A thermophilic and acid stable family-10 xylanase from the acidophilic fungus Bispora sp. MEY-1.
A complete gene, xyl10C, encoding a thermophilic endo-1,4-beta-xylanase (XYL10C), was cloned from the acidophilic fungus Bispora sp. MEY-1 and expressed in Pichia pastoris. XYL10C shares highest nucleotide and amino acid sequence identities of 57.3 and 49.7%, respectively, with a putative xylanase from Aspergillus fumigatus Af293 of glycoside hydrolase family 10. A high expression level in P. pastoris (73,400 U ml(-1)) was achieved in a 3.7-l fermenter. The purified recombinant XYL10C was thermophilic, exhibiting maximum activity at 85 degrees C, which is higher than that reported from any fungal xylanase. The enzyme was also highly thermostable, exhibiting approximately 100% of the initial activity after incubation at 80 degrees C for 60 min and >87% of activity at 90 degrees C for 10 min. The half lives of XYL10C at 80 and 85 degrees C were approximately 45 and 3 h, respectively. It had two activity peaks at pH 3.0 and 4.5-5.0 (maximum), respectively, and was very acid stable, retaining more than 80% activity after incubation at pH 1.5-6.0 for 1 h. The enzyme was resistant to Co(2+), Mn(2+), Cr(3+) and Ag(+). The specific activity of XYL10C for oat spelt xylan was 18,831 U mg(-1). It also had wide substrate specificity and produced simple products (65.1% xylose, 25.0% xylobiose and 9.9% xylan polymer) from oat spelt xylan.
Luo
Huiying
H
Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, 100081, Beijing, People's Republic of China.
Li
Jiang
J
Yang
Jun
J
Wang
Hui
H
Yang
Yuhui
Y
Huang
Huoqing
H
Shi
Pengjun
P
Yuan
Tiezheng
T
Fan
Yunliu
Y
Yao
Bin
B
D000595:Amino Acid Sequence; D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010843:Pichia / Q000201:enzymology / Q000235:genetics; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature
D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins; D011994:Recombinant Proteins; D043364:Endo-1,4-beta Xylanases