Abstract:
:The esterification of lysophospholipids contributes to phospholipid synthesis, remodeling, and scavenging. Acyl-CoA-dependent lysophospholipid acyltransferase activity with broad substrate use is mediated by Saccharomyces cerevisiae Lpt1p. We sought to identify Lpt1p active site amino acids besides the histidine conserved among homologs and repeatedly found to be required for catalysis. In vitro Lpt1p assays with amino acid modifying agents implicated aspartate, glutamate, and lysine as active site residues. Threonine and tyrosine were not ruled out. Aligning the primary structures of functionally characterized LPT1 homologs from fungi, plants, and animals identified 11 conserved aspartate, glutamate, lysine, threonine, and tyrosine residues. Site-directed mutagenesis of the respective codons showed that changing D146 and E297 abolished activity without abolishing protein expression. The mechanism of Lpt1p was further analyzed using monounsaturated acyl-CoA species with different double bond positions. Delta 6 species showed the highest catalytic efficiency. We propose that D146 and E297 act in conjunction with H382 as nucleophiles that attack the hydroxyl group in lysophospholipids in a general acid/base mechanism. This sequential mechanism provides a precedent for other members of the membrane bound O-acyltransferase family. Also, Lpt1p optimally orients acyl-CoA substrates with 7.5 Å between a double bond and the thioester bond.
journal_name
J Lipid Resjournal_title
Journal of lipid researchauthors
Renauer P,Nasiri N,Oelkers Pdoi
10.1194/jlr.M062141subject
Has Abstractpub_date
2015-11-01 00:00:00pages
2143-50issue
11eissn
0022-2275issn
1539-7262pii
jlr.M062141journal_volume
56pub_type
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pub_type: 杂志文章
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pub_type: 杂志文章
doi:10.1194/jlr.M064709
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journal_title:Journal of lipid research
pub_type: 临床试验,杂志文章,随机对照试验
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pub_type: 杂志文章
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pub_type: 杂志文章
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更新日期:2013-02-01 00:00:00
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pub_type: 杂志文章
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pub_type: 杂志文章
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