240 to Glu 253 in the second subunit, that, completes the active site architecture. The hydrated form of PLP was, observed in one of the enzyme/cofactor complexes described here. Amino, acid residues involved in anchoring the cofactor to the protein include, Gly 56, Ser 57, Asp 159, Glu 162, and Ser 183 from one subunit and Asn 248, from the second monomer. In the second enzyme/cofactor complex reported, a, glutamate ketimine intermediate was found trapped in the active site., Taken together, these two structures, along with previously reported, biochemical data, support the role of His 188 as the active site base, required for catalysis.

About this Structure

2GMS is a Single protein structure of sequence from Escherichia coli with and as ligands. Full crystallographic information is available from OCA.

Reference

The structure of GDP-4-keto-6-deoxy-D-mannose-3-dehydratase: a unique coenzyme B6-dependent enzyme., Cook PD, Thoden JB, Holden HM, Protein Sci. 2006 Sep;15(9):2093-106. PMID:16943443

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