A TSPO-related protein localizes to the early secretory pathway in Arabidopsis, but is targeted to mitochondria when expressed in yeast
| Autor: | Magali Deleu, Stéphanie Guillon, Celine Vanhee, Danièle Masquelier, Pierre Morsomme, Henri Batoko, Hervé Degand |
|---|---|
| Přispěvatelé: | UCL - SST/ISV - Institut des sciences de la vie |
| Rok vydání: | 2010 |
| Předmět: |
Physiology
Immunoprecipitation Arabidopsis Gene Expression Saccharomyces cerevisiae Plant Science yeast Endoplasmic Reticulum symbols.namesake Translocator protein membrane protein Secretory pathway Secretory Pathway biology Arabidopsis Proteins Endoplasmic reticulum Membrane Proteins Golgi apparatus Abiotic stress Subcellular localization Research Papers Mitochondria Transport protein Cell biology Protein Transport Membrane protein Biochemistry symbols biology.protein sorting TSPO trans-Golgi Network |
| Zdroj: | Journal of experimental botany, Vol. 62, no. 2, p. 497-508 (2011) Journal of Experimental Botany |
| ISSN: | 1460-2431 0022-0957 |
| DOI: | 10.1093/jxb/erq283 |
| Popis: | AtTSPO is a TspO/MBR domain-protein potentially involved in multiple stress regulation in Arabidopsis. As in most angiosperms, AtTSPO is encoded by a single, intronless gene. Expression of AtTSPO is tightly regulated both at the transcriptional and post-translational levels. It has been shown previously that overexpression of AtTSPO in plant cell can be detrimental, and the protein was detected in the endoplasmic reticulum (ER) and Golgi stacks, contrasting with previous findings and suggesting a mitochondrial subcellular localization for this protein. To ascertain these findings, immunocytochemistry and ABA induction were used to demonstrate that, in plant cells, physiological levels of AtTSPO colocalized with AtArf1, a mainly Golgi-localized protein in plant cells. In addition, fluorescent protein-tagged AtTSPO was targeted to the secretory pathway and did not colocalize with MitoTracker-labelled mitochondria. These results suggest that the polytopic membrane protein AtTSPO is cotranslationally targeted to the ER in plant cells and accumulates in the Trans-Golgi Network. Heterologous expression of AtTSPO in Saccharomyces cerevisiae, yeast devoid of TSPO-related protein, resulted in growth defects. However, subcellular fractionation and immunoprecipitation experiments showed that AtTSPO was targeted to mitochondria where it colocalized and interacted with the outer mitochondrial membrane porin VDAC1p, reminiscent of the subcellular localization and activity of mammalian translocator protein 18 kDa TSPO. The evolutionarily divergent AtTSPO appears therefore to be switching its sorting mode in a species-dependent manner, an uncommon peculiarity for a polytopic membrane protein in eukaryotic cells. These results are discussed in relation to the recognition and organelle targeting mechanisms of polytopic membrane proteins in eukaryotic cells. |
| Databáze: | OpenAIRE |
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