氨基酸
生物化学
蛋白质生物合成
背景(考古学)
异亮氨酸
化学
流出
生物
亮氨酸
古生物学
作者
Christine Hook,Natalya S. Eremina,Petr Zaytsev,Daria Varlamova,Nataliya V. Stoynova
出处
期刊:Microorganisms
[MDPI AG]
日期:2022-03-17
卷期号:10 (3): 647-647
被引量:11
标识
DOI:10.3390/microorganisms10030647
摘要
Amino acid transport systems perform important physiological functions; their role should certainly be considered in microbial production of amino acids. Typically, in the context of metabolic engineering, efforts are focused on the search for and application of specific amino acid efflux pumps. However, in addition, importers can also be used to improve the industrial process as a whole. In this study, the protein CycA, which is known for uptake of nonpolar amino acids, was characterized from the viewpoint of regulating its expression and range of substrates. We prepared a cycA-overexpressing strain and found that it exhibited high sensitivity to branched-chain amino acids and their structural analogues, with relatively increased consumption of these amino acids, suggesting that they are imported by CycA. The expression of cycA was found to be dependent on the extracellular concentrations of substrate amino acids. The role of some transcription factors in cycA expression, including of Lrp and Crp, was studied using a reporter gene construct. Evidence for the direct binding of Crp to the cycA regulatory region was obtained using a gel-retardation assay. The enhanced import of named amino acids due to cycA overexpression in the l-isoleucine-producing strain resulted in a significant reduction in the generation of undesirable impurities. This work demonstrates the importance of uptake systems with respect to their application in metabolic engineering.
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