Biochemical and structural properties of a low-temperature-active glycoside hydrolase family 43 β-xylosidase: Activity and instability at high neutral salt concentrations. (15th December 2019)

• Record Type: Journal Article
• Authors: Zhang, Rui; Li, Na; Liu, Yu; Han, Xiaowei; Tu, Tao; Shen, Jidong; Xu, Shujing; Wu, Qian; Zhou, Junpei; Huang, Zunxi
• Is Part Of: Food chemistry. Volume 301(2019)
• Publication Date: 2019-12-15
• Subjects: 3D 3 Dimensions -- A adenosine -- bp base pair -- C cytosine -- Cα alpha carbon -- DNS 3, 5-dinitrosalicylic acid -- E. coli Escherichia coli -- Ea activation energy -- EC Enzyme Commission -- EDTA ethylenediaminetetraacetic acid -- Fig. figure -- G guanine -- GH glycoside hydrolase -- G. stearothermophilus Geobacillus stearothermophilus -- hj14GH43 the β-xylosidase-coding gene from Bacillus sp. HJ14 -- HJ14GH43 the β-xylosidase from Bacillus sp. HJ14 -- J joule -- K kelvin -- K2, D14, S29, F31, W73, A74, H102, F126, D127, R148, W145, H152, E186, T206, H248, R287, F504, A315, P316, T329, V330, E369, E426, I498, A507, E535 amino acid residues and their positions in HJ14GH43 -- kcat catalytic constant -- kDa kilodaltons -- kJ kilojoule -- Km Michaelis constant -- M moles per liter -- MALDI–TOF matrix-assisted laser desorption/ionization time-of-flight -- McIlvaine buffer a mixture of 0.1 mol/L citric acid and 0.2 mol/L Na2HPO4 -- mg milligram -- min minute -- mL milliliter -- mM millimoles per liter -- MS mass spectrometry -- n or no. number -- nm nanometer -- NR not reported -- NTA nitrilotriacetic acid -- N-terminal amino-terminal -- PAGE polyacrylamide gel electrophoresis -- PDB ID Protein Data Bank identity -- PEG polyethylene glycol -- pH potential of hydrogen -- pNP p-nitrophenol -- pNPXyl p-nitrophenyl-β-d-xylopyranoside -- Q10 temperature coefficient -- R refinement -- RCSB Research Collaboration for Structural Bioinformatics -- rHJ14GH43 the recombinant β-xylosidase from Bacillus sp. HJ14 -- RMS root mean square -- s second -- SD standard deviation -- SDS sodium dodecyl sulphate -- sp. species -- T thymine -- TLC thin layer chromatography -- Tris tris(hydroxymethyl)aminomethane -- U unit -- µL microliter -- µmol micromole -- v/v volume per volume -- Vmax maximum velocity -- w/v weight per volume -- ΔG* free energy of activation -- ΔH* enthalpy of activation -- ΔS* entropy of activation; β-Xylosidase -- Activity -- Stability -- Low temperature -- Salt -- Crystal structure -- Glycoside hydrolase; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2019.125266
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: A low-temperature-active glycoside hydrolase family 43 β-xylosidase was revealed. The enzyme showed considerable activity and instability in high neutral salts. Crystal structure comparison showed the enzyme had fewer salt bridges and H-bonds. Structure of the enzyme was highly flexible with large positively charged surface. Structural features led to low-temperature and high-salt adaptations of the enzyme. Abstract: β-Xylosidase, of the glycoside hydrolase family 43 from Bacillus sp. HJ14, was expressed in Escherichia coli . Recombinant β-xylosidase (rHJ14GH43) exhibited maximum activity at 25 °C, approximately 15, 45, and 88% of maximum activity at 0, 10, and 20 °C, respectively, and poor stability at temperatures over 20 °C. rHJ14GH43 showed moderate or high activity, but poor stability, in NaCl, KCl, NaNO3, KNO3, Na2 SO4, and (NH4 )2 SO4 at concentrations from 3.0 to 30.0% (w/v). The crystal structure of rHJ14GH43 was resolved and showed higher structural flexibility due to fewer salt bridges and hydrogen bonds compared to mesophilic and thermophilic β-xylosidases. High structural flexibility is presumed to be a key factor for catalytic adaptations to low temperatures and high salt concentrations. Approximately one-third of the surface of rHJ14GH43 is positively charged, which may be the primary factor responsible for poor stability in high neutral salt environments.