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Lipid biosynthesis in eukaryotic cells

studies on enzyme activities involved in fatty acid activation and acylation

Neal, Andrea C. (2006). Lipid biosynthesis in eukaryotic cells. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2006:78
ISBN 91-576-7127-3
[Doctoral thesis]

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Abstract

Lipid molecules are fundamental to cellular function and structure. Lipid metabolic events leading to these basic building blocks has been intensely studied, but are still not fully understood. Through five different studies on enzymes involved in activation and acylation of acyl groups done in three different model organisms we have uncovered novel data on lipid biosynthesis and utilization. Saccharomyces cerevisiae contains two homologous glycerol-3-phosphate acyltransferases, GPT2 and SCT1, which catalyses the first step in the acyl-lipid assembly. Deletion or over expression of the corresponding genes has not only strong effects on the glycerol-3-phsophate activity but also on the total acyl content as well as on lipid and acyl composition. (Paper I) The main form of storage lipids in seeds is Triacylglycerol. The TAZ1 from Saccharomyces cerevisiae, At104.1, and At104.2 from Arabidopsis thaliana are acyltransferase homologous genes that when overexpressed increase oil quantity in Yeast and Plants. (Patent I) Wax esters and ethyl esters are unique constituents that have roles in energy storage and cell structure. In this work we show that microsomal preparations from Arabidopsis thaliana leaves efficiently acylate free fatty acids to long chain alcohols with no activation of the fatty acids to thioesters prior to acylation. We also show that in this enzymatic reaction long chain (C18–C24) unsaturated fatty alcohols and C18–C22 unsaturated fatty acids were preferred. (Paper II) Long-chain acyl-CoA synthetases activate fatty acids and provide substrates for virtually every metabolic pathway that catabolizes FA or synthesizes complex lipids. In Mus musculus heart tissue we show that ACSL1 mRNA levels increase by 2.5 fold after birth, which correlates with the 14 fold increase in total ACSL activity at this time. In contrast,the levels of ACSL3, 4, and 6 mRNA were high in the embryonic heart, and decreased dramatically after birth suggesting that these isoforms may play a critical role during the development of the fetal heart. (Paper III) Microsomes of Saccharomyces cerevisiae and developing Elm (Ulmus glabra) seeds contain a novel type of acyltransferase activity, a acyl-CoA dependent acylation of glycerophosphodiesters. Glycerophosphocholine was acylated by yeast microsomes with a Vmax of 8.7 nmol/min/mg protein and a Km of 2.5 mM. The GPCAT activity was sensitive to NEM, phenantroline and Zn2+ ions. (Paper IV)

Authors/Creators:Neal, Andrea C.
Title:Lipid biosynthesis in eukaryotic cells
Subtitle:studies on enzyme activities involved in fatty acid activation and acylation
Year of publishing :August 2006
Volume:2006:78
Number of Pages:62
Papers/manuscripts:
NumberReferences
ALLPapers I-IV and patent 1 I. Neal, A.C., Banas, A., Ronne, H. & Ståhl, U. Changes in Lipid Composition of Saccharomyces cerevisiae strains with Altered Glycerol-3-Phosphate Acyltransferase Gene Expression. Manuscript II. Neal, A.C., Banas, A., Banas, W., Ståhl, U., Carlsson, A.S. & Stymne, S. 2006. Microsomal preparations from plant and yeast acylate free fatty acids without prior activation to acyl thioesters. Biochim Biophys Acta 1761, 757-764 III. Neal, A.C., Coleman, R.A. & Lewin, T.M. Ontogeny of mRNA expression and activity of long-chain acyl-CoA synthetase (ACSL) isoforms in Mus musculus heart. Manuscript IV. Stålberg, K., Neal, A.C. & Ståhl, U. Glycerophosphodiester Acyltransferase; a New Class of Acylation Activity in Lipid Biosynthesis. Manuscript 1. Cirpus, P., Oswald, O., Ronne, H., Dahlquist, A., Lenman, M., Neal, A.C., Ståhl, U., Liu, T., Banas, A., Wiberg, E. Use of TAZ1 for Increasing Oil Quantity in Plants. International Patent Number: PCT/EP2004/003845 Filed: April 13th 2004
Place of Publication:Uppsala
ISBN for printed version:91-576-7127-3
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:lipids, biosynthesis, enzymes, enzyme activity, esters, fatty acids, acylation, mice, arabidopsis thaliana, saccharomyces cerevisiae
Keywords:glycerol-3-phosphate acyltransferase, tafazzin, long chain acyl-CoA synthetase, wax ester, ethyl ester, triacylglycerol, glycerophosphocholine, glycerophosphoethanolamine, Mus musculus, Arabidopsis thaliana, Saccharomyces cerevisiae
URN:NBN:urn:nbn:se:slu:epsilon-1161
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-1161
ID Code:1173
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: Andrea Neal
Deposited On:29 Aug 2006 00:00
Metadata Last Modified:02 Dec 2014 10:10

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