1. Lecture Nineteen Lipids -- Introduction, Synthesis of Fatty Acids, Waxes and Cutin Purpose and Outline The purpose of today's lecture/discussion is introduce some aspects of the biological chemistry of plant glycerolipids you likely didn't study previously. We will also review saturated fatty acid biosynthesis with emphasis on aspects unique to plants. Finally we will briefly cover the synthesis of waxes and cutin in plants. Reading Assignment for the First Lipids Discussion for Class: a) REQUIRED: 1- Gniwotta, F., G. Vogg, V. Gartmann, T.L.W. Carver, M. Riederer, and R. Jetter. 2005. What Do Microbes Encounter at the Plant Surface? Chemical Composition of Pea Leaf Cuticular Waxes. Plant Physiol. 139: 519-530.Plant Physiol. 139: 519-530 2- Kroumova, A.B., Z. Xie and G.J.Wagner. 1994. A pathway for the biosynthesis of straight and branched, odd- and even-length, medium-chain fatty acids in plants. Proc. Natl. Acad. Sci. USA 91: 11437-11441. 3- Chapter 10, pp 456-476, of the Biochemistry & Molecular Biology of Plants class text. b) OPTIONAL: 1- Yu, B. and C. Benning. 2003. Anionic lipids are required for chloroplast structure and function in Arabidopsis. The Plant Journal. 36: 762-770. 2- Sakurai, I., M. Hagio, Z. Gombos, T. Tyystjarvi, V. Paakkarinen, E.- M. Aro and H. Wada. 2003. Requirement of Phosphatidylglycerol for Maintenance of Photosynthetic Machinery. Plant Physiol. 133: 1376-1384. 3- Dehesh, K., H. Tai, P. Edwards, J. Byrne and J.G. Jaworski. 2001. Overexpression of 3-ketoacyl-acyl-carrier protein synthase IIIs in plants reduces the rate of lipid biosynthesis. Plant Physiology 125: 1103-1114. 4- Focks, N. and C. Benning. 1998. wrinkled 1: A novel, low-seed-oil mutant of Arabidopsis with a deficiency in the seed-specific regulation of carbohydrate metabolism. Plant Physiol. 118:91-101. 5- Martinez-Force, E. and R. Garces. 2002. Dynamic channelling during de novo fatty acid biosynthesis in Helianthus annuus seeds. Plant Physiology and Biochemistry 40: 383-391. 6- Ohlrogge, J.B. and J.G. Jaworski. 1997. Regulation of fatty acid synthesis. Annu. Rev. Plant Physiol. Plant Molec. Biol. 48:109-136.

2. Lipid: ___________________

4. Fatty acids:

5. Formula(chemical name) common name # Carbons HCOOHformic acid1 CH 3 COOHacetic acid2 CH 3 CH 2 COOHproprionic3 CH 3 (CH 2 ) 2 COOHbutyric4 CH 3 (CH 2 ) 3 COOH (pentanoic) valeric 5 CH 3 (CH 2 ) 4 COOH (hexanoic) caproic 6 CH 3 (CH 2 ) 5 COOHheptanoic7 CH 3 (CH 2 ) 6 COOH (octanoic) caprylic 8 CH 3 (CH 2 ) 7 COOHnonanoic9 CH 3 (CH 2 ) 8 COOH (decanoic) capric 10 CH 3 (CH 2 ) 9 COOHundecanoic11 CH 3 (CH 2 ) 10 COOH (____________) lauric 12 CH 3 (CH 2 ) 11 COOHtridecanoic13 CH 3 (CH 2 ) 12 COOH (____________) myristic 14 CH 3 (CH 2 ) 13 COOHpentadecanoic15 Table 1. Short and medium chain fatty acids.

6. Table 2. Important long-chain fatty acids: (hexadeca-noic) palmitic 16:0 (cis 7- hexadecenoic) [palmitoleic(  9)] 16:1 7,10- hexadecadie- noic 16:2 7,10,13- hexadecatrienoic (roughanic) 16:3 Heptadeca-noic 17:0 (_____________) stearic 18:0 (9-octadecenoic) oleic acid 18:1 (9,12- octadecadieno ic) linoleic 18:2 (9,12,15- octadecatrienoic) linolenic acid 18:3 Nonadeca-noic 19:0 (eicosanoic) arachidic 20:0 (5,8,11,14- eicosatetraeno ic) arachidonic 20:4 [ ] (5,8,11,14,17- eicosapentaenoic) timnodonic; EPA 20:5 (docosanoic) behenic 22:0 (13-docosenoic) erucic 22:1 [ ] (4,7,10,13,16,19- docosahexaenoic) cervonic; DHA 22:6 (tetracosa-noic) lignoceric 24:0 (15-tetracosenoic) nervonic 24:1 waxes & cuticular lipids

7. KAS = TE = DS = AT =

8. What is the source of the acetyl-CoA?acetyl-CoA

9. Why is it that the reaction stops at C16 and C18 fatty acids?

14. a) REQUIRED: 1 - Engelman, D.M. 2005. Membranes are more mosaic than fluid. Nature 438: 578-580. Nature 438: 578-580 2 - Voelker, T. and A.J. Kinney. 2001. Variations in the Biosynthesis of Seed-Storage Lipids. Annual Review of Plant Physiology and Plant Molecular Biology 52: 335-361. 3 - Chapter 10, sections 10.5 - 10.8 and 10.10.1 -10.10.3, of the Biochemistry & Molecular Biology of Plants class text. b) OPTIONAL: 1 - Broun et al. 1998. Catalytic plasticity of fatty acid modification enzymes underlying chemical diversity of plant lipids. Science 282:1315- 1317. 2 - Shanklin, J. and Cahoon, E.B. 1998. Desaturation and related modifications of fatty acids. Annu. Rev. Plant Physiol. Plant Molec. Biol. 49:611-641. 3 - Beisson, F., A. J. K. Koo, S. Ruuska, J. Schwender, M. Pollard, J. J. Thelen, T. Paddock, J. J. Salas, L. Savage, A. Milcamps, V. B. Mhaske, Y. Cho and J. B. Ohlrogge. 2003. Arabidopsis Genes Involved in Acyl Lipid Metabolism. A 2003 Census of the Candidates, a Study of the Distribution of Expressed Sequence Tags in Organs, and a Web-Based Database. Plant Physiol. 132: 681-697. 4 - McMahon, H.T., and J.L. Gallop. 2005. Membrane curvature and mechanisms of dynamic cell membrane remodelling. Nature 438:590-596.Nature 438:590-596 5 - Murakami et al. 2000. Trienoic fatty acids and plant tolerance of high temperature. Science 287:477-479. 6 - Dahlqvist, A., U. Stahl, M. Lenman, A. Banas, M. Lee, L. Sandager, H. Ronne and S. Stymne. 2000. Phospholipid:diacylglycerol acyltransferase: An enzyme that catalyzes the acyl-CoA-independent formation of triacylglycerol in yeast and plants. Proc. Natl. Acad. Sci. USA 97: 6487-6492. Reading Assignment for the second lipid lecture: