Why discuss the topic of: lipid Biosynthesis? Lipids as: - Biofuels. Dehesh UC Davis

Transcription

1 Why discuss the topic of: lipid Biosynthesis? Lipids as: - Biofuels Dehesh UC Davis

2 Fossil fuel is believed to be derived from ancient lipid rich organic material such as spores and planktonic algae!

3 Rudolf Diesel used peanut oil as liquid fuels in internal combustion engines (1900) Because of its low cost and easy availability, petroleum became the dominant energy source and petroleum diesel was then developed as the primary fuel for diesel engines Petroleum and its derivatives fuels were in short supply in 1930 and hence in the 1930s and 1940s, neat vegetable oils were used in diesel engines under an emergency situation (Ma and M.A. Hanna, Biodiesel production: a review, Bioresource Technology 70 :1 15. ) During this period two approaches were used: 1- Hydrocarbons were produced in China by a Tung oil pyrolysis batch system and used as liquid fuels 2- Fatty acids ethyl or methyl esters, obtained by transesterification or alcoholysis of vegetable oils alcoholysis /al co hol y sis/ (al kah-hol ĭ-sis) decomposition of a compound due to the incorporation and splitting of alcohol

4 Why discuss the topic of: lipid Biosynthesis? Lipids as: - Biofuels - protective agents

5 C- Cuticular lipids are protective agents Found in surface of all terrestrial plants. Crucial hydrophobic barrier to prevent H 2 O loss & protection against pathogens & other environmental stresses. Contain: 1- Cutin: polymer of carbon hydroxyl fatty acids cross linked by esterification of their carboxyl groups to hydroxyl groups of neighboring acylchain. 2- Wax esters: a mixture of long-chain fatty acids, and fatty alcohols and esters.

6 Why discuss the topic of: lipid Biosynthesis? Lipids as: - Biofuels - protective agents - Signaling compounds

7 Fatty acids as signaling molecules Plants OXYLIPINS Animals LIPASE arachidonic acid 20:4 COXs LOXs CYP450

8 Why discuss the topic of: lipid Biosynthesis? Lipids as: - Biofuels - protective agents - Signaling compounds - Pharmaceutical

9 Fatty Acids and Health Lorenzo s oil ( a blend of trierucin/triolein) A cure to adrenoleukodystrophy (ADL), an X-linked disorder

10 Lipid Biosynthesis

11 A. Major Class: Classes of Lipids The most abundant type are derived from fatty acid and glycerolipid biosynthetic pathway. B. Minor Class: Derived from isoprenoid pathway and there are over isoprenoid compounds. Mostly are "Secondary metabolites" not found in all cells (not essential to growth). Sterols, gibberellins, abscisic acid + phytol side chain of chlorophyll are from this pathway. The Fatty Acid biosynthesis is a Primary Metabolic Pathway: in all cells, essential for growth. No mutation or inhibitors : lethal.

12 Lipid Biosynthesis A: membrane B: Carbon Storage C- Cuticular lipids

13 In plants plastids are the predominant site of FA biosynthesis Fatty acids in animals and fungi are produce in the cytosol

14 Major fatty acids in plants Fatty acids in plants, and most other organisms have a chain length of 16 or 18 carbons, and contain one to three cis double bonds. Five major fatty acids: 16:0 16:3, make up over 90% of the acyl-chains of the structural glycerolipids of all plant membranes 18:1 18:2 18:3 ** Never as Free Fatty acids in cells, instead, their carboxyl group is esterified or otherwise modified. They are esterified to glycerols glycerolipids

15 Lipid Biosynthesis 18:1-ACP 18:1 R-CoA PLASTID 4:0-ACP Acetyl-CoA ACP 12:0-ACP 14:0-ACP 18:0-ACP 16:0-ACP P RRP-Choline P MEMBRANE LIPIDS OILBODY CYTOPLASM CPT R R R R R P R R R ACP 18:0 16:0 Malonyl-CoA CO CO 2 2 TAG DAGAT GPAT LPAAT PAP ACCase KASIII THIOESTERASE 9-DESATURASE 6:0-ACP 8:0-ACP 10:0-ACP KASI KASII

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17 Lipid Biosynthesis 18:1-ACP 18:1 R-CoA PLASTID 4:0-ACP Acetyl-CoA ACP 12:0-ACP 14:0-ACP 18:0-ACP 16:0-ACP P RRP-Choline P MEMBRANE LIPIDS OILBODY CYTOPLASM CPT R R R R R P R R R ACP 18:0 16:0 Malonyl-CoA CO CO 2 2 TAG DAGAT GPAT LPAAT PAP ACCase KASIII THIOESTERASE 9-DESATURASE 6:0-ACP 8:0-ACP 10:0-ACP KASI KASII

18 Membrane Essential Constituent, of all cells: Vegetative cells of plant contain 5-10% lipid by dry weight, mostly found in membranes Delineate the cell & its compartment Site of essential processes such as light harvesting & electron transport of photosynthesis Membrane glycerolipids have fatty acids attached to both the Sn-1 and Sn-2 position of glycerol backbone. Polar headgroup attached to Sn-3 position.

19 Membrane Fatty Acids Combination of polar and nonpolar -> amphipathic property of glycerolipids -> an essential property for the formation of membrane bilayer. glycerophospholipid has: 1- A polar region: glycerol, carbonyl oxygens of fatty acids, phosphate, and the polar head group. 2- Two nonpolar hydrocarbon tails of fatty acids.

20 Structures of the major fatty acids and glycerolipids of plant cell membrane

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23 Mutants plants with altered FA composition

24 Membrane composition and cold tolerance

25 Distribution of lipid classes

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27 B: Carbon Storage: Plant use reduced carbon derived from photosynthesis to store energy. Main forms of reserves are Carbohydrates, protein & oils. Oils most efficient form of energy storage carbons in Fatty acids are highly reduced (more than carbohydrates), and therefore oxidation of oils release twice as much energy as the oxidation of carbohydrates or proteins. Many seeds synthesize oil in developing seeds to act as energy source in germination. In some species up to 60% of seed dry weight is oil.

28 Lipid Biosynthesis 18:1-ACP 18:1 R-CoA PLASTID 4:0-ACP Acetyl-CoA ACP 12:0-ACP 14:0-ACP 18:0-ACP 16:0-ACP P RRP-Choline P MEMBRANE LIPIDS OILBODY CYTOPLASM CPT R R R R R P R R R ACP 18:0 16:0 Malonyl-CoA CO CO 2 2 TAG DAGAT GPAT LPAAT PAP ACCase KASIII THIOESTERASE 9-DESATURASE 6:0-ACP 8:0-ACP 10:0-ACP KASI KASII

29 B- Plant oil as an alternative source of biofuel: Three positions of glycerol esterified with Fatty acid -> triacylglycerol (TAG) -> major form of lipids in TAG: Sn-2 Sn-1 Plants: mono and polyunsaturated 18carbons Sn-3 Animals: Saturated TAGS Plant TAGs: Plant storage lipids are important components of human and animal diets. Industrial use: detergents, paints, lubricants. Loosely defined as H 2 O insoluble compounds- extractable by organic solvent such as chloroform.

30 C18:1-ACP Fatty Acids in Common Vegetable Oils acetyl-coa C4:0-ACP C6:0-ACP C8:00-ACP C10:0-ACP C12:0-ACP Soybean Cotton Canola Safflower Sunflower Maize Flax Sesame C14:0-ACP C16:0-ACP C18:0-ACP C16:0 C18:0 C18:0 [C18:2, C18:3]

31 Diversity in structure and hence application of lipids

32 C- Cuticular lipids are protective agents Found in surface of all terrestrial plants. Crucial hydrophobic barrier to prevent H 2 O loss & protection against pathogens & other environmental stresses. Contain: 1- Cutin: polymer of carbon hydroxyl fatty acids cross linked by esterification of their carboxyl groups to hydroxyl groups of neighboring acylchain. 2- Wax esters: a mixture of long-chain fatty acids, and fatty alcohols and esters.

33 Fatty acids as signaling molecules Plants OXYLIPINS Animals LIPASE arachidonic acid 20:4 COXs LOXs CYP450

34 Fatty acids as signaling molecules Minor amount of fatty acid are precursors to hormone & Jasmonic acid (a component of signal transduction pathway)

35 JA protects plants from insects Fatty acids as signaling molecules Jasmonic acid (a component of signal transduction pathway) JA is a plant growth regulator derived form 18:3, and is capable of induction of plant defense genes, at low concentrations. Biosynthesis and structure of jasmonate is very similar to that of eicosanoids that are central to inflammatory responses in mammals.

36 Fatty acids as signaling molecules Plants OXYLIPINS Animals LIPASE arachidonic acid 20:4 COXs LOXs CYP450

37 AA treatment enhances resistance to Botrytis Mock AA Lesion diameter (cm) P = <0.001 Mock AA

38 AA enhanced resistance to Botrytis is mediated via JA pathway JA (ng/g FW)800 Mock AA 0 Mock AA

39 Biotic and abiotic stress signals PLD LOX2 AOS AOC OPR3 JA VSP2

40 AA induces JA levels in tomato 4 3 JA, ng/g fw Mock 18:2 18:3 20:2 20:3 AA

41 P = Lesion area (cm 2 ) Mock AA Mock AA Mock AA JA (ng/g f.w.)

42 RSRE response to Botrytis infection

43 Multimerized RSREs are sufficient to confer rapid responses to both biotic and abiotic stresses in vivo RSRE = ATAACGCGTTTTTA 4X RSRE LUCIFERASE THUS RSRE is a functional motif involved in primary stress responses

44 Rapid Stress Response Element (RSRE) RSRE = ATAACGCGTTTTTA 4X RSRE LUCIFERASE 1600 Bioluminescence W 4xRSRE Wounded Leaf 4xRSRE Systemic Leaf Background Vector Control Wounded Leaf Time (min) Walley et al., PLoS Gent 07

45 AA elicits expression of 4XRSRE:LUC

46 AA elicits expression of 4XRSRE:LUC 200 Bioluminescence Time (min) AA Mock 350

47 Fatty acids and disease Lorenzo s oil ( a blend of trierucin/triolein) A cure to adrenoleukodystrophy (ADL), an X-linked disorder

48 Fatty acids and disease Science 1998 Jun 5;280(5369): Inhibition of a Mycobacterium tuberculosis beta-ketoacyl ACP synthase by Isoniazid Nutrition 2000 Mar;16(3):202-8 Fatty-acid synthase and human cancer: new perspectives on its role in tumor biology Science 2000 Apr 7;288(5463):140-3 Specialized fatty acid synthesis in African trypanosomes: myristate for GPI anchors.

49 acetyl-coa C4:0-ACP Medium Chain Fatty Acids C6:0-ACP C8:00-ACP C10:0-ACP C12:0-ACP C8:0 C10:0 acyl-coas C14:0-ACP C16:0-ACP Structural lipids Storage lipids C18:0-ACP C18:1-ACP chloroplast/proplastid Free fatty acids {further desaturation} endoplasmic reticilum

50 MCTs and their application Comprised primarily of caprylic (8:0) and capric (10:0) Application: A: Food Full and Pre-term infant formula Athletic supplements B: Nutrition/Pharmaceutical Oral, enteral and IV nutrition: Digested, and absorbed and transported rapidly Dietetic/low calorie food: Oxidized rapidly in the organism and hence low tendency to deposit as body fat Ketogenic, a diet traditionally given to drug resistance children with epilepsy to improve seizure control Controlling diarrhea and fat malabsorption in HIV-positive patients Potentially, as part of ketogenic diet in slowing tumor growth C: Industrial Biogradable lubricants and Biodiesel