Binding characteristics of a bacterial expansin (BsEXLX1) for various types of pretreated lignocellulose.
BsEXLX1 from Bacillus subtilis is the first discovered bacterial expansin as a structural homolog of a plant expansin, and it exhibited synergism with cellulase on the cellulose hydrolysis in a previous study. In this study, binding characteristics of BsEXLX1 were investigated using pretreated and untreated Miscanthus x giganteus in comparison with those of CtCBD3, a cellulose-binding domain from Clostridium thermocellum. The amounts of BsEXLX1 bound to cellulose-rich substrates were significantly lower than those of CtCBD3. However, the amounts of BsEXLX1 bound to lignin-rich substrates were much higher than those of CtCBD3. A binding competition assay between BsEXLX1 and CtCBD3 revealed that binding of BsEXLX1 to alkali lignin was not affected by the presence of CtCBD3. This preferential binding of BsEXLX1 to lignin could be related to root colonization in plants by bacteria, and the bacterial expansin could be used as a lignin blocker in the enzymatic hydrolysis of lignocellulose.
School of Life Sciences and Biotechnology, Korea University, Seoul 136-713, South Korea.
In Jung
IJ
Kim
Hyeok-Jin
HJ
Ko
Tae-Wan
TW
Kim
Ki Hyun
KH
Nam
In-Geol
IG
Choi
Kyoung Heon
KH
Kim
D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D048013:Acetivibrio thermocellus / Q000378:metabolism; D008031:Lignin / Q000378:metabolism*; D008958:Models, Molecular; D006109:Poaceae / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation
D001426:Bacterial Proteins; D002352:Carrier Proteins; C036909:lignocellulose; D008031:Lignin