|Li, Xin Liang|
Submitted to: Gordon Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/3/2007
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: Several types of covalent linkages between lignin and xylan in plant cell walls have been shown. One of such linkages could be an ester bond between hydroxyl groups of lignin moieties and the carboxyl group of the 4-O-methyl-D-glucuronic acid (MeGlcA) side groups of glucuronoxylan. Enzymes capable of specifically hydrolyzing the methyl ester of MeGlcA have been purified from cellulolytic fungi and named glucuronoyl esterases (GE) (S. Spanikova and P. Biely, FEBS Lett. 580, 4597-4601, 2006). We have recently identified fungal genes coding for the GEs. Sequence analysis revealed homology between the fungal GEs and the C terminal functionally unknown domain of a cellulosomal acetyl esterase (CesA) of Ruminococcus flavefaciens 17 (V. Aurilia et al., Microbiology, 146, 1391-1397, 2000). The domain has been over-expressed in Escherichia coli and purified to electrophoretical homogeneity by liquid chromatography. As postulated, the protein hydrolyzed the methyl ester of the MeGlcA, thus providing evidence for the first such enzyme in bacterial cellulosomes. In addition, the purified protein was crystallized by the hanging drop vapor diffusion method. The crystals diffracted X-rays to 2.4 A on the R-Axis IIc using rotating anode X-ray generator.