With more than 200 billion tons per year in the natural environment, cellulose is the most abundant biopolymer on Earth. Cellulose microfibrils, the fundamental scaffolding of the plant cell wall, are para-crystalline array of several dozen (1,4)-beta-D-glucan chains synthesized at the plasma membrane surface by large multicomponent complexes of cellulose synthase (CesA) proteins. We discovered that recombinant catalytic domains of CesA are two-domain structures that dimerize using Small-Angle X-ray Scattering (SAXS) experiments to derive 3-D surface contour structures (Olek et al. 2014). The catalytic domains of plant CesAs contain two unique sequences not found in prokaryotic ancestors – a Plant-Conserved Region (P-CR) and Class-Specific Region (CSR) of unknown function. Molecular docking experiments with the catalytic core predicted that the CSRs of CesAs are the dimerization domains. His group crystallized a recombinant Plant-Conserved Region (P-CR) and showed that it is primarily a coiled-coil domain positioned near the entrance to the active site of the catalytic core (Rushton et al. 2017). We have begun studies to define the assembly of CesAs into complexes at the Golgi membrane as part of a broader effort to characterize the dynamics of the Golgi proteome.
His group has annotated almost 1500 genes that function in wall biogenesis in Arabidopsis and rice, and were the first to establish and characterize the wall biogenesis genes of a model C4 grass, maize. His work today continues expand annotations of the many gene families of cell-wall related genes for grasses and other angiosperms (see http://cellwall.genomics.purdue.edu). A large repertory of biochemical and spectroscopic protocols to define the specific functions of a large number of genes of cell-wall biogenesis has been developed. They also explore the large diversity of maize by genome-wide association studies to identify candidate genes that contribute to traits that enhance biomass deconstruction and catalytic conversion to advanced biofuels and bio-based products.