Tavori H, Kimmel Y, Barak Z
J Bacteriol. 1981 May;146(2):676-83. doi: 10.1128/jb.146.2.676-683.1981.
A variety of leucine-containing peptides (LCP), Phe-Leu, Gly-Leu, Pro-Leu, Ala-Leu, Ala-Leu-Lys, Leu-Phe-Ala, Leu-Leu-Leu, and Leu-Gly-Gly, inhibited the growth of a prototrophic strain of Escherichia coli K-12 at concentrations between 0.05 and 0.28 mM. Toxicity requires normal uptake of peptides. When peptide transport was impaired by mutations, strains became resistant to the respective LCP. Inhibition of growth occurred immediately after the addition of LCP, and was relieved when 0.4 mM isoleucine was added. The presence of Gly-Leu in the medium correlated with the inhibition of growth, and the bacteria began to grow at the normal rate 70 min after Gly-Leu became undetectable. Disappearance of the peptide corresponded with the appearance of free leucine and glycine in the medium. The concentration of leucine inside the LCP-treated bacteria was higher than that in the leucine-treated and the control cultures. We suggest that entry of LCP into the cells via peptide transport systems circumvents the regulation of leucine transport, thereby causing abnormality high concentrations of leucine inside the cells. This accumulation of leucine interferes with the biosynthesis of isoleucine and inhibits the growth of the bacteria.
多种含亮氨酸的肽（LCP），如苯丙氨酸 - 亮氨酸、甘氨酸 - 亮氨酸、脯氨酸 - 亮氨酸、丙氨酸 - 亮氨酸、丙氨酸 - 亮氨酸 - 赖氨酸、亮氨酸 - 苯丙氨酸 - 丙氨酸、亮氨酸 - 亮氨酸 - 亮氨酸和亮氨酸 - 甘氨酸 - 甘氨酸，在浓度为0.05至0.28 mM之间时可抑制大肠杆菌K - 12原养型菌株的生长。毒性需要肽的正常摄取。当肽转运因突变而受损时，菌株对相应的LCP产生抗性。添加LCP后立即出现生长抑制，添加0.4 mM异亮氨酸后抑制解除。培养基中甘氨酸 - 亮氨酸的存在与生长抑制相关，当甘氨酸 - 亮氨酸检测不到70分钟后，细菌开始以正常速率生长。肽的消失与培养基中游离亮氨酸和甘氨酸的出现相对应。经LCP处理的细菌内亮氨酸的浓度高于经亮氨酸处理的细菌和对照培养物中的浓度。我们认为，LCP通过肽转运系统进入细胞规避了亮氨酸转运的调节，从而导致细胞内亮氨酸浓度异常升高。这种亮氨酸的积累干扰了异亮氨酸的生物合成并抑制了细菌的生长。
