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Identification of a novel lysophospholipid acyltransferase in Saccharomyces cerevisiae
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http://hdl.handle.net/1860/2626
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| Title: | Identification of a novel lysophospholipid acyltransferase in Saccharomyces cerevisiae |
| Authors: | Shilpa, Jain
Stanford, NaTaza
Bhagwat, Neha
Seiler, Brian
Costanzo, Michael
Boone, Charles
Oelkers, Peter |
| Issue Date: | 2007 |
| Publisher: | American Society for Biochemistry and Molecular Biology |
| Citation: | Journal of Biological Chemistry, 282(42): pp. 30562-30569. |
| Abstract: | The incorporation of unsaturated acyl
chains into phospholipids during de novo
synthesis is primarily mediated by the 1-acylsn-
glycerol-3-phosphate acyltransferase
reaction. In S. cerevisiae, Slc1 has been shown
to mediate this reaction but distinct activity
remains after its removal from the genome. To
identify the enzyme that mediates the
remaining activity, we performed synthetic
genetic array analysis using a slc1Δ strain. One
of the genes identified by the screen, LPT1, was
found to encode for an acyltransferase that uses
a variety of lysophospholipid species, including
1-acyl-sn-glycerol-3-phosphate. Deletion of
LPT1 had a minimal effect on 1-acyl-snglycerol-
3-phosphate acyltransferase activity
but over-expression increased activity 7-fold.
Deletion of LPT1 abrogated the esterification of
other lysophospholipids and over-expression
increased lysophosphatidylcholine
acyltransferase activity 7-fold. The majority of
this activity co-purified with microsomes. To
test the putative role for this enzyme in
selectively incorporating unsaturated acyl
chains into phospholipids, in vitro, substrate
concentration series experiments were
performed with the four acyl-CoA species
commonly found in yeast. While the saturated
palmitoyl-CoA and stearoyl-CoA showed a
lower apparent Km, the monounsaturated
palmitoleoyl-CoA and oleoyl-CoA showed a
higher apparent Vmax. Arachidonyl-CoA,
although not abundant in yeast, also had a high
apparent Vmax. Pulse-labeling of lpt1Δ strains
showed a 30% reduction in [3H]oleate
incorporation into phosphatidylcholine only.
Therefore, Lpt1p, a member of the membrane
bound o-acyltransferase gene family, seems to
work in conjunction with Slc1 to mediate the incorporation of unsaturated acyl-chains into
the sn-2 position of phospholipids. |
| URI: | http://dx.doi.org/10.1074/jbc.M706326200
http://hdl.handle.net/1860/2626 |
| Appears in Collections: | Faculty Research and Publications (Chemistry)
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