Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Escherichia coli [ICD11:
XN6P4 
]
NCBI PubMed ID: 18045869Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: Hazel_Holden
biochem.wisc.edu
Institutions: Department of Biochemistry, University of Wisconsin, Madison, WI, USA
Colitose is a dideoxysugar found in the O-antigen of the lipopolysaccharide that coats the outer membrane of some Gram-negative bacteria. Four enzymes are required for its production starting from D-mannose-1-phosphate and GTP. The focus of this investigation is GDP-4-keto-6-deoxy-D-mannose-3-dehydratase or ColD, which catalyzes the removal of the C3'-hydroxyl group from GDP-4-keto-6-deoxymannose. The enzyme is PLP-dependent, but unlike most of these proteins, the conserved lysine residue which covalently holds the cofactor in the active site is replaced with a histidine residue. Here we describe the three-dimensional structure of ColD determined to 1.7 A resolution whereby the active site histidine has been replaced with an asparagine residue. For this investigation, crystals of the site-directed mutant protein were grown in the presence of GDP-4-amino-4,6-dideoxy-D-mannose (GDP-perosamine). The electron density map clearly reveals the presence of the sugar analog trapped in the active site as an external aldimine. The active site is positioned between the two subunits of the dimer. Whereas the pyrophosphoryl groups of the ligand are anchored to the protein via Arg 219 and Arg 331, the hydroxyl groups of the hexose only lie within hydrogen bonding distance to ordered water molecules. Interestingly, the hexose moiety of the ligand adopts a boat rather than the typically observed chair conformation. Activity assays demonstrate that this mutant protein cannot catalyze the dehydration step. Additionally, we report data revealing that wild-type ColD is able to catalyze the production of GDP-4-keto-3,6-dideoxy-mannose using GDP-perosamine instead of GDP-4-keto-6-deoxymannose as a substrate.
Enzymes, colitose, ColD, dehydratase
Structure type: monomer
Location inside paper: p.4296, scheme 1
Trivial name: componente of O-antigen, D-mannose-1-phosphate
Contained glycoepitopes: IEDB_130701,IEDB_144983,IEDB_144996,IEDB_152206,IEDB_983930,SB_44,SB_67,SB_72
Methods: X-ray, sugar analysis, ESI-MS, genetic methods, biochemical methods, HPLC, crystallization
Biological activity: biological activity data
Biosynthesis and genetic data: genetic data
3D data: molecular modeling, 3D data
Related record ID(s): 20067, 22869, 22876, 22877, 22878, 22879, 22880, 23106, 23919
NCBI Taxonomy refs (TaxIDs): 244320Reference(s) to other database(s): GlycomeDB:
471
Show glycosyltransferases
There is only one chemically distinct structure:
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