Structural highlights
Publication Abstract from PubMedCellulases hydrolyze cellulose, a major component of plant cell walls, to oligosaccharides and monosaccharides. Several Clostridium species secrete multi-enzyme complexes (cellulosomes) containing cellulases. C. thermocellum CelT, a family 9 cellulase, lacks the accessory module(s) necessary for activity, unlike most other family 9 cellulases. Therefore, characterization of the CelT structure is essential in order to understand its catalytic mechanism. Here, the crystal structure of free CelTDeltadoc, the catalytic domain of CelT, is reported at 2.1 A resolution. Its structure differs in several aspects from those of other family 9 cellulases. CelTDeltadoc contains an additional alpha-helix, alpha-helices of increased length and two additional surface-exposed beta-strands. It also contains three calcium ions instead of one as found in C. cellulolyticum Cel9M. CelTDeltadoc also has two flexible loops at the open end of its active-site cleft. Movement of these loops probably allows the substrate to access the active site. CelT is stable over a wide range of pH and temperature conditions, suggesting that CelT could be used to convert cellulose biomass into biofuel. Structure of the catalytic domain of the Clostridium thermocellum cellulase CelT.,Kesavulu MM, Tsai JY, Lee HL, Liang PH, Hsiao CD Acta Crystallogr D Biol Crystallogr. 2012 Mar;68(Pt 3):310-20. Epub 2012 Feb 14. PMID:22349233[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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