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

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.