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.
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- <![endif]>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.
Lipid: ___________________
H
R1
O
C
H
R2
O
C
H
HOH2C
H
C
H
O
O
OH
H
HOH2C
R1
O
C
H
R2
O
C
H
CH2 H
C
H
O
O
O
OH
OH
O
OH
OH
OH
H
HO3S
CH2
R1
O
C
H
R2
O
C
H
C
H
O
O
H
OH
OH
OH
OH
H
H
OH
OH
H
H
H
C
C
C
O
O
H
R1
R2
H
H
OH
O
C
C
O
O
H
R1
R2
O
O
H
C
P
O
H
H
C
C
H
H
+
H
H
P
C
C
H
COOH
O
O
NH2
H
H
C
C
C
O
O
H
R1
R2
H
H
H
C
C
C
O
O
H
R1
R2
H
N(CH3)3
OH
H
H
OH
O
P
O
OH
O
O
P
O
O
H
H
C
C
H
H
H
H
H
C
C
C
H
OH OH
NH2
H
H
R1
O
C
H
R2
O
C
H
H
C
H
OH
O
P
H
OH OH
O
O
H
H
H
C
C
C
O
O
H
R1
R2
OH
O
P
O
O
H
H
H
C
C
C
H
OH O
HO
P
H
H
O
C
C
C
O
O
H
O
OH
OH
OH
H
NH2
CH3
O
FA FA
R
OH
H
O
R
NH
CH3
O
R
OH
Fatty acids:
H
Table 1. Short and medium chain fatty acids.
Formula
(chemical name)
common name
# Carbons
HCOOH
formic acid
1
CH3COOH
acetic acid
2
CH3CH2COOH
proprionic
3
CH3(CH2)2COOH
butyric
4
CH3(CH2)3COOH
(pentanoic)
valeric
5
CH3(CH2)4COOH
(hexanoic)
caproic
6
CH3(CH2)5COOH
heptanoic
7
CH3(CH2)6COOH
(octanoic)
caprylic
8
CH3(CH2)7COOH
nonanoic
9
CH3(CH2)8COOH
(decanoic)
capric
10
CH3(CH2)9COOH
undecanoic
11
CH3(CH2)10COOH
(____________)
lauric
12
CH3(CH2)11COOH
tridecanoic
13
CH3(CH2)12COOH
(____________)
myristic
14
CH3(CH2)13COOH
pentadecanoic
15
Table 2. Important long-chain fatty acids:
(hexadeca-noic)
palmitic
16:0
(cis 7hexadecenoic)
[palmitoleic(D9)]
16:1
7,10hexadecadienoic
16:2
7,10,13hexadecatrienoic
(roughanic)
16:3
(9-octadecenoic)
oleic acid
18:1
(9,12octadecadieno
ic)
linoleic
18:2
(9,12,15octadecatrienoic)
linolenic acid
18:3
(5,8,11,14eicosatetraeno
ic)
arachidonic
20:4 [ ]
(5,8,11,14,17eicosapentaenoic)
timnodonic; EPA
20:5
Heptadeca-noic
17:0
(_____________)
stearic
18:0
Nonadeca-noic
19:0
(eicosanoic)
arachidic
20:0
(docosanoic)
behenic
22:0
(13-docosenoic)
erucic
22:1 [
]
(tetracosa-noic)
lignoceric
24:0
(15-tetracosenoic)
nervonic
24:1
waxes &
cuticular lipids
(4,7,10,13,16,19docosahexaenoic)
cervonic; DHA
22:6
H
H
H
H
C
C
C
O
O
H
R1
R2
-O
CH3
Head Group
or R3
O
-O
CH3
O
-O
CH3
O
CH3
-O
O
-
O
CH3
O
CH3
-O
KAS =
TE =
DS =
AT =
O
What is the source of the acetyl-CoA?
Why is it that the reaction stops at C16 and C18 fatty acids?
Reading Assignment for the second lipid lecture:
a)
REQUIRED:
1 - Engelman, D.M. 2005. Membranes are more mosaic than fluid.
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 282:13151317.
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.
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.