title: Novel alkali-stable, cellulase-free xylanase from deep-sea Kocuria sp. Mn22.
abstract: A novel xylanase gene, Kxyn, was cloned from Kocuria sp. Mn22, a bacteria isolated from the deep sea of the east Pacific. Kxyn consists of 1,170 bp and encodes a protein of 390 amino acids that shows the highest identity (63%) with a xylanase from Thermobifida fusca YX. The mature protein with a molecular mass of approximately 40 kDa was expressed in Escherichia coli BL21 (DE3). The recombinant Kxyn displayed its maximum activity at 55 degrees and at pH 8.5. The Km, Vmax, and kcat values of Kxyn for birchwood xylan were 5.4 mg/ml, 272 micromol/min.mg, and 185.1/s, respectively. Kxyn hydrolyzed birchwood xylan to produce xylobiose and xylotriose as the predominant products. The activity of Kxyn was not affected by Ca2+, Mg2+, Na+, K+, beta- mercaptoethanol, DTT, or SDS, but was strongly inhibited by Hg2+, Cu2+, Zn2+, and Pb2+. It was stable over a wide pH range, retaining more than 80% activity after overnight incubation at pH 7.5-12. Kxyn is a cellulase-free xylanase. Therefore, these properties make it a candidate for various industrial applications.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University,Wuhan 430070, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Chanjuan
authors.forename: Yuzhi
authors.initials: Y
authors.lastname: Hong
authors.forename: Zongze
authors.initials: Z
authors.lastname: Shao
authors.forename: Ling
authors.initials: L
authors.lastname: Lin
authors.forename: Xiaoluo
authors.initials: X
authors.lastname: Huang
authors.forename: Pengfu
authors.initials: P
authors.lastname: Liu
authors.forename: Gaobing
authors.initials: G
authors.lastname: Wu
authors.forename: Xin
authors.initials: X
authors.lastname: Meng
authors.forename: Ziduo
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D002480:Cellulase / Q000235:genetics; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006094:Gram-Positive Bacteria / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012623:Seawater / Q000382:microbiology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D019710:Thermococcaceae
chemical_list: D011994:Recombinant Proteins; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases