近日,，國(guó)際著名雜志Molecular Microbiology在線刊登了德國(guó)研究人員的最新研究成果“An orphan sensor kinase controls quinolone signa production via MexT in Pseudomonas aeruginosa”，文章中,，研究者揭示了銅綠假單胞菌的孤體感應(yīng)激酶(orphan sensor kinase)可以通過轉(zhuǎn)錄調(diào)節(jié)子MexT來控制喹諾酮信號(hào)的分子水平,，最終為銅綠假單胞菌的繁殖以及致病性帶來幫助。
銅綠假單胞菌俗稱綠膿桿菌(Pseudomonas aeruginosa,，PA),，是醫(yī)院常見的重要機(jī)會(huì)致病菌，也是肺纖維囊腫病人慢性感染主要的致病菌,，PA可以寄生在任意合適的環(huán)境中,，可以感染植物,、動(dòng)物以及人類，而且該細(xì)菌可以通過自身基因的調(diào)節(jié)來迅速適應(yīng)所繁殖的情況,，這些基因在細(xì)菌的基因組占到了8.4%,，涉及運(yùn)動(dòng)的基因、吸附的基因,、營(yíng)養(yǎng)攝取的基因,、外排抗生素的基因等。PA在這些基因網(wǎng)絡(luò)的調(diào)控下可以有效地進(jìn)行繁殖并且發(fā)生各種急慢性感染,。
PA可以通過N-?；呓z氨酸內(nèi)酯和2-烷基-4（1H）-喹諾酮（AQ）相關(guān)的細(xì)菌信號(hào)分子構(gòu)筑自己的基因調(diào)控網(wǎng)絡(luò)，盡管對(duì)于細(xì)菌群體感應(yīng)系統(tǒng)調(diào)控的靶基因我們了解得很多,，可是對(duì)于環(huán)境因素是如何影響群體感應(yīng)系統(tǒng)的卻知之甚少,。在文章中，研究者Haussler Susanne在銅綠假單胞菌中識(shí)別了一種混合感應(yīng)激酶可以通過LysR轉(zhuǎn)錄調(diào)節(jié)子MexT來控制AQ信號(hào)分子,，包括細(xì)菌間的信號(hào)分子2-庚基-3-羥基-4（1H）-喹諾酮（該信號(hào)分子和假單胞菌喹諾酮信號(hào)分子相關(guān),，PQS），研究者的研究結(jié)果揭示了銅綠假單胞菌感應(yīng)環(huán)境狀況的一種新的分子機(jī)制,，PA可以通過控制AQ信號(hào)分子以及自身綠膿菌素（pyocyanin）的產(chǎn)量來適應(yīng)各種不適合的環(huán)境,，PA的這種適應(yīng)性對(duì)于自己處在不同環(huán)境中（包括寄生在宿主身上）進(jìn)行繁殖和致病的相關(guān)基因的表達(dá)至關(guān)重要。（生物谷：T.Shen編譯）
doi:10.1111/j.1365-2958.2011.07947.x
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An orphan sensor kinase controls quinolone signal production via MexT in Pseudomonas aeruginosa
Caroline Zaoui1, Jörg Overhage1, Dagmar Löns1, Ariane Zimmermann1, Mathias Müsken1,2, Piotr Bielecki2, Christian Pustelny1, Tanja Becker1, Manfred Nimtz3, Susanne Häussler1,2,*
Pseudomonas aeruginosa employs both N-acylhomoserine lactone and 2-alkyl-4(1H)-quinolone (AQ)-mediated interbacterial signalling for the orchestration of a genome-wide gene regulatory network. Despite the many advances that have been made in understanding the target genes of quorum sensing regulation, little is known on how quorum sensing systems are influenced by environmental cues. In this study, we show that AQ production is modulated by an orphan P. aeruginosa sensor kinase. Transcriptional studies of the sensor kinase (MxtR) mutant demonstrated that an induced expression of MexT, a LysR-type transcriptional regulator, largely determined the global transcriptional profile. Thereby, overexpression of the MexT-regulated MexEF-OprN efflux pump led to a delayed expression of the AQ biosynthetic genes and of AQ-dependent virulence factors. Furthermore, we demonstrated that autophosphorylation of MxtR was inhibited by ubiquinone, the central electron carrier of respiration in in vitro experiments. Our results elucidate on a mechanism by which P. aeruginosa senses environmental conditions and adapts by controlling the production of interbacterial AQ signal molecules. A regulatory function of a sensor kinase may indicate that there is a pre-emptive role of adaptation mechanisms that are turned on under distinct environmental conditions and that are important for efficient colonization and pathogenesis.
