Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Campylobacter jejuni [ICD11:
XN4Q5 
]
NCBI PubMed ID: 32168450Publication DOI: 10.1021/acs.biochem.0c00096Journal NLM ID: 0370623Publisher: American Chemical Society
Correspondence: hmholden
wisc.edu; raushel
tamu.edu
Institutions: Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States, Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas 77843, United States, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
Many strains of Campylobacter jejuni display modified heptose residues in their capsular polysaccharides (CPS). The precursor heptose was previously shown to be GDP-d-glycero-α-d-manno-heptose, from which a variety of modifications of the sugar moiety have been observed. These modifications include the generation of 6-deoxy derivatives and alterations of the stereochemistry at C3-C6. Previous work has focused on the enzymes responsible for the generation of the 6-deoxy derivatives and those involved in altering the stereochemistry at C3 and C5. However, the generation of the 6-hydroxyl heptose residues remains uncertain due to the lack of a specific enzyme to catalyze the initial oxidation at C4 of GDP-d-glycero-α-d-manno-heptose. Here we reexamine the previously reported role of Cj1427, a dehydrogenase found in C. jejuni NTCC 11168 (HS:2). We show that Cj1427 is co-purified with bound NADH, thus hindering catalysis of oxidation reactions. However, addition of a co-substrate, α-ketoglutarate, converts the bound NADH to NAD+. In this form, Cj1427 catalyzes the oxidation of l-2-hydroxyglutarate back to α-ketoglutarate. The crystal structure of Cj1427 with bound GDP-d-glycero-α-d-manno-heptose shows that the NAD(H) cofactor is ideally positioned to catalyze the oxidation at C4 of the sugar substrate. Additionally, the overall fold of the Cj1427 subunit places it into the well-defined short-chain dehydrogenase/reductase superfamily. The observed quaternary structure of the tetrameric enzyme, however, is highly unusual for members of this superfamily.
biosynthesis, heptose, capsular polysaccharide, Campylobacter jejuni, structural analysis, crystal structure, modification, oxidation, dehydrogenase
Structure type: polymer chemical repeating unit
Location inside paper: p.1315, scheme 1
Compound class: CPS
Contained glycoepitopes: IEDB_115136,IEDB_137473,IEDB_140630,IEDB_149136
Methods: X-ray, biochemical methods, UV, FPLC, cloning, crystallization, computational docking
NCBI Taxonomy refs (TaxIDs): 197
Show glycosyltransferases
There is only one chemically distinct structure:
Found 
report error