Nickels Jonathan D, Poudel Suresh, Chatterjee Sneha, Farmer Abigail, Cordner Destini, Campagna Shawn R, Giannone Richard J, Hettich Robert L, Myles Dean A A, Standaert Robert F, Katsaras John, Elkins James G
Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH, United States.
Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.
Front Microbiol. 2020 May 15;11:914. doi: 10.3389/fmicb.2020.00914. eCollection 2020.
Developing cultivation methods that yield chemically and isotopically defined fatty acid (FA) compositions within bacterial cytoplasmic membranes establishes an experimental platform to study membrane biophysics and cell membrane regulation using novel approaches. Yet before fully realizing the potential of this method, it is prudent to understand the systemic changes in cells induced by the labeling procedure itself. In this work, analysis of cellular membrane compositions was paired with proteomics to assess how the proteome changes in response to the directed incorporation of exogenous FAs into the membrane of . Key findings from this analysis include an alteration in lipid headgroup distribution, with an increase in phosphatidylglycerol lipids and decrease in phosphatidylethanolamine lipids, possibly providing a fluidizing effect on the cell membrane in response to the induced change in membrane composition. Changes in the abundance of enzymes involved in FA biosynthesis and degradation are observed; along with changes in abundance of cell wall enzymes and isoprenoid lipid production. The observed changes may influence membrane organization, and indeed the well-known lipid raft-associated protein flotillin was found to be substantially down-regulated in the labeled cells - as was the actin-like protein MreB. Taken as a whole, this study provides a greater depth of understanding for this important cell membrane experimental platform and presents a number of new connections to be explored in regard to modulating cell membrane FA composition and its effects on lipid headgroup and raft/cytoskeletal associated proteins.
开发能够在细菌细胞质膜内产生化学和同位素定义的脂肪酸（FA）组成的培养方法，建立了一个实验平台，可用于使用新方法研究膜生物物理学和细胞膜调节。然而，在充分实现该方法的潜力之前，谨慎地了解标记过程本身在细胞中引起的系统性变化是很有必要的。在这项工作中，对细胞膜组成的分析与蛋白质组学相结合，以评估蛋白质组如何响应外源性脂肪酸定向掺入细胞膜而发生变化。该分析的主要发现包括脂质头部基团分布的改变，磷脂酰甘油脂质增加，磷脂酰乙醇胺脂质减少，这可能会因膜组成的诱导变化而对细胞膜产生流化作用。观察到参与脂肪酸生物合成和降解的酶丰度发生变化；以及细胞壁酶丰度和类异戊二烯脂质产生的变化。观察到的这些变化可能会影响膜的组织，事实上，在标记细胞中发现与脂质筏相关的著名蛋白质flotillin以及肌动蛋白样蛋白MreB大量下调。总体而言，这项研究为这个重要的细胞膜实验平台提供了更深入的理解，并提出了一些关于调节细胞膜脂肪酸组成及其对脂质头部基团和筏/细胞骨架相关蛋白影响的新联系有待探索。
