title: Gene cloning, expression and characterization of a new cold-active and salt-tolerant endo-beta-1,4-xylanase from marine Glaciecola mesophila KMM 241.
abstract: Although a lot of xylanases are studied, only a few xylanases from marine microorganisms have been reported. A new xylanase gene, xynA, was cloned from marine bacterium Glaciecola mesophila KMM 241. Gene xynA contains 1,272 bp and encodes a 423-amino acid xylanase precursor. The recombinant xylanase, XynA, expressed in Escherichia coli BL21 is a monomer with a molecular mass of 43 kDa. Among the characterized xylanases, XynA shares the highest identity (46%) to the xylanase from Flavobacterium sp. strain MSY2. The optimum pH and temperature for XynA is 7.0 and 30 degrees C. XynA retains 23% activity and 27% catalytic efficiency at 4 degrees C. XynA has low thermostability, remaining 20% activity after 60-min incubation at 30 degrees C. Its apparent melting temperature (T (m)) is 44.5 degrees C. These results indicate that XynA is a cold-active xylanase. XynA shows a high level of salt-tolerance, with the highest activity at 0.5 M NaCl and retaining 90% activity in 2.5 M NaCl. It may be the first salt-tolerant xylanase reported. XynA is a strict endo-beta-1,4-xylanase with a demand of at least four sugar moieties for effective cleavage. It efficiently hydrolyzes xylo-oligosaccharides and xylan into xylobiose and xylotriose without producing xylose, suggesting its potential in xylo-oligosaccharides production.
authors.affiliation: Marine Biotechnology Research Center, Shandong University, Jinan, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Guo
authors.forename: Xiu-Lan
authors.initials: XL
authors.lastname: Chen
authors.forename: Cai-Yun
authors.initials: CY
authors.lastname: Sun
authors.forename: Bai-Cheng
authors.initials: BC
authors.lastname: Zhou
authors.forename: Yu-Zhong
authors.initials: YZ
authors.lastname: Zhang
mesh_terms: D034241:Alteromonadaceae / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000378:metabolism; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis; D055049:Salt Tolerance; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014871:Water Microbiology; D043325:Xylan Endo-1,3-beta-Xylosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D011994:Recombinant Proteins; D043325:Xylan Endo-1,3-beta-Xylosidase