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Study on Two-Component Signal Transduction System in an Intracellular Symbiotic Bacterium

胞内共生菌双组分信号转导系统的研究

基本信息

批准号：
10680598
负责人：
MORIOKA Mizue
金额：
$ 2.18万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10680598/
关键词：
symbiosis symbionin two-component system signal transduction histone H1 sensor molecule PTS ptsH-ptsl-cγr 糖質輸送 HPK HPr 分子シヤペロン

项目摘要

Symbionin, a GroEL homologous molecular chaperone produced by Buchnera, an intracellular symbiotic bacterium of aphids, is not only a molecular chaperone but also a novel phosphocarrier protein, suggesting that this protein plays a key role in 'the signal transducing system specific to the bacterium living in an intracellular environment. This promoted me to look into Buchnera phosphocarrier proteins such as "sensor molecule or histidine protein kinase (HPK)" of the two-component signal transducing system and "histidine-containing phosphocarrier protein (HPR) " of phosphotransferase system (PTS) that may be shared in common with other free-living bacteria, and the following results were obtained.1. A 25-kDa protein that is able to accept the phosphoryl moiety of phosphorylated symbionin was identified as histone H1. Buchnera histone H1 is extracted with 5% PCA like eukaryotic histones and also retains the DNA-binding activity. The gene for Buchnera histone H1 was cloned and the full amino acid sequence was deduced from its nucleotide sequence. This is the first report of the prokaryotic histone H1. In contrast, no evidence was obtained for the presence of sensor kinases of the two-component system in Buchnera, which are generally found in many free-living bacteria. It is possible that the lack of sensor kinases in Buchnera genome is compensated for by multifunctional symbionin in this symbiotic bacterium.2. I successfully identified ptsH-ptsl-ccr and provide the evidence that these three genes are actively expressed in Buchnera cells. Also, it was demonstrated that "Enzyme I" is auto-catalytically phopshorylated by phosphoenolpyruvate (PEP), but not by ATP, suggesting that phosphotransferase system (PTS) is also actively functioning in Buchnera cells.

共生素（Symbionin）是蚜虫胞内共生细菌Buchnera产生的GroEL同源分子伴侣，它不仅是一种分子伴侣，而且是一种新的磷载体蛋白，表明该蛋白在胞内共生细菌特有的信号转导系统中起着关键作用。这促使我研究Buchnera的磷酸载体蛋白，如双组分信号转导系统的“传感分子或组氨酸蛋白激酶（HPK）”和磷酸转移酶系统（PTS）的“含组氨酸的磷酸载体蛋白（HPR）“，这些蛋白可能与其他自由生活的细菌共有，并获得了以下结果。1.一个25 kDa的蛋白质，能够接受磷酸化共生蛋白的磷酰基部分被确定为组蛋白H1。Buchnera组蛋白H1与真核组蛋白一样用5%PCA提取，并且还保留DNA结合活性。克隆了Buchnera组蛋白H1的基因，并从其核苷酸序列推导出完整的氨基酸序列。这是首次报道的原核组蛋白H1。相比之下，没有证据表明Buchnera中存在双组分系统的传感器激酶，这些激酶通常存在于许多自由生活的细菌中。Buchnera基因组中传感激酶的缺失可能被该共生菌中的多功能共生素所弥补.我成功地鉴定了ptsH-ptsl-ccr，并提供了这三个基因在Buchnera细胞中活跃表达的证据。此外，证明了“酶I”被磷酸烯醇丙酮酸（PEP）自催化磷酸化，但不被ATP自催化磷酸化，表明磷酸转移酶系统（PTS）也在Buchnera细胞中活跃地发挥作用。