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( Shenghu Zhou ),( Tingting Hao ),( Jingwen Zhou ) 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.10
Flavonoids have diverse biological functions in human health. All flavonoids contain a common 2-phenyl chromone structure (C6-C3-C6) as a scaffold. Hence, in using such a scaffold, plenty of highvalue-added flavonoids can be synthesized by chemical or biological catalyzation approaches. (2S)-Naringenin is one of the most commonly used flavonoid scaffolds. However, biosynthesizing (2S)-naringenin has been restricted not only by low production but also by the expensive precursors and inducers that are used. Herein, we established an induction-free system to de novo biosynthesize (2S)-naringenin in Escherichia coli. The tyrosine synthesis pathway was enhanced by overexpressing feedback inhibition-resistant genes (aroG<sup>fbr</sup> and tyrA<sup>fbr</sup>) and knocking out a repressor gene (tyrR). After optimizing the fermentation medium and conditions, we found that glycerol, glucose, fatty acids, potassium acetate, temperature, and initial pH are important for producing (2S)-naringenin. Using the optimum fermentation medium and conditions, our best strain, Nar-17LM1, could produce 588 mg/l (2S)-naringenin from glucose in a 5-L bioreactor, the highest titer reported to date in E. coli.
Genetically Encoded Biosensor Engineering for Application in Directed Evolution
Mao Yin,Huang Chao,Zhou Xuan,Han Runhua,Deng Yu,Zhou Shenghu 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.10
Although rational genetic engineering is nowadays the favored method for microbial strain improvement, building up mutant libraries based on directed evolution for improvement is still in many cases the better option. In this regard, the demand for precise and efficient screening methods for mutants with high performance has stimulated the development of biosensor-based highthroughput screening strategies. Genetically encoded biosensors provide powerful tools to couple the desired phenotype to a detectable signal, such as fluorescence and growth rate. Herein, we review recent advances in engineering several classes of biosensors and their applications in directed evolution. Furthermore, we compare and discuss the screening advantages and limitations of two-component biosensors, transcription-factor-based biosensors, and RNA-based biosensors. Engineering these biosensors has focused mainly on modifying the expression level or structure of the biosensor components to optimize the dynamic range, specificity, and detection range. Finally, the applications of biosensors in the evolution of proteins, metabolic pathways, and genome-scale metabolic networks are described. This review provides potential guidance in the design of biosensors and their applications in improving the bioproduction of microbial cell factories through directed evolution.
HCBP6 upregulates human SREBP1c expression by binding to C/EBPβ-binding site in the SREBP1c promoter
( Xueliang Yang ),( Ming Han ),( Shunai Liu ),( Xiaoxue Yuan ),( Xiaojing Liu ),( Shenghu Feng ),( Li Zhou ),( Yaru Li ),( Hongping Lu ),( Jun Cheng ),( Shumei Lin ) 생화학분자생물학회(구 한국생화학분자생물학회) 2018 BMB Reports Vol.51 No.1
Sterol regulatory element-binding protein-1c (SREBP1c) plays an important role in triglyceride (TG) homeostasis. Although our previous study showed that hepatitis C virus core-binding protein 6 (HCBP6) regulates SREBP1c expression to maintain intracellular TG homeostasis, the mechanism underlying this regulation is unclear. In the present study, we found that HCBP6 increased intracellular TG levels by upregulating SREBP1c expression. HCBP6 increased SREBP1c transcription by directly binding to the SREBP1c promoter (at the -139- to +359-bp region). Moreover, we observed that HCBP6 interacted with C/EBPβ-binding site in the SREBP1c promoter both in vitro and in vivo. These results indicate that HCBP6 upregulates human SREBP1c expression by binding to the C/EBPβ-binding site in the SREBP1c promoter. [BMB Reports 2018; 51(1): 33-38]