For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of S...For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of Saccharomyces cerevisiae was designed and reconstructed in Escherichia coli.Then,the expression levels of the relevant enzymes were coordinated using a modular approach and gene duplication after the identification of the pyruvate decarboxylase from Candida tropicalis(CtPDC)as the rate-limiting enzymatic step.In situ product removal(ISPR)strategy with XAD4 resins was explored to avoid product inhibition and further improve tyrosol yield.As a result,the titer and conversion rate of tyrosol obtained were 35.7 g·L^(-1) and 93.6%,respectively,in a 3-L bioreactor.Results presented here provide a potential enzymatic process for industrial production of tyrosol from cheap amino acids.展开更多
Huangjiu is known for its unique aroma,primarily attributed to its high concentration ofβ-phenylethanol(ranging from 40 to 130 mg/L).Phenylalanine aminotransferase Aro9p and phenylpyruvate decarboxylase Aro10p are ke...Huangjiu is known for its unique aroma,primarily attributed to its high concentration ofβ-phenylethanol(ranging from 40 to 130 mg/L).Phenylalanine aminotransferase Aro9p and phenylpyruvate decarboxylase Aro10p are key enzymes in theβ-phenylethanol synthetic pathway of Saccharomyces cerevisiae^(HJ).This study examined the enzymatic properties of these two enzymes derived from S.cerevisiae^(HJ)and^(S288C).After substrate docking,Aro9p^(HJ)(-24.05 kJ/mol)and Aro10p^(HJ)(-14.33 kJ/mol)exhibited lower binding free energies compared to Aro9p^(S288C)(-21.93 kJ/mol)and Aro10p^(S288C)(-12.84 kJ/mol).ARO9 and ARO10 genes were heterologously expressed in E.coli BL21.Aro9p,which was purified via affinity chromatography,showed inhibition by L-phenylalanine(L-PHE),but the reaction rate Vmax(Aro9p^(HJ):23.89μmol⋅(min·g)^(-1)>Aro9p^(S288C):21.3μmol⋅(min·g)^(-1))and inhibition constant Ki values(Aro9p^(HJ):0.28 mol L^(-1)>Aro9p^(S288C)0.26 mol L^(-1))indicated that Aro9p from S.cerevisiae^(HJ)was more tolerant to substrate stress during Huangjiu fermentation.In the presence of the same substrate phenylpyruvate(PPY),Aro10p^(HJ)exhibited a stronger affinity than Aro10p^(S288C).Furthermore,Aro9p^(HJ)and Aro10p^(HJ)were slightly more tolerant to the final metabolitesβ-phenylethanol and ethanol,respectively,compared to those from^(S288C).The study suggests that the mutations in Aro9p^(HJ)and Aro10p^(HJ)may contribute to the increasedβ-phenylethanol concentration in Huangjiu.This is the first study investigating enzyme tolerance mechanisms in terms of substrate and product,providing a theoretical basis for the regulation of theβ-phenylethanol metabolic pathway.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities (JUSRP21915)National Natural Science Foundation of China (22008089, 21878126)+2 种基金Provincial Natural Science Foundation of Jiangsu Province(BK20200622)the key technologies Research&Development Program of Jiangsu Province (BE2018623)the National First-Class Discipline Program of Light Industry Technology and Engineering(LITE2018-20)
文摘For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of Saccharomyces cerevisiae was designed and reconstructed in Escherichia coli.Then,the expression levels of the relevant enzymes were coordinated using a modular approach and gene duplication after the identification of the pyruvate decarboxylase from Candida tropicalis(CtPDC)as the rate-limiting enzymatic step.In situ product removal(ISPR)strategy with XAD4 resins was explored to avoid product inhibition and further improve tyrosol yield.As a result,the titer and conversion rate of tyrosol obtained were 35.7 g·L^(-1) and 93.6%,respectively,in a 3-L bioreactor.Results presented here provide a potential enzymatic process for industrial production of tyrosol from cheap amino acids.
基金supported by the National Natural Science Foundation of China(32072205,22138004)Shaoxing Science and Technology Plan Project(2022B43001).
文摘Huangjiu is known for its unique aroma,primarily attributed to its high concentration ofβ-phenylethanol(ranging from 40 to 130 mg/L).Phenylalanine aminotransferase Aro9p and phenylpyruvate decarboxylase Aro10p are key enzymes in theβ-phenylethanol synthetic pathway of Saccharomyces cerevisiae^(HJ).This study examined the enzymatic properties of these two enzymes derived from S.cerevisiae^(HJ)and^(S288C).After substrate docking,Aro9p^(HJ)(-24.05 kJ/mol)and Aro10p^(HJ)(-14.33 kJ/mol)exhibited lower binding free energies compared to Aro9p^(S288C)(-21.93 kJ/mol)and Aro10p^(S288C)(-12.84 kJ/mol).ARO9 and ARO10 genes were heterologously expressed in E.coli BL21.Aro9p,which was purified via affinity chromatography,showed inhibition by L-phenylalanine(L-PHE),but the reaction rate Vmax(Aro9p^(HJ):23.89μmol⋅(min·g)^(-1)>Aro9p^(S288C):21.3μmol⋅(min·g)^(-1))and inhibition constant Ki values(Aro9p^(HJ):0.28 mol L^(-1)>Aro9p^(S288C)0.26 mol L^(-1))indicated that Aro9p from S.cerevisiae^(HJ)was more tolerant to substrate stress during Huangjiu fermentation.In the presence of the same substrate phenylpyruvate(PPY),Aro10p^(HJ)exhibited a stronger affinity than Aro10p^(S288C).Furthermore,Aro9p^(HJ)and Aro10p^(HJ)were slightly more tolerant to the final metabolitesβ-phenylethanol and ethanol,respectively,compared to those from^(S288C).The study suggests that the mutations in Aro9p^(HJ)and Aro10p^(HJ)may contribute to the increasedβ-phenylethanol concentration in Huangjiu.This is the first study investigating enzyme tolerance mechanisms in terms of substrate and product,providing a theoretical basis for the regulation of theβ-phenylethanol metabolic pathway.