[Improvement of the thermostability of xylanase by N-terminus replacement].
The hybrid xylanase TB was constructed by the substitution of the N-terminus segment of the Streptomyces olivaceoviridis xylanase XYNB with corresponding region of Thermomonosporafusca xylanase TfxA. The hybrid gene tb, encoding the TB, was correctly expressed in Escherichia coli BL21 and Pichia pastoris GS115. TB was purified and its enzymatic properties were determined. The results revealed that the optimal temperature and optimal pH of TB were at 70 degrees C and 6.0, which have been obviously improved compared with those of XYNB. The thermostability of TB were all about six-fold of XYNB's after incubating the properly diluted enzyme solutions at 80 degrees C and 90 degrees C for 3min, respectively. The pH stability of TB was 5 to approximately 9, which was narrower than that of XYNB. Still, TB remains a high specific activity as XYNB does. Analysis of a homology modeling and sequence similarity were used to reveal the factors influencing the enzymatic properties of TB and the discussion for the relationship between structure and function of xylanase was given.
Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Hao-Meng
HM
Yang
Kun
K
Meng
Hui-Ying
HY
Luo
Ya-Ru
YR
Wang
Tie-Zheng
TZ
Yuan
Ying-Guo
YG
Bai
Bin
B
Yao
Yun-Liu
YL
Fan
D000595:Amino Acid Sequence; D001483:Base Sequence; D019620:Desulfurococcaceae / Q000201:enzymology* / Q000235:genetics; D043364:Endo-1,4-beta Xylanases / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006358:Hot Temperature; D008969:Molecular Sequence Data; D010843:Pichia / Q000201:enzymology / Q000235:genetics; D015202:Protein Engineering / Q000379:methods*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics; D013329:Structure-Activity Relationship
D011993:Recombinant Fusion Proteins; D043364:Endo-1,4-beta Xylanases