Signalling by the global regulatory molecule ppGpp in bacteria and chloroplasts of land plants.
Signalling by the global regulatory molecule ppGpp in bacteria and chloroplasts of land plants.
复制标题
陆地植物细菌和叶绿体中全局调节分子 ppGpp 发出的信号。
DOI：
10.1111/j.1438-8677.2011.00484.x
复制
发表时间：
2011
期刊：
影响因子：
3.9
通讯作者：
Yuhta Nomura
中科院分区：
文献类型：
--
作者：
Y. Tozawa;Yuhta Nomura
过度磷酸化的鸟嘌呤核苷酸ppGpp介导细菌中的严格反应。大肠杆菌中这种反应的生物化学和遗传学研究表明，ppGpp的生物合成由两种同源酶RelA和SpoT催化。RelA在氨基酸饥饿时被激活，而SpoT除了对营养胁迫有反应外，还对非生物物理胁迫有反应。所有自由生活的细菌，包括革兰氏阳性厚壁菌门，都含有RelA-SpoT同源物（RSH）。此外，最近在包括革兰氏阳性生物枯草芽孢杆菌的细菌亚群中鉴定了新的ppGpp生物合成酶，称为小警报素合成酶（SAS），并且显示仅由ppGpp合成酶结构域组成。研究表明，这些SAS蛋白有助于ppGpp信号在响应压力条件的方式不同的RelA-SpoT酶。SAS蛋白目前似乎总是出现在除了RSH酶在各种组合，但从来没有单独。RSH还在叶绿体中被鉴定，叶绿体是起源于内共生光合细菌的光合真核生物的细胞器。这些叶绿体RSH仅在核DNA中编码并靶向叶绿体。这些发现表明ppGpp可能调节叶绿体功能，类似于细菌中的调节，包括转录和翻译。此外，最近在陆地植物叶绿体中发现了一种新的ppGpp合成酶，该合成酶由于在其COOH末端存在两个EF-手形基序而受到Ca² O的调节。这一发现表明叶绿体中真核生物Ca² A信号和原核生物ppGpp信号之间存在直接联系。关于陆地植物中ppGpp信号的新观察表明，这种信号有助于调节比以前预期的更广泛的细胞功能。
The hyperphosphorylated guanine ribonucleotide ppGpp mediates the stringent response in bacteria. Biochemical and genetic studies of this response in Escherichia coli have shown that the biosynthesis of ppGpp is catalysed by two homologous enzymes, RelA and SpoT. RelA is activated in response to amino acid starvation, and SpoT responds to abiotic physical stress beside nutritional stress. All free-living bacteria, including Gram-positive firmicutes, contain RelA-SpoT homologues (RSH). Further, novel ppGpp biosynthetic enzymes, designated small alarmone synthetases (SASs), were recently identified in a subset of bacteria, including the Gram-positive organism Bacillus subtilis, and were shown to consist only of a ppGpp synthetase domain. Studies suggest that these SAS proteins contribute to ppGpp signalling in response to stressful conditions in a manner distinct from that of RelA-SpoT enzymes. SAS proteins currently appear to always occur in addition to RSH enzymes in various combinations but never alone. RSHs have also been identified in chloroplasts, organelles of photosynthetic eukaryotes that originated from endosymbiotic photosynthetic bacteria. These chloroplast RSHs are exclusively encoded in nuclear DNA and targeted into chloroplasts. The findings suggest that ppGpp may regulate chloroplast functions similar to those regulated in bacteria, including transcription and translation. In addition, a novel ppGpp synthetase that is regulated by Ca²⁺ as a result of the presence of two EF-hand motifs at its COOH terminus was recently identified in chloroplasts of land plants. This finding indicates the existence of a direct connection between eukaryotic Ca²⁺ signalling and prokaryotic ppGpp signalling in chloroplasts. The new observations with regard to ppGpp signalling in land plants suggest that such signalling contributes to the regulation of a wider range of cellular functions than previously anticipated.
登录
查看更多内容
影响因子：
5.6
作者：
Barker, MM;Gaal, T;Gourse, RL
通讯作者：
Gourse, RL
影响因子：
56.9
作者：
JOHNSON, CH;KNIGHT, MR;TREWAVAS, A
通讯作者：
TREWAVAS, A
DOI：
10.1073/pnas.90.21.10066
发表时间：
1993-11
影响因子：
11.1
作者：
Laiqiang Huang;Tom Berkelman;A. Franklin;Neil E. Hoffman
通讯作者：
Laiqiang Huang;Tom Berkelman;A. Franklin;Neil E. Hoffman
影响因子：
2.9
作者：
Lee, Cheng-I;Lakshmi, K. V.;Brudvig, Gary W.
通讯作者：
Brudvig, Gary W.
影响因子：
2.9
作者：
Avarbock, D;Avarbock, A;Rubin, H
通讯作者：
Rubin, H