Sunflower HaGPAT9-1 is the predominant GPAT during seed development

• Autor(a) principal: Paya-Milans, Miriam
• Data de Publicação: 2016
• Outros Autores: Antonio Aznar-Moreno, Jose, Balbuena, Tiago S. [UNESP], Haslam, Richard P., Gidda, Satinder K., Perez-Hormaeche, Javier, Mullen, Robert T., Thelen, Jay J., Napier, Johnathan A., Salas, Joaquin J., Garces, Rafael, Martinez-Force, Enrique, Venegas-Caleron, Monica
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.plantsci.2016.07.002; http://hdl.handle.net/11449/162100
• topic: Endoplasmic reticulum; Glycerol-3-phosphate acyltransferase; Helianthus annuus; Mass spectrometry; Triacylglycerol; Yeast

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.