The multidomain xylanase Xyn10B as a cellulose-binding protein in Clostridium stercorarium

The cells of Clostridium stercorarium F-9 grown on cellobiose bound to inso luble cellulose allomorphs such as phosphoric acid-swollen cellulose (ASC), Treatment of the cells with 3 M guanidine hydrochloride extracted surface- layer proteins from the cells and abolished the affinity of the cells for A SC. SDS-polyacrylamide gel electrophoresis, zymogram, and immunological ana lyses indicated that one of the major surface layer proteins was Xyn10B, wh ich is a modular xylanase comprising two family 22 carbohydrate-binding mod ules (CBMs), a family 10 catalytic domain of glycosyl hydrolases, a family 9 CBM, and two S-layer homologous (SLH) domains. The C. stercorarium F-9 ce lls treated with guanidine hydrochloride coprecipitated with ASC upon the a ddition of a derivative of Xyn10B containing both a CBM and SLH domain in a ddition to a catalytic domain, but not a derivative without Xyn10B-SLH doma ins, suggesting that Xyn10B functioned as a cellulose-binding protein in C. stercorarium F-9. (C) 2001 Federation of European Microbiological Societie s. Published by Elsevier Science B.V. All rights reserved.