發(fā)布時間：2018-11-18 20:16

【摘要】：鏈霉菌能產(chǎn)生大量具有重要醫(yī)療和商業(yè)價值的天然產(chǎn)物,其中包括了大部分抗生素�？股貙τ诋a(chǎn)生菌普遍具有自身毒性,鏈霉菌為抵抗所合成藥物對自身的傷害,進(jìn)化出多種自身耐藥機(jī)制,藥物外排是其中一種十分重要的機(jī)制。近年來抗生素的合成、調(diào)控、后修飾機(jī)制都得到了深入解析,而抗生素轉(zhuǎn)運(yùn)機(jī)制的研究仍然處于起步階段。本文以一株自行篩選的納他霉素高產(chǎn)工業(yè)菌L10為研究對象,深入解析了納他霉素及其合成前體的轉(zhuǎn)運(yùn)機(jī)制和相關(guān)調(diào)控應(yīng)答機(jī)制。首先,論文證實納他霉素合成基因簇內(nèi)的兩個Ⅲ型ABC轉(zhuǎn)運(yùn)蛋白ScnA和ScnB參與了納他霉素轉(zhuǎn)運(yùn),且ScnA和ScnB能夠分別形成同源二聚體行使納他霉素轉(zhuǎn)運(yùn)功能。除ScnA和ScnB外,我們利用表達(dá)譜芯片篩選出Mfs1、NepⅠ/NepⅡ這2組轉(zhuǎn)運(yùn)蛋白, 其中Mfs1編碼了主要協(xié)助轉(zhuǎn)運(yùn)蛋白超家族蛋白；NepⅠ/NepⅡ共同編碼了I型ABC轉(zhuǎn)運(yùn)蛋白。實驗結(jié)果表明：Mfs1與NepⅠ/Ⅱ能夠與ScnA、 ScnB協(xié)同作用,共同構(gòu)成納他霉素高效轉(zhuǎn)運(yùn)網(wǎng)絡(luò)。進(jìn)一步研究發(fā)現(xiàn),ScnA/B、Mfs1還能夠識別和轉(zhuǎn)運(yùn)納他霉素合成直接前體4,5-脫環(huán)氧納他霉素。另外,進(jìn)化分析結(jié)果表明存在于抗生素合成基因簇外基因編碼的轉(zhuǎn)運(yùn)蛋白可能是廣泛存在的鏈霉菌中的一種自身耐藥機(jī)制。其次,論文系統(tǒng)研究了納他霉素轉(zhuǎn)運(yùn)網(wǎng)絡(luò)的調(diào)控機(jī)制,研究結(jié)果表明,scnA/B受途徑特異性調(diào)控因子ScnRⅡ正調(diào)控,mfs1受TetR家族調(diào)控因子Mfo1負(fù)調(diào)控。當(dāng)細(xì)胞內(nèi)出現(xiàn)納他霉素或其前體累積時, Mfo1會應(yīng)答這種累積,啟動Mfs1高表達(dá),進(jìn)而協(xié)助外排納他霉素及其前體,保護(hù)細(xì)胞免受自身代謝產(chǎn)物損傷。nepⅠ/Ⅱ的調(diào)控機(jī)制取得了初步進(jìn)展,但仍需進(jìn)一步探索和驗證。綜上所述,我們首次在S. chattanoogensis L10中發(fā)現(xiàn)并深入解析了恰塔努加鏈霉菌中納他霉素高效轉(zhuǎn)運(yùn)機(jī)制,揭示了該轉(zhuǎn)運(yùn)網(wǎng)絡(luò)的應(yīng)答調(diào)控機(jī)制。本研究為從轉(zhuǎn)運(yùn)角度解除菌株自身耐藥性提供重要理論依據(jù),并為抗生素生產(chǎn)菌高產(chǎn)改造提供了新思路。
[Abstract]:Streptomyces produces a large number of natural products of important medical and commercial value, including most antibiotics. Antibiotics are generally self-toxic to producing bacteria. Streptomyces has evolved a variety of self-resistance mechanisms to resist the harm of synthetic drugs. Drug efflux is one of the most important mechanisms. In recent years, the mechanism of antibiotic synthesis, regulation and post-modification has been deeply analyzed, but the mechanism of antibiotic transport is still in its infancy. In this paper, the transport mechanism of natamycin and its synthetic precursors and the related regulatory response mechanisms were analyzed with a self-screened industrial strain L10, which was a high-yielding industrial strain of natamycin. Firstly, it was confirmed that ScnA and ScnB, two type 鈪，

本文編號：2341093