Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Escherichia coli [ICD11:
XN6P4 
]
NCBI PubMed ID: 22217153Publication DOI: 10.1021/bi201820pJournal NLM ID: 0370623Publisher: American Chemical Society
Correspondence: kiessling
chem.wisc.edu
Institutions: Department of Biochemistry, University of Wisconsin, Madison, WI, USA
Even in the absence of a template, glycosyltransferases can catalyze the synthesis of carbohydrate polymers of specific sequence. The paradigm has been that one enzyme catalyzes the formation of one type of glycosidic linkage, yet certain glycosyltransferases generate polysaccharide sequences composed of two distinct linkage types. In principle, bifunctional glycosyltransferases can possess separate active sites for each catalytic activity or one active site with dual activities. We encountered the fundamental question of one or two distinct active sites in our investigation of the galactosyltransferase GlfT2. GlfT2 catalyzes the formation of mycobacterial galactan, a critical cell-wall polymer composed of galactofuranose residues connected with alternating, regioisomeric linkages. We found that GlfT2 mediates galactan polymerization using only one active site that manifests dual regioselectivity. Structural modeling of the bifunctional glycosyltransferases hyaluronan synthase and cellulose synthase suggests that these enzymes also generate multiple glycosidic linkages using a single active site. These results highlight the versatility of glycosyltransferases for generating polysaccharides of specific sequence. We postulate that a hallmark of processive elongation of a carbohydrate polymer by a bifunctional enzyme is that one active site can give rise to two separate types of glycosidic bonds.
glycosyltransferases, Substrate Specificity, galactosyltransferase, Galactan, modeling, hyaluronan, polymerization
Structure type: polymer chemical repeating unit
Location inside paper: p.1149, fig.1A
Trivial name: colominic acid, polysialic acid, α-2,8/2,9-linked polysialic acid
Compound class: CPS, K-antigen
Contained glycoepitopes: IEDB_136794,IEDB_146100,IEDB_149174,IEDB_150937,IEDB_153199,SB_170,SB_171,SB_172,SB_35,SB_42,SB_84
Methods: 1H NMR, PCR, SDS-PAGE, MALDI-TOF MS, genetic methods, biochemical methods, STD NMR, binding assays
Comments, role: published polymerization frame was shifted for conformity with other records.
3D data: 3D data, molecular modeling
Related record ID(s): 27248, 28454
NCBI Taxonomy refs (TaxIDs): 562Reference(s) to other database(s): GTC:G85948DP, GlycomeDB:
26537
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There is only one chemically distinct structure:
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