Structures of NodZ α1,6-fucosyltransferase in complex with GDP and GDP-fucose
- Argonne National Laboratory, Argonne, IL 60439 (United States)
- Polish Academy of Sciences, 61-704 Poznan (Poland)
Crystal structures of the bacterial α1,6-fucosyltransferase NodZ in complex with GDP and GDP-fucose are presented. Rhizobial NodZ α1,6-fucosyltransferase (α1,6-FucT) catalyzes the transfer of the fucose (Fuc) moiety from guanosine 5′-diphosphate-β-l-fucose to the reducing end of the chitin oligosaccharide core during Nod-factor (NF) biosynthesis. NF is a key signalling molecule required for successful symbiosis with a legume host for atmospheric nitrogen fixation. To date, only two α1,6-FucT structures have been determined, both without any donor or acceptor molecule that could highlight the structural background of the catalytic mechanism. Here, the first crystal structures of α1,6-FucT in complex with its substrate GDP-Fuc and with GDP, which is a byproduct of the enzymatic reaction, are presented. The crystal of the complex with GDP-Fuc was obtained through soaking of native NodZ crystals with the ligand and its structure has been determined at 2.35 Å resolution. The fucose residue is exposed to solvent and is disordered. The enzyme–product complex crystal was obtained by cocrystallization with GDP and an acceptor molecule, penta-N-acetyl-l-glucosamine (penta-NAG). The structure has been determined at 1.98 Å resolution, showing that only the GDP molecule is present in the complex. In both structures the ligands are located in a cleft formed between the two domains of NodZ and extend towards the C-terminal domain, but their conformations differ significantly. The structures revealed that residues in three regions of the C-terminal domain, which are conserved among α1,2-, α1,6- and protein O-fucosyltransferases, are involved in interactions with the sugar-donor molecule. There is also an interaction with the side chain of Tyr45 in the N-terminal domain, which is very unusual for a GT-B-type glycosyltransferase. Only minor conformational changes of the protein backbone are observed upon ligand binding. The only exception is a movement of the loop located between strand βC2 and helix αC3. In addition, there is a shift of the αC3 helix itself upon GDP-Fuc binding.
- OSTI ID:
- 22351253
- Journal Information:
- Acta Crystallographica. Section D: Biological Crystallography, Vol. 68, Issue Pt 2; Other Information: PMCID: PMC3266854; PMID: 22281745; PUBLISHER-ID: mn5007; OAI: oai:pubmedcentral.nih.gov:3266854; Copyright (c) International Union of Crystallography 2012; Country of input: International Atomic Energy Agency (IAEA); ISSN 0907-4449
- Country of Publication:
- Denmark
- Language:
- English
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