Lipids Structure And Function Pdf

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Lipids Structure & Functions

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Previous studies have established that the folding, structure and function of membrane proteins are influenced by their lipid environments 1 , 2 , 3 , 4 , 5 , 6 , 7 and that lipids can bind to specific sites, for example, in potassium channels 8.

Fundamental questions remain however regarding the extent of membrane protein selectivity towards lipids. Here we report a mass spectrometry approach designed to determine the selectivity of lipid binding to membrane protein complexes. We investigate the mechanosensitive channel of large conductance MscL from Mycobacterium tuberculosis and aquaporin Z AqpZ and the ammonia channel AmtB from Escherichia coli , using ion mobility mass spectrometry IM-MS , which reports gas-phase collision cross-sections.

We demonstrate that folded conformations of membrane protein complexes can exist in the gas phase. By resolving lipid-bound states, we then rank bound lipids on the basis of their ability to resist gas phase unfolding and thereby stabilize membrane protein structure. Lipids bind non-selectively and with high avidity to MscL, all imparting comparable stability; however, the highest-ranking lipid is phosphatidylinositol phosphate, in line with its proposed functional role in mechanosensation 9.

AqpZ is also stabilized by many lipids, with cardiolipin imparting the most significant resistance to unfolding. Subsequently, through functional assays we show that cardiolipin modulates AqpZ function. Similar experiments identify AmtB as being highly selective for phosphatidylglycerol, prompting us to obtain an X-ray structure in this lipid membrane-like environment. The 2. We anticipate that these findings will be important not only for defining the selectivity of membrane proteins towards lipids, but also for understanding the role of lipids in modulating protein function or drug binding.

Singer, S. The fluid mosaic model of the structure of cell membranes. Science , — Cantor, R. The influence of membrane lateral pressures on simple geometric models of protein conformational equilibria. Lipids , 45—56 Hunte, C. Lipids and membrane protein structures. Lee, A. Biological membranes: the importance of molecular detail. Trends Biochem. Sanders, C. Tolerance to changes in membrane lipid composition as a selected trait of membrane proteins. Biochemistry 50 , — Contreras, F.

Specificity of intramembrane protein—lipid interactions. Cold Spring Harb. Whitelegge, J. Integral membrane proteins and bilayer proteomics. Long, S. Nature , — Zhong, D. Phosphatidylinositol is crucial for the mechanosensitivity of Mycobacterium tuberculosis MscL.

Biochemistry 52 , — Chang, G. Structure of the MscL homolog from Mycobacterium tuberculosis : a gated mechanosensitive ion channel. Haswell, E. Mechanosensitive channels: what can they do and how do they do it?

Structure 19 , — Savage, D. Architecture and selectivity in aquaporins: 2. PLoS Biol. Gonen, T. Lipid—protein interactions in double-layered two-dimensional AQP0 crystals. Khademi, S. Barrera, N. Micelles protect membrane complexes from solution to vacuum. Laganowsky, A. Mass spectrometry of intact membrane protein complexes. Nature Protocols 8 , — Ruotolo, B. Evidence for macromolecular protein rings in the absence of bulk water.

Baldwin, A. Hyung, S. Gas-phase unfolding and disassembly reveals stability differences in ligand-bound multiprotein complexes. Pace, C. Determination and analysis of urea and guanidine hydrochloride denaturation curves. Methods Enzymol. Hong, H. Johnson, Jo M. Ackers — Academic Press, Google Scholar. Powl, A. Lipid-protein interactions studied by introduction of a tryptophan residue: the mechanosensitive channel MscL. Biochemistry 42 , — Borgnia, M.

Functional reconstitution and characterization of AqpZ, the E. Tan, B. Discovery of a cardiolipin synthase utilizing phosphatidylethanolamine and phosphatidylglycerol as substrates. Natl Acad. USA , — Yau, W. The preference of tryptophan for membrane interfaces. Biochemistry 37 , — Iscla, I. Sensing and responding to membrane tension: the bacterial MscL channel as a model system. Hite, R. Principles of membrane protein interactions with annular lipids deduced from aquaporin-0 2D crystals.

EMBO J. Romantsov, T. Blakey, D. Purification of the Escherichia coli ammonium transporter AmtB reveals a trimeric stoichiometry. Engelman, D. Membranes are more mosaic than fluid. Gandhi, C. Protein Sci. Hilf, R. X-ray structure of a prokaryotic pentameric ligand-gated ion channel. Lee, D. Gene doctoring: a method for recombineering in laboratory and pathogenic Escherichia coli strains. BMC Microbiol. Drew, D. Optimization of membrane protein overexpression and purification using GFP fusions.

The Metabolism, Structure, and Function of Plant Lipids

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Lipid , any of a diverse group of organic compounds including fats , oils , hormones , and certain components of membranes that are grouped together because they do not interact appreciably with water. One type of lipid, the triglycerides , is sequestered as fat in adipose cells , which serve as the energy-storage depot for organisms and also provide thermal insulation. Some lipids such as steroid hormones serve as chemical messengers between cells , tissues , and organs , and others communicate signals between biochemical systems within a single cell. The membranes of cells and organelles structures within cells are microscopically thin structures formed from two layers of phospholipid molecules. Membranes function to separate individual cells from their environments and to compartmentalize the cell interior into structures that carry out special functions. So important is this compartmentalizing function that membranes, and the lipids that form them, must have been essential to the origin of life itself.

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cholesterol, lipid oxidation and antioxidants; COX activity & COX-1 and COX-2 inhibitors. • The chemistry of lipids is all about how structure affects function. This.


The Biology of Lipids

Hundreds of different lipid species are present in eukaryotic cell membranes. Some of them aggregate with specific membrane proteins to form specialized domains that concentrate and control cellular trafficking and signaling events. For both naked and enveloped viruses, viral entry, genome replication, and egress involve specific interactions with the membranes of a susceptible host cell.

Membrane lipids are a group of compounds structurally similar to fats and oils which form the double-layered surface of all cells lipid bilayer. The three major classes of membrane lipids are phospholipids , glycolipids , and cholesterol. Lipids are amphiphilic: they have one end that is soluble in water 'polar' and an ending that is soluble in fat 'nonpolar'. By forming a double layer with the polar ends pointing outwards and the nonpolar ends pointing inwards membrane lipids can form a 'lipid bilayer' which keeps the watery interior of the cell separate from the watery exterior.

Lipids are a diverse group of molecules that all share the characteristic that at least a portion of them is hydrophobic. Other, amphipathic lipids, such as glycerophospholipids and sphingolipids spontaneously organize themselves into lipid bilayers when placed in water. Interestingly, major parts of many lipids can be derived from acetyl-CoA. Figure 2. The most ubiquitous lipids in cells are the fatty acids.

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    The Biochemistry of Plants: A Comprehensive Treatise, Volume 4: Lipids: Structure and Function provides information pertinent to the fundamental aspects of plant lipid biochemistry.

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