Trafficking of plant vacuolar invertases: from a membrane-anchored to a soluble status. Understanding sorting information in their complex N-terminal motifs.
Vacuolar invertases (VIs) are highly expressed in young tissues and organs. They may have a substantial regulatory influence on whole-plant metabolism as well as on photosynthetic efficiency. Therefore, they are emerging as potentially interesting biotechnological targets to increase plant biomass production, especially under stress. On the one hand, VIs are well known as soluble and extractable proteins. On the other hand, they contain complex N-terminal propeptide (NTPP) regions with a basic region (BR) and a transmembrane domain (TMD). Here we analyzed in depth the Arabidopsis thaliana VI2 (AtVI2) NTPP by mutagenesis. It was found that correct sorting to the lytic vacuole (LV) depends on the presence of intact dileucine (SSDALLPIS), BR (RRRR) and TMD motifs. AtVI2 remains inserted into membranes on its way to the LV, and the classical sorting pathway (endoplasmic reticulum→Golgi→LV) is followed. However, our data suggest that VIs might follow an alternative, adaptor protein 3 (AP3)-dependent route as well. Membrane-anchored transport and a direct recognition of the dileucine motif in the NTPP of VIs might have evolved as a simple and more efficient sorting mechanism as compared with the vacuolar sorting receptor 1/binding protein of 80 kDa (VSR1/BP80)-dependent sorting mechanism followed by those proteins that travel to the vacuole as soluble proteins.
['Xiang|Li|L|', 'Van den Ende|Wim|W|']
D033963:Adaptor Protein Complex 3 D020816:Amino Acid Motifs D000595:Amino Acid Sequence D017360:Arabidopsis D029681:Arabidopsis Proteins D002462:Cell Membrane D004721:Endoplasmic Reticulum D055786:Gene Knockout Techniques D017930:Genes, Reporter D006056:Golgi Apparatus D008954:Models, Biological D008969:Molecular Sequence Data D016297:Mutagenesis, Site-Directed D009154:Mutation D018515:Plant Leaves D030821:Plants, Genetically Modified D017434:Protein Structure, Tertiary D021381:Protein Transport D011993:Recombinant Fusion Proteins D016415:Sequence Alignment D014617:Vacuoles D043324:beta-Fructofuranosidase
Invertase Sorting Arabidopsis thaliana Vacuole BP80 Sucrose