6CCI
The Crystal Structure of XOAT1
Summary for 6CCI
| Entry DOI | 10.2210/pdb6cci/pdb |
| Descriptor | Protein ESKIMO 1, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, COBALT (II) ION, ... (6 entities in total) |
| Functional Keywords | acetyltransferase, arabidopsis thaliana, transferase |
| Biological source | Arabidopsis thaliana (Mouse-ear cress) |
| Total number of polymer chains | 1 |
| Total formula weight | 58447.56 |
| Authors | Alahuhta, P.M.,Lunin, V.V. (deposition date: 2018-02-07, release date: 2019-02-20, Last modification date: 2024-11-06) |
| Primary citation | Lunin, V.V.,Wang, H.T.,Bharadwaj, V.S.,Alahuhta, M.,Pena, M.J.,Yang, J.Y.,Archer-Hartmann, S.A.,Azadi, P.,Himmel, M.E.,Moremen, K.W.,York, W.S.,Bomble, Y.J.,Urbanowicz, B.R. Molecular Mechanism of Polysaccharide Acetylation by the Arabidopsis XylanO-acetyltransferase XOAT1. Plant Cell, 32:2367-2382, 2020 Cited by PubMed Abstract: Xylans are a major component of plant cell walls. -Acetyl moieties are the dominant backbone substituents of glucuronoxylan in dicots and play a major role in the polymer-polymer interactions that are crucial for wall architecture and normal plant development. Here, we describe the biochemical, structural, and mechanistic characterization of Arabidopsis () xylan -acetyltransferase 1 (XOAT1), a member of the plant-specific Trichome Birefringence Like (TBL) family. Detailed characterization of XOAT1-catalyzed reactions by real-time NMR confirms that it exclusively catalyzes the 2--acetylation of xylan, followed by nonenzymatic acetyl migration to the -3 position, resulting in products that are monoacetylated at both -2 and -3 positions. In addition, we report the crystal structure of the catalytic domain of XOAT1, which adopts a unique conformation that bears some similarities to the α/β/α topology of members of the GDSL-like lipase/acylhydrolase family. Finally, we use a combination of biochemical analyses, mutagenesis, and molecular simulations to show that XOAT1 catalyzes xylan acetylation through formation of an acyl-enzyme intermediate, Ac-Ser-216, by a double displacement bi-bi mechanism involving a Ser-His-Asp catalytic triad and unconventionally uses an Arg residue in the formation of an oxyanion hole. PubMed: 32354790DOI: 10.1105/tpc.20.00028 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.85 Å) |
Structure validation
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