Download MendeleyStructural, mutagenic and in silico studies of xyloglucan fucosylation in Arabidopsis thaliana suggest a water-mediated mechanism.
Urbanowicz, B.R., Bharadwaj, V.S., Alahuhta, M., Pena, M.J., Lunin, V.V., Bomble, Y.J., Wang, S., Yang, J.Y., Tuomivaara, S.T., Himmel, M.E., Moremen, K.W., York, W.S., Crowley, M.F.(2017) Plant J 91: 931-949
- PubMed: 28670741
- DOI: https://doi.org/10.1111/tpj.13628
- Primary Citation of Related Structures:
5KWK, 5KX6 - PubMed Abstract:
The mechanistic underpinnings of the complex process of plant polysaccharide biosynthesis are poorly understood, largely because of the resistance of glycosyltransferase (GT) enzymes to structural characterization. In Arabidopsis thaliana, a glycosyl transferase family 37 (GT37) fucosyltransferase 1 (AtFUT1) catalyzes the regiospecific transfer of terminal 1,2-fucosyl residues to xyloglucan side chains - a key step in the biosynthesis of fucosylated sidechains of galactoxyloglucan. We unravel the mechanistic basis for fucosylation by AtFUT1 with a multipronged approach involving protein expression, X-ray crystallography, mutagenesis experiments and molecular simulations. Mammalian cell culture expressions enable the sufficient production of the enzyme for X-ray crystallography, which reveals the structural architecture of AtFUT1 in complex with bound donor and acceptor substrate analogs. The lack of an appropriately positioned active site residue as a catalytic base leads us to propose an atypical water-mediated fucosylation mechanism facilitated by an H-bonded network, which is corroborated by mutagenesis experiments as well as detailed atomistic simulations.
Organizational Affiliation:
Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA.
