Fig. 1

Design of GPAT-expression constructs for N. oceanica. Schematic of the ER-localized N. oceanica GPAT isoform NO03G04130 (NoGPAT) and the A. obliquus chloroplastic GPAT (AoGPAT) are shown together with a simplified schematic of the expression construct (not drawn to scale). Putative orientations of the different NoGPAT regions are indicated by ER or C for ER-lumenal and cytoplasmic orientation, respectively. Both genes were equipped with a C-terminal coding sequence for an HA tag, to allow immunodetection of proteins. Artificially added elements are colored yellow. GPAT genes were inserted into an expression construct based on a recently developed expression system [35], containing a Pol I promoter and terminator, an internal ribosome entry site (IRES) and an expression enhancer (T \({}_{\mathrm{\alpha }-\mathrm{tub}}\)). A fluorescent reporter (tdTomato) and antibiotic resistance gene (zeo \({}^{R}\)) were added for expression quantification and selection, respectively. The three genes were separated by coding sequences for self-cleaving 2A peptides to allow expression as a single cistron