How membrane viscosity affects respiration In bacteria, energy production by the electron transport chain occurs at cell membranes and can be influenced by the lipid composition of the membrane. Budin et al. used genetic engineering to influence the concentration of unsaturated branched-chain fatty acids and thus control membrane viscosity (see the Perspective by Schon). Experimental measurements and mathematical modeling indicated that rates of respiratory metabolism and rates of cell growth were dependent on membrane viscosity and its effects on diffusion. Experiments on yeast mitochondria also showed similar effects. Maintaining efficient respiration may thus place evolutionary constraints on cellular lipid composition. Science, this issue p. 1186; see also p. 1114 Metabolic engineering of membrane viscosity can regulate respiration rates in Escherichia coli and in yeast mitochondria. Lipid composition determines the physical properties of biological membranes and can vary substantially between and within organisms. We describe a specific role for the viscosity of energy-transducing membranes in cellular respiration. Engineering of fatty acid biosynthesis in Escherichia coli allowed us to titrate inner membrane viscosity across a 10-fold range by controlling the abundance of unsaturated or branched lipids. These fluidizing lipids tightly controlled respiratory metabolism, an effect that can be explained with a quantitative model of the electron transport chain (ETC) that features diffusion-coupled reactions between enzymes and electron carriers (quinones). Lipid unsaturation also modulated mitochondrial respiration in engineered budding yeast strains. Thus, diffusion in the ETC may serve as an evolutionary constraint for lipid composition in respiratory membranes.

中文翻译：

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通过膜脂成分对细胞呼吸的粘性控制

膜粘度如何影响呼吸 在细菌中，电子传递链产生的能量发生在细胞膜上，并且会受到膜脂质成分的影响。布丁等人。使用基因工程来影响不饱和支链脂肪酸的浓度，从而控制膜粘度（参见 Schon 的观点）。实验测量和数学模型表明呼吸代谢率和细胞生长率取决于膜粘度及其对扩散的影响。对酵母线粒体的实验也显示出类似的效果。因此，保持有效的呼吸可能会对细胞脂质组成施加进化限制。科学，这个问题 p。第1186章 另见第。1114 膜粘度的代谢工程可以调节大肠杆菌和酵母线粒体的呼吸速率。脂质成分决定了生物膜的物理特性，并且在生物体之间和生物体内可能会有很大差异。我们描述了能量转换膜在细胞呼吸中的粘度的特定作用。大肠杆菌中的脂肪酸生物合成工程使我们能够通过控制不饱和或支链脂质的丰度，在 10 倍范围内滴定内膜粘度。这些流化脂质严格控制呼吸代谢，这种效应可以用电子传递链 (ETC) 的定量模型来解释，该模型具有酶和电子载体（醌）之间的扩散耦合反应。脂质不饱和度还调节了工程芽殖酵母菌株的线粒体呼吸。因此，ETC 中的扩散可以作为呼吸膜中脂质成分的进化约束。