LuxS:: its role in central metabolism and the in vitro synthesis of 4-hydroxy-5-methyl-3(2H)-furanone
LuxS:: its role in central metabolism and the in vitro synthesis of 4-hydroxy-5-methyl-3(2H)-furanone
复制标题
DOI：
10.1099/00221287-148-4-909
复制
发表时间：
2002-04-01
期刊：
影响因子：
2.8
通讯作者：
Williams, P
中科院分区：
文献类型：
--
作者：
Winzer, K;Hardie, KR;Williams, P
许多细菌产生细胞外分子，在细胞间通讯中发挥作用。这些分子之一，自诱导剂 2 (Al-2)，首先被描述为由哈维氏弧菌产生的细胞外信号，用于控制荧光素酶的表达。随后，许多细菌已被证明在其培养物上清液中具有 Al-2 活性，并带有 luxS 基因产物，这是 Al-2 合成所需的。在牙龈卟啉单胞菌中，编码 5'-甲硫腺苷/S-腺苷高半胱氨酸核苷酶 (MTA/SAH'ase) 的 luxS 和 pfs 形成操纵子，表明 S-腺苷高半胱氨酸 (SAH) 或 5'-甲硫腺苷 (MTA) 作为 Al-2 生产的底物。大肠杆菌 MG1655 的无细胞提取物（而非 DH5alpha（携带 luxS 移码突变））在添加 SAH（而非 MTA）后能够产生 Al-2 活性。源自 SAH 的 S-核糖基高半胱氨酸 (RH) 也可用作大肠杆菌 MG1655 提取物中的底物。铜绿假单胞菌（一种缺乏 luxS 的细菌）的 RH 补充无细胞提取物仅在引入含有 Por 的质粒后才产生 Al-2 活性。牙龈炎 pfs-luxS 操纵子。此外，还确定了由来自 Por 的纯化 LuxS 蛋白组成的体外系统。牙龈炎、大肠杆菌、脑膜炎奈瑟菌或金黄色葡萄球菌将 RH 转化为同型半胱氨酸和具有 Al-2 活性的化合物。通过质谱分析确定4-羟基-5-甲基-3 (2H)-呋喃酮是该体外反应中形成的主要产物。在大肠杆菌 MG1655 中，T3SH [噬菌体 T3 S-腺苷甲硫氨酸 (SAM) 水解酶] 的表达显着降低了培养物上清液中的 Al-2 活性，表明 Al-2 的产生受到 SAM 依赖性转甲基酶反应中产生的 SAH 量的限制。作者认为 LuxS 蛋白在 SAH 的循环中具有重要的代谢功能。他们还表明，诗篇。铜绿假单胞菌能够消除 Al-2 活性，这意味着该分子可能充当营养物质。在许多细菌中，Al-2 实际上可能代表的不是信号分子，而是在生长早期释放并在生长后期代谢的代谢物。
Many bacteria produce extracellular molecules which function in cell-to-cell communication. One of these molecules, autoinducer 2 (Al-2), was first described as an extracellular signal produced by Vibrio harveyi to control luciferase expression. Subsequently, a number of bacteria have been shown to possess Al-2 activity in their culture supernatants, and bear the luxS gene product, which is required for Al-2 synthesis. In Porphyromonas gingivalis, luxS and pfs, encoding a 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTA/SAH'ase), form an operon, suggesting that S-adenosylhomocysteine (SAH) or 5'-methylthioadenosine (MTA) serves as a substrate for Al-2 production. Cell-free extracts of Escherichia coli MG1655, but not DH5alpha (which carries a luxS frame-shift mutation) were capable of generating Al-2 activity upon addition of SAH, but not MTA. S-Ribosyl-homocysteline (RH) derived from SAH also served as a substrate in E. coli MG1655 extracts. RH-supplemented cell-free extracts of Pseudomonas aeruginosa, a bacterium that lacks luxS, only generated Al-2 activity following the introduction of a plasmid containing the Por. gingivalis pfs-luxS operon. In addition, defined in vitro systems consisting of the purified LuxS proteins from Por. gingivalis, E. coli, Neisseria meningitidis or Staphylococcus aureus converted RH to homocysteine and a compound that exhibits Al-2 activity. 4-Hydroxy-5-methyl-3 (2H)-furanone was identified by mass spectrometry analysis as a major product formed in this in vitro reaction. In E. coli MG1655, expression of T3SH [the bacteriophage T3 S-adenosylmethionine (SAM) hydrolase] significantly reduced Al-2 activity in culture supernatants, suggesting that Al-2 production is limited by the amount of SAH produced in SAM-dependent transmethylase reactions. The authors suggest that the LuxS protein has an important metabolic function in the recycling of SAH. They also show that Ps. aeruginosa, is capable of removing Al-2 activity, implying that this molecule may act as a nutrient. In many bacteria Al-2 may in fact represent not a signal molecule but a metabolite which is released early and metabolized in the later stages of growth.