The influence of bacterial lipid composition variation on transporter function and folding.

细菌脂质组成变化对转运蛋白功能和折叠的影响。

• 批准号: RGPIN-2016-05891
• 负责人: Bay, Denice
• 金额: $ 2.77万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615968
• 关键词: influence; bacterial; lipid; composition; variation

Bacterial species diversity is vast and the wide variety and distribution of lipids that reside in their membranes highlights this diversity. Lipids are hydrophobic chemicals that can vary in chain length, saturation, branching and head group charge; all of which result in changes in membrane thickness, net charge and fluidity. Lipid variation has can also be used as a way to classify and distinguish bacterial species from one another. Despite this knowledge, our understanding of how lipids influence the function of bacterial membranes remains poorly understood. A broad assortment of membrane proteins must function within diverse lipid membranes to perform essential functions for the cell. Membrane proteins such as transporters facilitate the movement of substances across these lipid barriers. How transporters fold and function in membranes composed of different lipid compositions is not well understood. The long-term objective of my research program is to examine the influence of bacterial lipid composition on transporter function and folding. To accomplish this, three short-term objectives will focus on the function of multi-ligand transporters found in the membranes of Gram-negative Escherichia coli and of Gram-positive Bacillus subtilis. Lipids that make up each species membrane differ significantly in fatty acid type, bilayer thickness and net charge. The unique differences of each species membrane are ideal to compare transporter function and folding in different lipid compositions by monitoring losses and gains in substrate transport that alter overall cell growth. Objective 1: Involves a comparison of natural lipid variation in E. coli and B. subtilis grown at different temperatures, pH and salinity; conditions which are known to alter lipid content and potentially regulate transporter folding and function. Objective 2: Develops an expression system in each species to deliberately vary the content of specific lipids and transporters by heterologous co-expression of particular lipid biosynthetic and transporter genes. The consequences of lipid variation will be monitored in vivo by observing changes in transporter folding and topology in bacterial membranes. Objective 3: Bioinformatic and statistical comparison of bacterial lipid compositions will be made with transporter protein sequence data to determine how lipid compositions influence amino acid conservation and evolution of regions that face lipids. The significance and impact of this program will provide insights into how lipids potentially regulate membrane protein activity and how growth conditions influence lipid content. Knowledge of how membrane proteins fold and function in diverse lipid environments not only furthers our fundamental knowledge of how these proteins work, but identifies better ways to bioengineer and isolate membrane proteins for industrial and academic applications.

细菌种类的多样性是巨大的，而存在于其膜中的脂质的多样性和分布突出了这种多样性。脂类是疏水化学物质，可以在链长、饱和度、分支和头基电荷等方面发生变化；所有这些都会导致膜厚度、净电荷和流动性的变化。脂质变化也可以作为一种分类和区分细菌种类的方法。尽管有这些知识，我们对脂质如何影响细菌膜功能的理解仍然知之甚少。