title: A novel xylanase with tolerance to ethanol, salt, protease, SDS, heat, and alkali from actinomycete Lechevalieria sp. HJ3.
abstract: A xylanase-coding gene (xynAHJ3, 1,104 bp) was cloned from Lechevalieria sp. HJ3 harbored in a saline soil sampled from Heijing town, aka the "town of salt", on the famous "Silk Route of the South". The gene encodes a 367-residue polypeptide (XynAHJ3) with the highest identity of 74.0 % with the endoxylanase from Streptomyces thermocarboxydus HY-15. The coding sequence of the mature protein (without the predicted signal peptide from M1 to S22) of xynAHJ3 was expressed in Escherichia coli BL21 (DE3). The activity of the purified recombinant XynAHJ3 (rXynAHJ3) was apparently optimal at 70 °C and pH 6.0, retained greater than 55 % xylanase activity at a concentration of 0.2-2.0 M Na(+) and 26 % at 4.0 M Na(+) (pH 7.5 20 °C), and showed 110.2 and 44.2 % xylanase activities in the presence of 100 mM SDS (pH 6.0 37 °C) and 10 % ethanol (pH 5.0 37 °C), respectively. rXynAHJ3 activity was stable at 50 °C and pH 4.0-11.0 for more than 60 min, in trypsin or proteinase K at 20 °C for 24 h (pH 7.5), in 10 % ethanol (v/v) (pH 5.0) at 30 or 37 °C for 72 h, in 80 % ethanol (v/v) for 1 h, and in 0.6 or 3 M NaCl (20 °C, pH 7.5) for 72 h. Compared with the majority of xylanases with tolerance to ethanol, salt, SDS, or protease (K (m) values of 1.42-15.1 mg ml(-1)), rXynAHJ3 showed a low K (m) value (0.8 mg ml(-1)) and showed only limited amino acid sequence identity with those other xylanases (less than 47 %).
authors.affiliation: Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.
authors.forename: Junpei
authors.initials: J
authors.lastname: Zhou
authors.forename: Yajie
authors.initials: Y
authors.lastname: Gao
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Dong
authors.forename: Xianghua
authors.initials: X
authors.lastname: Tang
authors.forename: Junjun
authors.initials: J
authors.lastname: Li
authors.forename: Bo
authors.initials: B
authors.lastname: Xu
authors.forename: Yuelin
authors.initials: Y
authors.lastname: Mu
authors.forename: Qian
authors.initials: Q
authors.lastname: Wu
authors.forename: Zunxi
authors.initials: Z
authors.lastname: Huang
mesh_terms: D000192:Actinomycetales / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D007218:Industrial Microbiology; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012965:Sodium Chloride / Q000378:metabolism; D012988:Soil Microbiology; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism
chemical_list: D012965:Sodium Chloride; D043364:Endo-1,4-beta Xylanases