Identification of the cellulose-binding and the cell wall-binding domains of Eubacterium cellulosolvens 5 cellulose-binding protein A (CBPA).
The cellulose-binding domain (CBD) and the cell wall-binding domain (CWBD) of Eubacterium cellulosolvens 5 cellulose-binding protein A (CBPA) have been determined. The gene (cbpA) encoding CBPA and its derivatives were expressed in Escherichia coli. We were able to obtain the eight recombinant proteins and examine for their cellulose-binding ability, cell wall-binding ability and carboxymethyl cellulase (CMCase) activity. Since five recombinant proteins, which contain the unknown domain (UD-2) located between two linker-like regions of CBPA, bound to cellulose, this region has been identified as the CBD. The CBD did not show a significant sequence similarity with any other CBDs. Moreover, the N-terminal region of CBPA showed a significant sequence similarity with a catalytic domain of glycosyl hydrolase family 9, and the recombinant proteins containing the region showed CMCase activity. Since the UD-3, which is located in the C-terminal region of CBPA, bound to the cell walls of E. cellulosolvens 5, the region has been identified as the CWBD. However, the CWBD did not show a significant sequence similarity with any other proteins previously reported.
College of Agriculture, Ibaraki University, Ami, Japan. atoyoda@acs.ipc.ibaraki.ac.jp
Atsushi
A
Toyoda
Hajime
H
Minato
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D002480:Cellulase / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005051:Eubacterium / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D002352:Carrier Proteins; D011994:Recombinant Proteins; D002482:Cellulose; D002480:Cellulase