Expression and characterization of a novel xylose-tolerant β-xylosidase from Leifsonia sp.ZF2019

Abstract:

[Objective] We cloned and expressed a novel β-xylosidase Xyl4900 from Leifsonia sp.ZF2019 isolated from Artipe eryx larvae and then investigated its enzymatic properties,aiming to provide foundations for developing β-xylosidase suitable for industrial application.[Methods] We used bioinformatics tools to analyze the gene of Xyl4900,expressed it in Escherichia coli,and investigated the enzymatic properties of the expressed protein.[Results] Xyl4900 had high homology with the β-glucosidase of GH3 family while had a domain of β-xylosidase.It was a novel β-xylosidase that could specifically hydrolyze 4-nitrophenyl β-D-xylopyranoside.Xyl4900 had the highest activity at 45℃ and pH 7.0,and it still maintained more than 80% of activity after being incubated at pH 6.0-9.0 for 14 h.This enzyme was barely affected by other metal ions (2.5 mmol/L) except Cu²⁺ and had strong tolerance to low-concentration organic solvents (5%,V/V).In addition,the Xyl4900 in 20%(W/V) NaCl or 100 mmol/L xylose solution showed the activity higher than 50%,demonstrating good salt or xylose tolerance.The K_m,V_max,and xylose inhibition constant K_i of Xyl4900 were 0.80 mmol/L,36.10 U/mg,and 150.12 mmol/L,respectively.In particular,we found that Xyl4900 could well degrade xylobiose and xylotriose.[Conclusion] Xyl4900 showed good pH stability and tolerance to xylose and salt,and thus could be used in hemicellulose degradation and other industrial production practices.