Construction, expression, and characterization of a thermostable xylanase.
A hybrid gene, btx, encoding a thermostable xylanase, Btx, was constructed by substituting the 31 N-terminal amino acid residues of the Thermomonospora fusca xylanase A (TfxA) for the corresponding region of 22 amino acid residues of the Bacillus subtilis xylanase A (BsxA). The btx gene was expressed in Escherichia coli BL21. The halo size produced by xylanase Btx on a Remanzol brilliant blue R (RBB) xylan plate at 60 degrees C and pH 6.0 was larger than those of BsxA and TfxA. The molecular weight of Btx was 22 kDa. Temperature and pH optima for Btx were at 50-60 degrees C and 6.0, respectively. Btx showed activity over 80% over a pH range of 5.0-9.0, which was wider than that of BsxA, and was also more acid-resistant than TfxA. Btx exhibited significant thermostability compared with BsxA. The results show the importance of the N-terminal sequence of TfxA in thermostability.
Weng
Xiao-Yan
XY
Department of Biological Science, College of Life Science, Zhejiang University, Hangzhou, 310029, PR China.
Sun
Jian-Yi
JY
D000192:Actinomycetales / Q000201:enzymology / Q000235:genetics; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D015870:Gene Expression; D005798:Genes, Bacterial; D006824:Hybridization, Genetic; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D013696:Temperature; D014990:Xylans / Q000378:metabolism
D011994:Recombinant Proteins; D014990:Xylans; D043364:Endo-1,4-beta Xylanases