title: Cloning and analysis of the xylAB operon and characterization of xylose isomerase from Thermoanaerobacter ethanolicus.
abstract: Three genes, xylA-like, xylA and xylB, were cloned and sequenced from the chromosome of Thermoanaerobacter ethanolicus JW200. xylA and xylB share an operon and encode xylose isomerase and xylulokinase, respectively. The xylA-like gene locates upstream of xylAB operon and encodes a hypothetical protein that lacks xylose isomerase activity. The xylose isomerase was expressed in Escherichia coli and purified by heat treatment and an ion-exchange chromatography. The enzyme had highest activity at 85°C and pH 7.0, and a half-life for 1 h at 85°C. The K (m) and V (max) values for xylose were 11 mM and 25 U/mg, respectively. The high level of expression, easy purification, and thermostability of the XylA from T. ethanolicus JW200 suggests industrial usefulness.
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Bio-resources, College of Life Sciences, Nanjing Normal University, Nanjing, 210046, China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Fan
authors.forename: Yongchang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Qu
authors.forename: Jingkai
authors.initials: J
authors.lastname: Wang
authors.forename: Weilan
authors.initials: W
authors.lastname: Shao
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D046968:Thermoanaerobacter / Q000201:enzymology* / Q000235:genetics
chemical_list: D017853:Phosphotransferases (Alcohol Group Acceptor); C032700:xylulokinase; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase