Artículos de revistas
Sunflower HaGPAT9-1 is the predominant GPAT during seed development
Fecha
2016-11-01Registro en:
Plant Science. Clare: Elsevier Ireland Ltd, v. 252, p. 42-52, 2016.
0168-9452
10.1016/j.plantsci.2016.07.002
WOS:000386410000005
WOS000386410000005.pdf
Autor
CSIC
Univ Tennessee
Kansas State Univ
Univ Missouri
Universidade Estadual Paulista (Unesp)
Rothamsted Res
Univ Guelph
Institución
Resumen
In oil crops, triacylglycerol biosynthesis is an important metabolic pathway in which glycerol-3-phosphate acyltransferase (GPAT) performs the first acylation step. Mass spectrometry analysis of developing sunflower (Helianthus annuus) seed membrane fractions identified an abundant GPAT, HaGPAT9 isoform 1, with a N-terminal peptide that possessed two phosphorylated residues with possible regulatory function. HaGPAT9-1 belongs to a broad eukaryotic GPAT family, similar to mammalian GPAT3, and it represents one of the two sunflower GPAT9 isoforms, sharing 90% identity with HaGPAT9-2. Both sunflower genes are expressed during seed development and in vegetative tissues, with HaGPAT9-1 transcripts accumulating at relatively higher levels than those for HaGPAT9-2. Green fluorescent protein tagging of HaGPAT9-1 confirmed its subcellular accumulation in the endoplasmic reticulum. Despite their overall sequence similarities, the two sunflower isoforms displayed significant differences in their enzymatic activities. For instance, HaGPAT9-1 possesses in vivo GPAT activity that rescues the lethal phenotype of the cmy228 yeast strain, while in vitro assays revealed a preference of HaGPAT9-1 for palmitoyl-, oleoyl- and linoleoyl-CoAs of one order of magnitude, with the highest increase in yield for oleoyl- and linoleoyl-CoAs. By contrast, no enzymatic activity could be detected for HaGPAT9-2, even though its over-expression modified the TAG profile of yeast. (C) 2016 Elsevier Ireland Ltd. All rights reserved.