ABA, porphyrins and plant TSPO-related protein.
We have shown that, unexpectedly, AtTSPO (Arabidopsis thaliana TSPO-related protein) is an endoplasmic reticulum and Golgi-localized membrane protein in plant cells.(1) This localization contrasts with that of mammalian 18-kDa translocator protein (at least for the mostly studied isoform, 18-kDa TSPO), a mitochondrial outer membrane protein (reviewed in ref. 2). Whereas the potential functions of 18-kDa TSPO are well documented, involved mainly in mitochondrial physiology,(2) and its interest as drugs target is been explored,(3) the roles of TSPO-related proteins in plant growth and development are yet to be specified. AtTSPO is expressed in dry seeds and can be induced in vegetative tissues by osmotic and salt stress or abscisic acid (ABA) treatment. Moreover, it was shown that the ABA-dependent induction is transient, and that boosting tetrapyrroles biosynthesis through 5-aminolevulinic acid (ALA) feeding enhanced downregulation of AtTSPO, suggesting an inherent post-translational regulation mechanism also involving ABA and likely porphyrins. We present additional evidence that ABA can help stabilize constitutively expressed AtTSPO and that ALA feeding to knockout mutant seeds, induces substantial germination delay. Here we discuss the possible link between ABA and tetrapyrroles in AtTSPO expression and post-translational regulation.
Guillaumot
Damien
D
Institut des Sciences de la Vie, Molecular Physiology Group (FYMO), Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
Guillon
Stéphanie
S
Morsomme
Pierre
P
Batoko
Henri
H
D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D000222:Adaptation, Physiological / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D018525:Germination; D007982:Levulinic Acids / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011166:Porphyrins / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D045725:Tetrapyrroles / Q000096:biosynthesis*
D029681:Arabidopsis Proteins; D007982:Levulinic Acids; D008565:Membrane Proteins; D011166:Porphyrins; C550345:TSPO-related protein, Arabidopsis; D045725:Tetrapyrroles; D000040:Abscisic Acid; C032246:levulinic acid