Currently, the biosynthesis of nanomaterials by organisms is attracting considerable attention because of the sustainable and environmentally friendly nature of the reactions involved in this process compared with tho...Currently, the biosynthesis of nanomaterials by organisms is attracting considerable attention because of the sustainable and environmentally friendly nature of the reactions involved in this process compared with those in the conventional nanomaterial synthesis. However, the manipulation and control of nanomaterial biosynthesis remain difficult because of the lack of knowledge about the biosynthetic mechanisms. In the present study, we elucidated the selenium （Se）-precursor and Se metabolic flux in the biosynthesis of cadmium-selenium quantum dots （CdSe QDs） in Saccharomyces cerevisiae and improved the cells＇ ability to biosynthesize CdSe QDs through gene modification based on the regulation mechanism. By deleting the genes involved in Se metabolism and measuring seleno-amino acids, we identified selenocysteine （SeCys） as the primary Se-precursor in the intracellular biosynthesis of CdSe QDs. Further studies demonstrated that the selenomethionine （SeMet）-to-SeCys pathway regulates CdSe QD biosynthesis. Knowledge of the regulatory pathway allowed us to enhance SeMet synthesis by overexpression of the MET6 gene, and an increased CdSe QD yield was realized in the engineered cells. Understanding the mechanism of CdSe QD biosynthesis helped to determine the relationship between nanocrystal formation and biological processes, and offers a new perspective to manipulation of nanomaterial biosynthesis.展开更多
The natural transformation of Escherichia coli is a novel and recently developed system that has significance for genetic studies and the biological safety of genetic engineering.However,the mechanisms of transformati...The natural transformation of Escherichia coli is a novel and recently developed system that has significance for genetic studies and the biological safety of genetic engineering.However,the mechanisms of transformation,including development of competence and DNA uptake,are not thoroughly understood.In this study,we demonstrated the effect of the general stress response regulator RpoS,which has been associated with E.coli transformation,on natural transformation performed in an‘‘open system’’.We find that RpoS is required for natural transformation but not to artificial transformation and RpoS mainly affect transformation in the liquid culture prior to plating.In the liquid culture,RpoS over-expression promotes natural transformation in early exponential phase and static incubation accumulates RpoS and promotes transformation to a limited extent.These findings provide detailed understanding of RpoS function on natural transformation.展开更多
基金This work was supported by the National Natural Science Foundation of China （NSFC） （Nos. 21272182 and 31570090） and the National Basic Research Program of China （973 Program） （No. 2013CB933904）. This project is partially supported by the Chinese 111 Project （No. B06018）, the National Infrastructure of Natural Resources for Science and Technology Program of China （No. NIMR-2017-8）, the National Fund for Fostering Talents in Basic Sciences （No. J1103513）, and the Laboratory （Innovative） Research Fund of Wuhan University. We are grateful to Prof. Yang Wenchao for his generous gift of Probe 3.
文摘Currently, the biosynthesis of nanomaterials by organisms is attracting considerable attention because of the sustainable and environmentally friendly nature of the reactions involved in this process compared with those in the conventional nanomaterial synthesis. However, the manipulation and control of nanomaterial biosynthesis remain difficult because of the lack of knowledge about the biosynthetic mechanisms. In the present study, we elucidated the selenium （Se）-precursor and Se metabolic flux in the biosynthesis of cadmium-selenium quantum dots （CdSe QDs） in Saccharomyces cerevisiae and improved the cells＇ ability to biosynthesize CdSe QDs through gene modification based on the regulation mechanism. By deleting the genes involved in Se metabolism and measuring seleno-amino acids, we identified selenocysteine （SeCys） as the primary Se-precursor in the intracellular biosynthesis of CdSe QDs. Further studies demonstrated that the selenomethionine （SeMet）-to-SeCys pathway regulates CdSe QD biosynthesis. Knowledge of the regulatory pathway allowed us to enhance SeMet synthesis by overexpression of the MET6 gene, and an increased CdSe QD yield was realized in the engineered cells. Understanding the mechanism of CdSe QD biosynthesis helped to determine the relationship between nanocrystal formation and biological processes, and offers a new perspective to manipulation of nanomaterial biosynthesis.
基金supported by the National Basic Research Program of China(2013CB933904)the National Natural Science Foundation of China(30971573,21272182)the Science Fund for Creative Research Groups of NSFC(20921062)
文摘The natural transformation of Escherichia coli is a novel and recently developed system that has significance for genetic studies and the biological safety of genetic engineering.However,the mechanisms of transformation,including development of competence and DNA uptake,are not thoroughly understood.In this study,we demonstrated the effect of the general stress response regulator RpoS,which has been associated with E.coli transformation,on natural transformation performed in an‘‘open system’’.We find that RpoS is required for natural transformation but not to artificial transformation and RpoS mainly affect transformation in the liquid culture prior to plating.In the liquid culture,RpoS over-expression promotes natural transformation in early exponential phase and static incubation accumulates RpoS and promotes transformation to a limited extent.These findings provide detailed understanding of RpoS function on natural transformation.
