Complete Cellulase System in the Marine Bacterium Saccharophagus degradans Strain 2-40 ^T

Abstract

Saccharophagus degradans strain 2-40 is a representative of an emerging group of marine complex polysaccharide (CP)-degrading bacteria. It is unique in its metabolic versatility, being able to degrade at least 10 distinct CPs from diverse algal, plant and invertebrate sources. The S. degradans genome has been sequenced to completion, and more than 180 open reading frames have been identified that encode carbohydrases. Over half of these are likely to act on plant cell wall polymers. In fact, there appears to be a full array of enzymes that degrade and metabolize plant cell walls. Genomic and proteomic analyses reveal 13 cellulose depolymerases complemented by seven accessory enzymes, including two cellodextrinases, three cellobiases, a cellodextrin phosphorylase, and a cellobiose phosphorylase. Most of these enzymes exhibit modular architecture, and some contain novel combinations of catalytic and/or substrate binding modules. This is exemplified by endoglucanase Cel5A, which has three internal family 6 carbohydrate binding modules (CBM6) and two catalytic modules from family five of glycosyl hydrolases (GH5) and by Cel6A, a nonreducing-end cellobiohydrolase from family GH6 with tandem CBM2s. This is the first report of a complete and functional cellulase system in a marine bacterium with a sequenced genome.

Label-Free Protein Quantification for Plant Golgi Protein Localization and Abundance

“…Each of these proteins was found with similar abundances within the experimental error of this technique (ranks 65, 75, and 73, respectively), which is consistent with the theory that the CesA proteins form a stoichiometric complex (Taylor et al, 2006). Three distinct CesA isoforms form the primary wall cellulose synthesis complex.…”

Global metabolic profiling of plant cell wall polysaccharide degradation by Saccharophagus degradans

“…The minimal media were supplemented with 0.2% (w/v) glucose, xylose, Avicel (Sigma-Aldrich, St. Louis, MO) or xylan from beechwood (Sigma-Aldrich) when needed (Taylor et al, 2006).…”

“…The crude enzyme preparation of 18 mL, which was the supernatant obtained after washing and subsequent milling of cells, was added to 36 mL of 0.05 M sodium phosphate buffer (pH 7.0) containing a substrate at 1% (w/v) (Ensor et al, 1999;Taylor et al, 2006). To assay cellulase, an enzyme reaction mixture containing Avicel was incubated at 308C for 6 h, and the xylanase activity was measured by incubating the enzyme reaction mixture containing xylan from beechwood at 308C for 20 min.…”

“…Saccharophagus degradans 2-40, which was isolated from marine salt marsh grass, was found to be capable of degrading algae and higher plant materials, and its full genome was recently sequenced by US Department of Energy's Joint Genome Institute (Andrykovitch and Marx, 1988;Weiner et al, 2008). The sequencing revealed the presence of more than 180 open reading frames that encode carbohydrases (Ekborg et al, 2005;Taylor et al, 2006). Furthermore, genomic and proteomic analyses of the complete cellulase system, including xylanase, resulted in the development of a cellulose degradation model composed of well-conserved cellulases (Taylor et al, 2006).…”

“…The sequencing revealed the presence of more than 180 open reading frames that encode carbohydrases (Ekborg et al, 2005;Taylor et al, 2006). Furthermore, genomic and proteomic analyses of the complete cellulase system, including xylanase, resulted in the development of a cellulose degradation model composed of well-conserved cellulases (Taylor et al, 2006). Due to the versatility and the high capability of S. degradans to degrade polysaccharides, the application of the strain has received much attention, and it has even been evaluated for commercialization (http://www.zymetis.com).…”