Identification of the cellulose-binding domain of the cellulosome subunit S1 from Clostridium thermocellum YS


H.J. Gilbert, Department of Biological and Nutritional Sciences, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK.


Abstract The 3′ region of a gene designated cipB, which shows strong homology with cipA that encodes the cellulosome SL subunit of Clostridium thermocellum ATCC 27405, was isolated from a gene library of C. thermocellum strain YS. The truncated S1 protein encoded by the cipB derivative bound tightly to cellulose. The cellulose-binding domain in this polypeptide consisted of a C-terminal proximal 167 residue sequence which showed complete identity with residues 337–503 of mature SL from C. thermocellum strain ATCC 27405. The cellulose-binding domain interacted with both crystalline and amorphous cellulose, but not with xylan.