STRUCTURAL STUDIES OF A CELLULOSE-BINDING PROTEIN BY MAGIC-ANGLE SPINNING SOLID-STATE NMR

Anaerobic microorganisms have evolved a large extracellular enzyme complex called cellulosome, which enables the degradation of plants cell wall. Carbohydrate-binding module (CBM) is a large family of proteins that serve as scaffoldin-borne of the cellulosome multi-enzyme and its main role is to recognize and bind specifically to carbohydrates and in that manner concentrate the enzymes onto the substrate for efficient hydrolysis of polysaccharides in general and cellulose in particular. CBM plays an important role in locating the crystalline face of cellulose and therefore being one of the rate-limiting factors in the degradation process, in which simple sugars suitable for fermentation to biofuels are released.

Magic-angle spinning (MAS) solid-state NMR (ssNMR) have the ability to provide structural information of insoluble moieties in the atomic-resolution scale, therefore constitutes a potential tool for studding CBM proteins in their bound form. Our study concentrates on the 166 amino-acids protein CBM3b-CbhA by means of solid-state NMR (ssNMR). The data acquired using various multidimensional MAS NMR experiments enabled the secondary structure prediction, which results in good agreement with the recent X-ray structure[1]. The data will be used for the 3D structure determination of the protein in the free and cellulose-bound forms.