Research Institute for Bioscience Products and Fine Chemicals, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa 210-8681, Japan.
Research Institute for Bioscience Products and Fine Chemicals, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa 210-8681, Japan; Ajinomoto-Genetika Research Institute, 117545 Moscow, Russia.
J Biosci Bioeng. 2020 Jul;130(1):14-19. doi: 10.1016/j.jbiosc.2020.02.007. Epub 2020 Mar 23.
Here, proteins involved in sulfur-containing amino acid uptake in Escherichia coli strains were investigated with the aim of applying the findings in fermentative amino acid production. A search of genes in an l-methionine auxotrophic strain library suggested YecSC as the putative transporter of l-cystathionine. l-Methionine production increased by 15% after amplification of yecSC in producer strains. A candidate protein responsible for l-cysteine uptake was also found by experimentation with multicopy suppressor E. coli strains that recovered from growth defects caused by l-cysteine auxotrophy. Based on the results of an uptake assay, growth using l-cysteine as a sole sulfur source, and sensitivity to l-cysteine toxicity, we proposed that YeaN is an l-cysteine transporter. l-Cysteine production increased by 50% as a result of disrupting yeaN in producer strain. The study of amino acid transporters is valuable to industrialized amino acid production and also sheds light on the role of these transporters in sulfur assimilation.
本文旨在将研究成果应用于发酵生产氨基酸，研究了大肠杆菌菌株中含硫氨基酸摄取相关的蛋白质。对 l-甲硫氨酸营养缺陷型菌株文库中的基因进行搜索，结果表明 YecSC 是 l-胱硫醚的潜在转运蛋白。在生产菌株中扩增 yecSC 后，l-甲硫氨酸的产量提高了 15%。通过对能够从 l-半胱氨酸营养缺陷引起的生长缺陷中恢复的多拷贝抑制型大肠杆菌菌株进行实验，也发现了 l-半胱氨酸摄取的候选蛋白。根据摄取试验、仅用 l-半胱氨酸作为唯一硫源的生长情况以及对 l-半胱氨酸毒性的敏感性，我们提出 YeaN 是 l-半胱氨酸转运蛋白。在生产菌株中敲除 yeaN 后，l-半胱氨酸的产量增加了 50%。对氨基酸转运蛋白的研究对工业化氨基酸生产具有重要意义，也揭示了这些转运蛋白在硫同化中的作用。
