Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
Updates will be given on advanced biophysical imaging techniques we have developed and applied to characterization of plant cell wall structure and chemistry, as well as cellulase interaction with cellulose at the nanometer scale. Coherent Raman Scattering (CRS) microscopy is a label-free approach that is capable of tracking molecule at video rate (Saar et al., 2010, Science, 330, 1368). Using CRS, we have demonstrated the quantitative analysis of lignin and cellulose contents in both native and lignin-down-regulated plant cell walls, and proposed that lignin reduction in different areas of cell walls could account for enhanced susceptibility to chemical and enzymatic hydrolysis (Zeng et al., 2010, BioEnergy Res. 3, 272). CRS has also been used for the real-time monitoring of acid-chlorite delignification of the plant cell wall, and suggested that the hydrolysis of lignin in different areas of cell wall manifests different kinetics (Saar et al., 2010, Angew. Chem. Int. Ed. 49, 5476). Single-molecule approaches, such as Total Internal Reflection Fluorescence (TIRF) and Defocused Orientation and Position Imaging (DOPI) techniques, have been used to image in situ binding of carbohydrate-binding modules (CBMs) to cellulose; we have found that CBMs bind to specific surfaces of cellulose crystal with defined orientations (Dagel et al., 2010, J. Phys. Chem. B). Combining previous results with new Atomic Force Microscopy (AFM) data, we have further demonstrated that at least one cellulase (i.e., T. reesei Cel7A) hydrolyzes specific faces of the cellulose crystal (Liu et al., unpublished).