Improvement of the enzymatic activity of the hyperthermophilic cellulase from Pyrococcus horikoshii.
A hyperthermophilic beta-1,4 endoglucanase (EGPh) from the hyperthermophilic archaeon Pyrococcus horikoshii exhibits a strong hydrolyzing activity toward crystalline cellulose. The characteristic features of EGPh are: (1) it appears to have disulfide bonds, which is rare among anaerobic hyperthermophilic archaeon proteins, and (2) it lacks a carbohydrate-binding domain, which is necessary for effective hydrolysis of cellulose. We first examined the relationship between the disulfide bonds and the catalytic activity by analyzing various cysteine mutations. The activities of the mutated enzymes toward carboxy methyl cellulose (CMC) increased without any loss in thermostability. Second, we prepared a fusion enzyme so that the thermostable chitin-binding domain of chitinase from P. furiosus was joined to the C-terminus of EGPh and its variants. These fusion enzymes showed stronger activities than did the wild-type EGPh toward both CMC and crystalline cellulose (Avicel).
Kang
Hee-Jin
HJ
National Institute of Advanced Industrial Science and Technology, 1-18-31, Midorigaoka, Ikeda, Osaka, 563-8577, Japan.
Uegaki
Koichi
K
Fukada
Harumi
H
Ishikawa
Kazuhiko
K
D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D002384:Catalysis; D002480:Cellulase / Q000737:chemistry* / Q000235:genetics; D002482:Cellulose / Q000737:chemistry; D002688:Chitinases / Q000737:chemistry* / Q000235:genetics; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary / Q000235:genetics; D043902:Pyrococcus horikoshii / Q000201:enzymology* / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics
D019843:Archaeal Proteins; D011993:Recombinant Fusion Proteins; D002482:Cellulose; D002688:Chitinases; D002480:Cellulase