Acta Pharmaceutica Sinica B (May 2019)

Combinatorial mutation on the β-glycosidase specific to 7-β-xylosyltaxanes and increasing the mutated enzyme production by engineering the recombinant yeast

  • Jing-Jing Chen,
  • Xiao Liang,
  • Fen Wang,
  • Yan-Hua Wen,
  • Tian-Jiao Chen,
  • Wan-Cang Liu,
  • Ting Gong,
  • Jin-Ling Yang,
  • Ping Zhu

Journal volume & issue
Vol. 9, no. 3
pp. 626 – 638

Abstract

Read online

Taxol is a “blockbuster” antitumor drug produced by Taxus species with extremely low amount, while its analogue 7-β-xylosyl-10-deacetyltaxol is generally much higher in the plants. Both the fungal enzymes LXYL-P1−1 and LXYL-P1−2 can convert 7-β-xylosyl-10-deacetyltaxol into 10-deacetyltaxol for Taxol semi-synthesis. Of them, LXYL-P1−2 is twice more active than LXYL-P1−1, but there are only 11 significantly different amino acids in terms of the polarity and acidic-basic properties between them. In this study, single and multiple site-directed mutations at the 11 sites from LXYL-P1−1 to LXYL-P1−2 were performed to define the amino acids with upward bias in activities and to acquire variants with improved catalytic properties. Among all the 17 mutants, E12 (A72T/V91S) was the most active and even displayed 2.8- and 3-fold higher than LXYL-P1−2 on β-xylosidase and β-glucosidase activities. The possible mechanism for such improvement was proposed by homology modeling and molecular docking between E12 and 7-β-xylosyl-10-deacetyltaxol. The recombinant yeast GS115-P1E12-7 was constructed by introducing variant E12, the molecular chaperone gene pdi and the bacterial hemoglobin gene vhb. This engineered yeast rendered 4 times higher biomass enzyme activity than GS115-3.5K-P1−2 that had been used for demo-scale fermentation. Thus, GS115-P1E12-7 becomes a promising candidate to replace GS115-3.5K-P1−2 for industrial purpose. KEY WORDS: β-Glycosidases, Combinatorial mutation, Improved catalytic property, Molecular docking, Engineered yeast, Taxol