ArgR and AhrC are both required for regulation of arginine metabolism in Lactococcus lactis
ArgR and AhrC are both required for regulation of arginine metabolism in Lactococcus lactis
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DOI：
10.1128/jb.186.4.1147-1157.2004
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发表时间：
2004-02-01
影响因子：
3.2
通讯作者：
Kok, J
中科院分区：
文献类型：
--
作者：
Larsen, R;Buist, G;Kok, J
DNA结合蛋白ArgR和AhrC分别是调节大肠杆菌和枯草芽孢杆菌精氨酸代谢所必需的。这些调节剂的独特性质是它们形成六聚体蛋白复合物，介导精氨酸生物合成途径的抑制以及精氨酸分解代谢途径的激活。乳酸乳球菌的gltS-argE操纵子编码谷氨酸或精氨酸转运蛋白和乙酰鸟氨酸脱乙酰酶，其催化精氨酸生物合成途径中的重要步骤。通过随机整合敲除筛选，我们发现去阻遏突变体在argR和ahrC等中具有ISSI整合。从乳酸乳球菌乳酸亚种中构建了单调节子和双调节子缺失突变体。cremoris MG 1363.精氨酸生物合成操纵子argCJDBF、argGH和gltS-argE被argR和ahrC的产物抑制。此外，精氨酸分解代谢arcABD 1C 1C 2 TD 2操纵子被ahrC的产物激活，但不被argR的产物激活。argCJDBF操纵子启动子的表达在单突变体和双突变体中达到相似的水平，表明调节剂是相互依赖的，不能相互补充。同时，它们似乎也具有不同的功能，因为只有AhrC参与精氨酸催化剂的激活。这是第一个研究，其中两个同源精氨酸调节剂被证明是参与精氨酸调节的原核生物，代表了一个不寻常的调节机制。
The DNA binding proteins ArgR and AhrC are essential for regulation of arginine metabolism in Escherichia Coli and Bacillus subtilis, respectively. A unique property of these regulators is that they form hexameric protein complexes, mediating repression of arginine biosynthetic pathways as well as activation of arginine catabolic pathways. The gltS-argE operon of Lactococcus lactis encodes a putative glutamate or arginine transport protein and acetylornithine deacetylase, which catalyzes an important step in the arginine biosynthesis pathway. By random integration knockout screening we found that derepression mutants had ISSI integrations in, among others, argR and ahrC. Single as well as double regulator deletion mutants were constructed from Lactococcus lactis subsp. cremoris MG1363. The three arginine biosynthetic operons argCJDBF, argGH, and gltS-argE were shown to be repressed by the products of argR and ahrC. Furthermore, the arginine catabolic arcABD1C1C2TD2 operon was activated by the product of ahrC but not by that of argR. Expression from the promoter of the argCJDBF operon reached similar levels in the single mutants and in the double mutant, suggesting that the regulators are interdependent and not able to complement each other. At the same time, they also appear to have different functions, as only AhrC is involved in activation of arginine catabolism. This is the first study where two homologous arginine regulators are shown to be involved in arginine regulation in a prokaryote, representing an unusual mechanism of regulation.