The application of the valuable natural product thaxtomin A,a potent bioherbicide from the potato scab pathogenic Streptomyces strains,has been greatly hindered by the low yields from its native producers.Here,we deve...The application of the valuable natural product thaxtomin A,a potent bioherbicide from the potato scab pathogenic Streptomyces strains,has been greatly hindered by the low yields from its native producers.Here,we developed an orthogonal transcription system,leveraging extra-cytoplasmic function(ECF)sigma(σ)factor 17(ECF17)and its cognate promoter Pecf17,to express the thaxtomin gene cluster and improve the production of thaxtomin A.The minimal Pecf17 promoter was determined,and a Pecf17 promoter library with a wide range of strengths was constructed.Furthermore,a cumate inducible system was developed for precise temporal control of the ECF17 transcription system in S.venezuelae ISP5230.Theoretically,the switchable ECF17 transcription system could reduce the unwanted influences from host and alleviate the burdens introduced by overexpression of heterologous genes.The yield of thaxtomin A was significantly improved to 202.1±15.3μg/mL using the switchable ECF17 transcription system for heterologous expression of the thaxtomin gene cluster in S.venezuelae ISP5230.Besides,the applicability of this transcription system was also tested in Streptomyces albus J1074,and the titer of thaxtomin A was raised to as high as 239.3±30.6μg/mL.Therefore,the inducible ECF17 transcription system could serve as a complement of the generally used transcription systems based on strong native constitutive promoters and housekeepingσfactors for the heterologous expression of valuable products in diverse Streptomyces hosts.展开更多
Cyclodipeptides are diverse chemical scaffolds that show a broad range of bioactivities relevant for medicine,agriculture,chemical catalysis,and material sciences.Cyclodipeptides can be synthesized enzymatically throu...Cyclodipeptides are diverse chemical scaffolds that show a broad range of bioactivities relevant for medicine,agriculture,chemical catalysis,and material sciences.Cyclodipeptides can be synthesized enzymatically through two unrelated enzyme families,non-ribosomal peptide synthetases(NRPS)and cyclodipeptide synthases(CDPSs).The chemical diversity of cyclodipeptides is derived from the two amino acid side chains and the modification of those side-chains by cyclodipeptide tailoring enzymes.While a large spectrum of chemical diversity is already known today,additional chemical space-and as such potential new bioactivities-could be accessed by exploring yet undiscovered NRPS and CDPS gene clusters as well as via engineering.Further,to exploit cyclodipeptides for applications,the low yield of natural biosynthesis needs to be overcome.In this review we summarize current knowledge on NRPS and CDPS-based cyclodipeptide biosynthesis,engineering approaches to further diversity the natural chemical diversity as well as strategies for high-yield production of cyclodipeptides,including a discussion of how advancements in synthetic biology and metabolic engineering can accelerate the translational potential of cyclodipeptides.展开更多
基金supported by the National Key Research and Development Program of China[2018YFA0900700]Natural Science Foundation of China[31900901 and 31500069]+1 种基金the Chinese Academy of Sciences[No.QYZDB-SSW-SMC050,No.XDPB1801 of the Strategic Priority Research Program]the Shenzhen Science and Technology Innovation Committee[No.JCYJ20180507182241844,JCHZ20200005,DWKF20190009].
文摘The application of the valuable natural product thaxtomin A,a potent bioherbicide from the potato scab pathogenic Streptomyces strains,has been greatly hindered by the low yields from its native producers.Here,we developed an orthogonal transcription system,leveraging extra-cytoplasmic function(ECF)sigma(σ)factor 17(ECF17)and its cognate promoter Pecf17,to express the thaxtomin gene cluster and improve the production of thaxtomin A.The minimal Pecf17 promoter was determined,and a Pecf17 promoter library with a wide range of strengths was constructed.Furthermore,a cumate inducible system was developed for precise temporal control of the ECF17 transcription system in S.venezuelae ISP5230.Theoretically,the switchable ECF17 transcription system could reduce the unwanted influences from host and alleviate the burdens introduced by overexpression of heterologous genes.The yield of thaxtomin A was significantly improved to 202.1±15.3μg/mL using the switchable ECF17 transcription system for heterologous expression of the thaxtomin gene cluster in S.venezuelae ISP5230.Besides,the applicability of this transcription system was also tested in Streptomyces albus J1074,and the titer of thaxtomin A was raised to as high as 239.3±30.6μg/mL.Therefore,the inducible ECF17 transcription system could serve as a complement of the generally used transcription systems based on strong native constitutive promoters and housekeepingσfactors for the heterologous expression of valuable products in diverse Streptomyces hosts.
文摘Cyclodipeptides are diverse chemical scaffolds that show a broad range of bioactivities relevant for medicine,agriculture,chemical catalysis,and material sciences.Cyclodipeptides can be synthesized enzymatically through two unrelated enzyme families,non-ribosomal peptide synthetases(NRPS)and cyclodipeptide synthases(CDPSs).The chemical diversity of cyclodipeptides is derived from the two amino acid side chains and the modification of those side-chains by cyclodipeptide tailoring enzymes.While a large spectrum of chemical diversity is already known today,additional chemical space-and as such potential new bioactivities-could be accessed by exploring yet undiscovered NRPS and CDPS gene clusters as well as via engineering.Further,to exploit cyclodipeptides for applications,the low yield of natural biosynthesis needs to be overcome.In this review we summarize current knowledge on NRPS and CDPS-based cyclodipeptide biosynthesis,engineering approaches to further diversity the natural chemical diversity as well as strategies for high-yield production of cyclodipeptides,including a discussion of how advancements in synthetic biology and metabolic engineering can accelerate the translational potential of cyclodipeptides.
