Understanding the mechanism of (1,3; 1,4)-β-D-glucan synthesis in cereals

MS Doblin1, D Oehme1,2, YY Ho3, MP Bain1, K Ford1, ER Lampugnani1 and A Bacic1

  1. Australian Research Council Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010 Australia
  2. IBM Research-Australia, Carlton, VIC 3053, Australia
  3. Adelaide Proteomics Centre, School of Biological Sciences, The University of Adelaide, North Terrace Campus, SA 5005 Australia

Mixed linkage (1,3;1,4)-β-glucan (MLG) is a major non-cellulosic polysaccharide of the commelinid monocot cell walls and an important soluble dietary fibre component found in abundance in cereals. Yet despite its importance, relatively little is known about the molecular mechanism involved in the synthesis and assembly of this polysaccharide. Using functional genomics, the commelinid-specific Cellulose Synthase-Like (CSL) F, CSLH and CSLJ multi-gene families within the larger CAZy GT2 family have been identified as encoding the catalytic components of the MLG synthase enzyme (1-3). We have adopted a multi-disciplinary approach, including molecular, biochemical, proteomic and computational techniques to study CSLF6, the major MLG synthase in grasses. We have built homology models of various GT2 enzymes based upon the recently crystallised bacterial cellulose synthase BcsA (5-6) and have used molecular dynamics (MD) simulations to shed light on what protein features play a role in determining the specificity and sequence of the glycosidic linkages within this polysaccharide synthase family. We will present computational findings as well as experimental data relating protein structure to function. In addition, we will reveal biochemical evidence as to the modes of regulation of CSLF6.
References: 1. Burton et al. (2006) Science 311, 1940-1942; 2. Doblin et al. (2009) PNAS USA 106, 5996-6001; 3. Little et al. (2016), submitted; 4. Smith & Stone (1973) Phytochem 12, 1361-1367; 5. Morgan et al. (2013) Nature 493, 181-186; 6. Morgan et al. (2014) Nature Struc & Mol Biol 21, 489-496.