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PDBsum entry 5gyc
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References listed in PDB file
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Key reference
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Title
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Structure-Based protein engineering for thermostable and alkaliphilic enhancement of endo-β-1,4-Xylanase for applications in pulp bleaching.
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Authors
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K.Boonyapakron,
A.Jaruwat,
B.Liwnaree,
T.Nimchua,
V.Champreda,
P.Chitnumsub.
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Ref.
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J Biotechnol, 2017,
259,
95.
[DOI no: ]
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PubMed id
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Abstract
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In the pulp bleaching industry, enzymes with robust activity at high pH and
temperatures are desirable for facilitating the pre-bleaching process with
simplified processing and minimal use of chlorinated compounds. To engineer an
enzyme for this purpose, we determined the crystal structure of the Xyn12.2
xylanase, a xylan-hydrolyzing enzyme derived from the termite gut symbiont
metagenome, as the basis for structure-based protein engineering to improve
Xyn12.2 stability in high heat and alkaline conditions. Engineered cysteine
pairs that generated exterior disulfide bonds increased the kcatof
Xyn12.2 variants and melting temperature at all tested conditions. These
improvements led to up to 4.2-fold increases in catalytic efficiency at pH 9.0,
50°C for 1h and up to 3-fold increases at 60°C. The most effective variants,
XynTT and XynTTTE, exhibited 2-3-fold increases in bagasse hydrolysis at pH 9.0
and 60°C compared to the wild-type enzyme. Overall, engineering arginines and
phenylalanines for increased pKaand hydrogen bonding improved enzyme
catalytic efficiency at high stringency conditions. These modifications were the
keys to enhancing thermostability and alkaliphilicity in our enzyme variants,
with XynTT and XynTTTE being especially promising for their application to the
pulp and paper industry.
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