The mechanistic underpinnings of the complex process of plant polysaccharide biosynthesis are poorly understood, largely due to the lack of structural characterization in glycosyltransferase (GT) enzymes. In Arabidopsis thaliana, fucosyltransferase-1 (AtFUT1) catalyzes the regiospecific transfer of terminal 1,2-fucosyl residues to xyloglucan side chains - one of the finishing steps in arabinoxylan biosynthesis. In this talk, we discuss the development of the mechanistic basis for fucosylation by AtFUT1 using molecular simulations whose results are aided and corroborated by mutlipronged experiments. The structural architecture of AtFUT1 in complex with bound donor and acceptor substrate analogs lays the foundations for gaining insight into the fucosylation reaction mechanism. Detailed molecular dynamics simulations and quantum mechanical calculations lead us to propose an atypical water-mediated fucosylation mechanism facilitated by an H-bonded network, which is corroborated by mutagenesis experiments.

Xyloglucan fucosylation in Arabidopsis thaliana: A water mediated reaction mechanism

254th National Meeting (2017)

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