| 1 | 赖氨酸脱羧酶分子改造及其催化合成戊二胺显示文摘1,5-戊二胺(戊二胺)具有良好的生物活性,广泛应用在农业、医药以及工业等领域。赖氨酸脱羧酶可以催化L-赖氨酸生产戊二胺,为了提高赖氨酸脱羧酶催化合成戊二胺的效率,首先在大肠杆菌中克隆表达了粘质沙雷氏菌来源的赖氨酸脱羧酶(SmcadA)。生化特征表明,SmcadA最适催化pH为6.0,最适催化温度约为40℃。随后对SmcadA的第348位氨基酸进行了突变研究,筛选获得了催化效率显著提高的突变体Gly348Ala,主要原因是该突变导致蛋白中氨基酸残基和底物之间相互作用的氢键数增加,从而影响其催化效率。最后,对重组菌株细胞进行了戊二胺合成研究,催化反应25 h,含有突变体Gly348Ala的重组菌细胞可以催化合成218.2 g/L戊二胺,野生型SmcadA重组菌仅能催化合成159.2 g/L戊二胺。该研究结果为工业化酶催化合成戊二胺提供了借鉴。 | OSIRE Tolbert 杨套伟 乔郅钠 孙杨 徐美娟 张显 邵明龙 饶志明 | 2022 | 食品与发酵工业2022，48，1： | 3 |
| 2 | Comparative transcriptome analysis reveals metabolic regulation of prodigiosin in Serratia marcescens显示文摘Prodigiosin is a secondary metabolite mainly produced at 30°C in Serratia marcescens,but it can hardly be synthetized at 37°C or higher.In this study,we provide insight into the metabolic regulation of prodigiosin synthesis in response to temperature through transcriptome sequencing.The analysis of the function of differentially expressed genes suggested that temperature resulted in significant alteration of the metabolic pathways between 30 and 37°C.Specifically,30°C favored transcriptional expression of the pig gene cluster.At the same time,the carbon flux was redistributed to pathways of pyruvate,proline,serine,especially homoserine,cystathionine,homocysteine,methionine,and s-adenosylmethionine metabolism,all involved in prodigiosin biosynthesis,and was finally increased towards the prodigiosin synthesis pathway in S.marcescens at 30°C.Interestingly,results further confirmed increased transcriptional level of five regulators(LuxS,RpoS,Hfq,EepR,CRP),and decreased content of hexS through qPCR.Finally,successful co-overexpression of mmuM and metK,related to homocysteine,methionine,and s-adenosylmethionine metabolism,in the chromosome of JNB5-1(JNB5-1/MK)resulted in increased prodigiosin titer up to 7.57 g/L in JNB5-1/MK at 30°C,which was 41.2%higher than that in JNB5-1.Our transcriptome analysis provides further insight into the strain’s response to temperature changes at the transcription level,which is of great significance for improving the production of prodigiosin. | Yang Sun Lijun Wang Tolbert Osire Weilai Fu Ganfeng Yi Shang-Tian Yang Taowei Yang Zhiming Rao | 2021 | Systems Microbiology and Biomanufacturing2021，1，3： | 0 |
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