title: A mutation in the LPAT1 gene suppresses the sensitivity of fab1 plants to low temperature.
abstract: The Arabidopsis (Arabidopsis thaliana) fatty acid biosynthesis1 (fab1) mutant grows as well as wild type at 22 degrees C, but after transfer to 2 degrees C fab1 plants cannot maintain photosynthetic function and die after 5 to 7 weeks at 2 degrees C. A fab1 suppressor line, S7, was isolated in a screen that identified mutants that remained alive after 16 weeks at 2 degrees C and were able to flower and produce seed after return to 22 degrees C. Relative to wild type, S7 plants had reduced levels of 16:3 fatty acid in leaf galactolipids, indicating reduced synthesis of chloroplast glycerolipids by the prokaryotic pathway of lipid metabolism. The suppressor mutation was identified, by map-based and candidate-gene approaches, as a hypomorphic allele of lysophosphatidic acid acyltransferase1 (lpat1), lpat1-3. LPAT1 encodes the enzyme that catalyzes the second reaction in the prokaryotic pathway. Several lines of evidence indicate that damage and death of fab1 plants at 2 degrees C may be a result of the increased proportion of phosphatidylglycerol (PG) in fab1 that are high-melting-point molecular species (containing only 16:0, 18:0, and 16:1,Delta3-trans fatty acids). Consistent with this proposal, the lpat1-3 mutation strongly affects the fatty acid composition of PG. The proportion of high-melting-point molecular species in PG is reduced from 48.2% in fab1 to 10.7% in fab1 lpat1-3 (S7), a value close to the 7.6% found in wild type.
authors.affiliation: Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340, USA.
authors.forename: Hyun Uk
authors.initials: HU
authors.lastname: Kim
authors.forename: Perumal
authors.initials: P
authors.lastname: Vijayan
authors.forename: Anders S
authors.initials: AS
authors.lastname: Carlsson
authors.forename: Lenore
authors.initials: L
authors.lastname: Barkan
authors.forename: John
authors.initials: J
authors.lastname: Browse
mesh_terms: D051103:1-Acylglycerol-3-Phosphate O-Acyltransferase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology; D003080:Cold Temperature; D018076:DNA, Complementary / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics*; D005816:Genetic Complementation Test; D050356:Lipid Metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D018515:Plant Leaves / Q000378:metabolism; D016415:Sequence Alignment; D013489:Suppression, Genetic
chemical_list: D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D051103:1-Acylglycerol-3-Phosphate O-Acyltransferase