2,20-Bipyridine(2,20-BiPy)is an attractive core structure present in a number of biologically active natural products,including the structurally related antibiotics caerulomycins(CAEs)and collismycins(COLs).Their bios...2,20-Bipyridine(2,20-BiPy)is an attractive core structure present in a number of biologically active natural products,including the structurally related antibiotics caerulomycins(CAEs)and collismycins(COLs).Their biosynthetic pathways share a similar key 2,20-BiPy-L-leucine intermediate,which is desulfurated or sulfurated at C5,arises from a polyketide synthase/nonribosomal peptide synthetase hybrid assembly line.Focusing on the common off-line modification steps,we here report that the removal of the“auxiliary”L-leucine residue relies on the metallo-dependent amidohydrolase activity of CaeD or ColD.This activity leads to the production of similar 2,20-BiPy carboxylate products that then receive an oxime functionality that is characteristic for both CAEs and COLs.Unlike many metallo-dependent amidohydrolase superfamily proteins that have been previously reported,these proteins(particularly CaeD)exhibited a strong zinc ion-binding capacity that was proven by site-specific mutagenesis studies to be essential to proteolytic activity.The kinetics of the conversions that respectively involve CaeD and ColD were analyzed,showing the differences in the efficiency and substrate specificity of these two proteins.These findings would generate interest in the metallo-dependent amidohydrolase superfamily proteins that are involved in the biosynthesis of bioactive natural products.展开更多
Plant-based beverages are an alternative to traditional cow milk due to intolerances and allergies as well as for ethical and environmental concerns.Nonetheless,raw materials used in the manufacture of these products ...Plant-based beverages are an alternative to traditional cow milk due to intolerances and allergies as well as for ethical and environmental concerns.Nonetheless,raw materials used in the manufacture of these products are at risk of mycotoxin contamination,being ochratoxin A(OTA)one of the mycotoxins detected.Recently,microbial enzymes have been described,some of them from microorganisms with GRAS(Generally Recognized As Safe)or QPS(Qualified Presumption of Safety)status,able to hydrolyze OTA into OTα,a much less-toxic compound.Since the use of lactic acid bacteria for the fermentation of plant-based beverages improved their nutritional and sensory properties,in this study lactic acid bacteria expressing microbial amidohydrolases from food safe microorganisms were used to ferment two plant-based beverages.Legume-based(soy)and cereal-based(oat)beverages artificially contaminated with OTA were fermented with three lactic acid bacteria strains(Lacti-lactobacillus sakei DSM 15831T Limosilactobacillus fermentum INIA 584L,and Limosilactobacillus reuteri INIA P572)expressing OTA-hydrolyzing enzymes from Aspergillus niger(AnOTA)and Brevibacterium linens(BlOTA).The OTA added to both beverages was greatly degraded during fermentation with the lactic acid bacteria assayed.The OTA-detoxification activity observed could be related to the composition and pH of the fermented beverage.The lower pH achieved in fermented oat,probably due to its high fermentable carbohydrate composition,reduced OTA-degrading activity of AnOTA ochratoxinase,mainly in Lactilactobacillus sakei.This first approach to explore OTA reduction in plant-based beverages paves the way for future applications of improved enzymes produced in food-grade expression systems.展开更多
基金This workwas supported in part by grants from NSFC(21472231,21520102004,31430005,and 81302674)CAS(SQYZDJ-SSWSLH1037 and XDB20020200)+1 种基金STCM(14JC1407700 and 15JC1400400)K.C.Wong Education Foundation and Chang-Jiang Scholars Program of China.
文摘2,20-Bipyridine(2,20-BiPy)is an attractive core structure present in a number of biologically active natural products,including the structurally related antibiotics caerulomycins(CAEs)and collismycins(COLs).Their biosynthetic pathways share a similar key 2,20-BiPy-L-leucine intermediate,which is desulfurated or sulfurated at C5,arises from a polyketide synthase/nonribosomal peptide synthetase hybrid assembly line.Focusing on the common off-line modification steps,we here report that the removal of the“auxiliary”L-leucine residue relies on the metallo-dependent amidohydrolase activity of CaeD or ColD.This activity leads to the production of similar 2,20-BiPy carboxylate products that then receive an oxime functionality that is characteristic for both CAEs and COLs.Unlike many metallo-dependent amidohydrolase superfamily proteins that have been previously reported,these proteins(particularly CaeD)exhibited a strong zinc ion-binding capacity that was proven by site-specific mutagenesis studies to be essential to proteolytic activity.The kinetics of the conversions that respectively involve CaeD and ColD were analyzed,showing the differences in the efficiency and substrate specificity of these two proteins.These findings would generate interest in the metallo-dependent amidohydrolase superfamily proteins that are involved in the biosynthesis of bioactive natural products.
基金financially supported by grant PID-2021-123291OB-I00 funded by MCIN/AEI/10.13039/501100011033by ERDF A way of making Europe+1 种基金a recipient of the PRE2018-083862 FPI contract funded by MCIN/AEI/10.13039/501100011033by ESF Investing in your future.
文摘Plant-based beverages are an alternative to traditional cow milk due to intolerances and allergies as well as for ethical and environmental concerns.Nonetheless,raw materials used in the manufacture of these products are at risk of mycotoxin contamination,being ochratoxin A(OTA)one of the mycotoxins detected.Recently,microbial enzymes have been described,some of them from microorganisms with GRAS(Generally Recognized As Safe)or QPS(Qualified Presumption of Safety)status,able to hydrolyze OTA into OTα,a much less-toxic compound.Since the use of lactic acid bacteria for the fermentation of plant-based beverages improved their nutritional and sensory properties,in this study lactic acid bacteria expressing microbial amidohydrolases from food safe microorganisms were used to ferment two plant-based beverages.Legume-based(soy)and cereal-based(oat)beverages artificially contaminated with OTA were fermented with three lactic acid bacteria strains(Lacti-lactobacillus sakei DSM 15831T Limosilactobacillus fermentum INIA 584L,and Limosilactobacillus reuteri INIA P572)expressing OTA-hydrolyzing enzymes from Aspergillus niger(AnOTA)and Brevibacterium linens(BlOTA).The OTA added to both beverages was greatly degraded during fermentation with the lactic acid bacteria assayed.The OTA-detoxification activity observed could be related to the composition and pH of the fermented beverage.The lower pH achieved in fermented oat,probably due to its high fermentable carbohydrate composition,reduced OTA-degrading activity of AnOTA ochratoxinase,mainly in Lactilactobacillus sakei.This first approach to explore OTA reduction in plant-based beverages paves the way for future applications of improved enzymes produced in food-grade expression systems.
