title: Identification of a novel cellulose-binding domain within the endo-β-1,4-xylanase KRICT PX-3 from Paenibacillus terrae HPL-003.
abstract: The model 3-D structure of xylanase KRICT PX3 (JF320814) identified by DNA sequence analysis revealed a catalytic domain and CBM4-9 which functions as a xylan binding domain (XBD). To identify its role in xylan hydrolysis, six expression plasmids were constructed encoding the N-terminal CBM plus the catalytic domain or different glycosyl hydrolases, and the biochemical properties of the recombinant enzymes were compared to the original structure of PX3 xylanase. All six of the recombinant xylanases with the addition of CBM in the pIVEX-GST expression vector showed no improved PX3 hydrolytic activity. However, the absence of the CBM domain resulted in a decrement of 40% in thermostability, movement of the optimal temperature from 55°C to 45°C, alteration of the optimal pH range from 5-10 to 6-8, and reduction of the enzymatic activity to one-second under the same condition, respectively. The putative XBD in PX3 comprises a new N-terminal domain homologous to the catalytic thermostabilizing domains from other xylanases. Analysis of the main products released from xylan indicate that the recombinant enzymes act as endo-1,4-β-xylanases but differ in their hydrolysis of xylan from beech wood, birch wood, and oat spelt.
authors.affiliation: Nano-catalyst Research Group, Green Chemistry Division, Korea Research Institute of Chemical Technology, Yusoeong P.O. Box 107, Daejon, 305-600, Republic of Korea.
authors.forename: Dal Rye
authors.initials: DR
authors.lastname: Kim
authors.affiliation: Nano-catalyst Research Group, Green Chemistry Division, Korea Research Institute of Chemical Technology, Yusoeong P.O. Box 107, Daejon, 305-600, Republic of Korea.
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Lim
authors.affiliation: Nano-catalyst Research Group, Green Chemistry Division, Korea Research Institute of Chemical Technology, Yusoeong P.O. Box 107, Daejon, 305-600, Republic of Korea; Department of Green Chemistry and Environmental Biotechnology, University of Science & Technology, 217 Gajungro, Yuseong-gu, Daejon, 305-350, Republic of Korea.
authors.forename: Kee In
authors.initials: KI
authors.lastname: Lee
authors.affiliation: Nano-catalyst Research Group, Green Chemistry Division, Korea Research Institute of Chemical Technology, Yusoeong P.O. Box 107, Daejon, 305-600, Republic of Korea; Department of Green Chemistry and Environmental Biotechnology, University of Science & Technology, 217 Gajungro, Yuseong-gu, Daejon, 305-350, Republic of Korea. Electronic address: ithwang@krict.re.kr.
authors.forename: In Taek
authors.initials: IT
authors.lastname: Hwang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D002482:Cellulose / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D056507:Paenibacillus / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D014990:Xylans / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D014990:Xylans; D002482:Cellulose; D043364:Endo-1,4-beta Xylanases
keywords: Carbohydrate binding module; Hydrolysis; Thermostability; Xylanase