Structural and functional features of the linker region from the modular cellulase of B. subtilis.

D RUIZ; V TUROWSKI; M MURAKAMI

Dresden

Congreso; 10th European Biophysics Congress (EBSA 2015); 2015

European Biophysical Societies' Association (EBSA)

The plant cell wall has a complex structure composed by microfibrils of cellulose embedded in a hemicellulosic matrix, requiring a broad repertoire of glycoside hydrolases for its complete reduction to simple sugars. In the nature, there are numerous carbohydrate-active enzymes with modular structure consisting of at least one catalytic core and one or more accessory domains. The presence of accessory domains in these enzymes has been associated with higher catalytic efficiency, extension of the catalytic core or targeting of the enzyme to the proper substrate, to name a few. However, the importance of the linker region for the synergistic action between catalytic and accessory domains remains elusive. Thus, in this way, we have been performed an extensive mutational, biophysical and biochemical characterization of the cellulase from Bacillus subtilis (BsCel5A) which is composed of a catalytic domain (GH5) and a cellulose binding domain (CBM3) connected by a 23-residue-long linker. The study of several variants of BsCel5A, in terms of length and flexibility of the linker region, revealed a clear correlation between inter-domain mobility and catalytic efficiency, which is an important contribution for the rational design of modular enzymes.