HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 280, Issue 41, 34626-34634, October 14, 2005

This Article Full Text Full Text (PDF) All Versions of this Article: 280/41/34626    most recent M504459200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Banas, A. Articles by Stymne, S. Search for Related Content PubMed PubMed Citation Articles by Banas, A. Articles by Stymne, S. Social Bookmarking                      What's this?

Cellular Sterol Ester Synthesis in Plants Is Performed by an Enzyme (Phospholipid:Sterol Acyltransferase) Different from the Yeast and Mammalian Acyl-CoA:Sterol Acyltransferases^*

Antoni Bana, Anders S. Carlsson1, Bangquan Huang, Marit Lenman¶, Walentyna Bana||, Michael Lee¶, Alexandre Noiriel**, Pierre Benveniste**, Hubert Schaller**, Pierrette Bouvier-Navé**, and Sten Stymne

From the Department of Crop Science, Swedish University of Agricultural Sciences, P. O. Box 44, SE-230 53 Alnarp, Sweden, College of Life Science, Hubei University, 430062 Wuhan, China, ^¶ScanBi AB, P. O. Box 166, 230 52Alnarp, Sweden, ^||Institute of Biology, University of Podlasie, 08-110 Siedlce, Poland, and the ^**Institut de Biologie Moléculaire des Plantes du CNRS, Département Isoprénoïdes, Institut de Botanique, 28 Rue Goethe, 67083 Strasbourg Cedex, France

A gene encoding a sterol ester-synthesizing enzyme was identified in Arabidopsis. The cDNA of the Arabidopsis gene At1g04010 (AtPSAT) was overexpressed in Arabidopsis behind the cauliflower mosaic virus 35S promoter. Microsomal membranes from the leaves of overexpresser lines catalyzed the transacylation of acyl groups from phosphatidylethanolamine to sterols. This activity correlated with the expression level of the AtPSAT gene, thus demonstrating that this gene encodes a phospholipid:sterol acyltransferase (PSAT). Properties of the AtPSAT were examined in microsomal fractions from the tissues of an overexpresser. The enzyme did not utilize neutral lipids, had the highest activity with phosphatidylethanolamine, had a 5-fold preference for the sn-2 position, and utilized both saturated and unsaturated fatty acids. Various sterols and sterol intermediates, including triterpenic precursors, were acylated by the PSAT, whereas other triterpenes were not. Sterol selectivity studies showed that the enzyme is activated by end product sterols and that sterol intermediates are preferentially acylated by the activated enzyme. This indicates that PSAT both regulates the pool of free sterols as well as limits the amount of free sterol intermediates in the membranes. Two T-DNA insertion mutants in the AtPSAT gene, with strongly reduced (but still measurable) levels of sterol esters in their tissues, had no detectable PSAT activity in the microsomal fractions, suggesting that Arabidopsis possess other enzyme(s) capable of acylating sterols. The AtPSAT is the only intracellular enzyme found so far that catalyzes an acyl-CoA-independent sterol ester formation. Thus, PSAT has a similar physiological function in plant cells as the unrelated acyl-CoA:sterol acyltransferase has in animal cells.

Received for publication, April 25, 2005 , and in revised form, July 8, 2005.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank^TM/EBI Data Bank with accession number(s) AY989885.

^* This work was supported by the Swedish University of Agricultural Sciences strategic research grants, The Biological Factory, Stiftelsen Svensk Oljeväxtforskning, Einar and Inga Nilssons Foundation, and the Swedish Research Council for Environment, Agricultural Sciences, and Spatial Planning (Formas). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Dept. of Crop Science, Swedish University of Agricultural Sciences, P. O. Box 44, SE-230 53 Alnarp, Sweden. Tel.: 46-40415561; Fax: 46-40415519; E-mail: anders.carlsson{at}vv.slu.se.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				Q. Chen, L. Steinhauer, J. Hammerlindl, W. Keller, and J. Zou Biosynthesis of Phytosterol Esters: Identification of a Sterol O-Acyltransferase in Arabidopsis Plant Physiology, November 1, 2007; 145(3): 974 - 984. [Abstract] [Full Text] [PDF]