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Functional diversity of isoprenoid lipids in Methylobacterium extorquens PA1
Molecular Microbiology ( IF 3.6 ) Pub Date : 2021-08-13 , DOI: 10.1111/mmi.14794
Sandra Rizk 1 , Petra Henke 2 , Carlos Santana-Molina 3 , Gesa Martens 2 , Marén Gnädig 1 , Ngoc Anh Nguyen 1 , Damien P Devos 3 , Meina Neumann-Schaal 2 , James P Saenz 1
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Hopanoids and carotenoids are two of the major isoprenoid-derived lipid classes in prokaryotes that have been proposed to have similar membrane ordering properties as sterols. Methylobacterium extorquens contains hopanoids and carotenoids in their outer membrane, making them an ideal system to investigate the role of isoprenoid lipids in surface membrane function and cellular fitness. By genetically knocking out hpnE and crtB we disrupted the production of squalene and phytoene in M. extorquens PA1, which are the presumed precursors for hopanoids and carotenoids respectively. Deletion of hpnE revealed that carotenoid biosynthesis utilizes squalene as a precursor resulting in pigmentation with a C30 backbone, rather than the previously predicted canonical C40 phytoene-derived pathway. Phylogenetic analysis suggested that M. extorquens may have acquired the C30 pathway through lateral gene transfer from Planctomycetes. Surprisingly, disruption of carotenoid synthesis did not generate any major growth or membrane biophysical phenotypes, but slightly increased sensitivity to oxidative stress. We further demonstrated that hopanoids but not carotenoids are essential for growth at higher temperatures, membrane permeability and tolerance of low divalent cation concentrations. These observations show that hopanoids and carotenoids serve diverse roles in the outer membrane of M. extorquens PA1.

中文翻译:

甲基异戊二烯类脂类异戊二烯脂质的功能多样性

Hopanoids 和类胡萝卜素是原核生物中两种主要的类异戊二烯衍生的脂质类别,已被提议具有与甾醇相似的膜排序特性。Methylobacterium extorquens在其外膜中含有藿香类和类胡萝卜素,使其成为研究类异戊二烯脂质在表面膜功能和细胞适应性中的作用的理想系统。通过基因敲除hpnEcrtB,我们破坏了M. extorquens PA1 中角鲨烯和八氢番茄红素的产生,它们分别是藿香类和类胡萝卜素的假定前体。删除hpnE表明类胡萝卜素生物合成利用角鲨烯作为前体,导致色素沉着与 C30骨架,而不是先前预测的规范的 C 40八氢番茄红素衍生途径。系统发育分析表明,M. extorquens可能通过来自Planctomycetes 的横向基因转移获得了C 30途径。令人惊讶的是,类胡萝卜素合成的中断并没有产生任何主要的生长或膜生物物理表型,但对氧化应激的敏感性略有增加。我们进一步证明,藿香而不是类胡萝卜素对于在较高温度下的生长、膜渗透性和对低二价阳离子浓度的耐受性是必不可少的。这些观察结果表明,hopanoids 和类胡萝卜素在M. extorquens PA1的外膜中发挥着不同的作用。
更新日期:2021-08-13
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