期刊
BIORESOURCE TECHNOLOGY
卷 107, 期 -, 页码 25-32出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.biortech.2011.12.106
关键词
Cellulosimicrobium sp strain HY-13; Eisenia fetida; Gut bacterium; Endo-beta-1,4-xylanase; Transglycosylation activity
资金
- 21C Frontier Microbial Genomics and Applications Center of the Ministry of Education, Science and Technology [MGC0901134]
- Ministry for Food, Agriculture, Forestry and Fisheries, Republic of Korea [AGM1171011, AGM0111112]
The gene (2304-bp) encoding a novel xylanolytic enzyme (XylK2) with a catalytic domain, which is 70% identical to that of Cellulomonas flavigena DSM 20109 GH6 beta-1,4-cellobiohydrolase, was identified from an earthworm (Eisenia fetida)-symbiotic bacterium, Cellulosimicrobium sp. strain HY-13. The enzyme consisted of an N-terminal catalytic GH6-like domain, a fibronectin type 3 (Fn3) domain, and a C-terminal carbohydrate-binding module 2 (CBM 2). XylK2 Delta Fn3-CBM 2 displayed high transferase activity (788.3 IU mg(-1)) toward p-nitrophenyl (PNP) cellobioside, but did not degrade xylobiose, glucose-based materials, or other PNP-sugar derivatives. Birchwood xylan was degraded by XylK2 Delta Fn3-CBM 2 to xylobiose (59.2%) and xylotriose (40.8%). The transglycosylation activity of the enzyme, which enabled the formation of xylobiose (33.6%) and xylotriose (66.4%) from the hydrolysis of xylotriose, indicates that it is not an inverting enzyme but a retaining enzyme. The endo-beta-1,4-xylanase activity of XylK2 Delta Fn3-CBM 2 increased significantly by approximately 2.0-fold in the presence of 50 mM xylobiose. (C) 2011 Elsevier Ltd. All rights reserved.
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