Xanthomonas campestris expansin-like X domain is a structurally disordered beta-sheet macromolecule capable of synergistically enhancing enzymatic efficiency of cellulose hydrolysis

• Published in: Biotechnology letters 2015-12, Vol.37 (12), p.2419-2426
• Main Authors: Junior, Atílio Tomazini, Dolce, Luciano Graciani, de Oliveira Neto, Mario, Polikarpov, Igor
• Format: Article
• Language: English
• Subjects: Applied Microbiology; Bacillus; Biochemistry; Biomedical and Life Sciences; Biotechnology; Cellulose; Cellulose - metabolism; Chromatography, Liquid; Circular Dichroism; Culture; Cytosol - chemistry; Dichroism; Enzymes; Hydrogen-Ion Concentration; Hydrolases - chemistry; Hydrolases - isolation & purification; Hydrolases - metabolism; Hydrology; Hydrolysis; Ion exchangers; Life Sciences; Macromolecules; Microbiology; Molecules; Original Research Paper; Protein Conformation; Proteins; Rendering; Scattering, Small Angle; Synergistic effect; Xanthomonas campestris; Xanthomonas campestris - enzymology
• ISSN: 0141-5492; 1573-6776
• DOI: 10.1007/s10529-015-1927-9

Objectives To biochemically characterize an expansin-like X protein domain from Xanthomonas campestris (XcEXLX1) and to study its synergy with cellulases in cellulose depolymerization. Results The protein was purified using a combination of ion exchange and size exclusion chromatography rendering about 30 mg pure protein/l culture medium. Circular dichroism spectroscopy and small-angle X-ray scattering studies of XcEXLX1 reveal that it is a strongly disordered β-sheet protein. Its low resolution envelope fits nicely the crystallographic structure of the homologous protein EXLX1 from Bacillus subtillis . Furthermore, we demonstrate that XcEXLX1 shows a synergistic, pH-dependent effect when combined with a commercial enzymatic preparation (Accellerase 1500), enhancing its hydrolytic activity on a cellulosic substrate. The strongest effect was observed in acid pHs with an increase in sugar release of up to 36 %. Conclusion The synergistic effect arising from the action of the expansin-like protein was considerable in the presence of significantly larger amounts of the commercial enzymatic cocktail then previously observed (0.35 FPU of Accellerase 1500/g substrate).