The <it>Arabidopsis </it>translocator protein (<it>At</it>TSPO) is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolism
<p>Abstract</p> <p>Background</p> <p>The translocator protein 18 kDa (TSPO), previously known as the peripheral-type benzodiazepine receptor (PBR), is important for many cellular functions in mammals and bacteria, such as steroid biosynthesis, cellular respiration, cell...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMC
2011-06-01
|
| Series: | BMC Plant Biology |
| Subjects: | |
| Online Access: | http://www.biomedcentral.com/1471-2229/11/108 |
| _version_ | 1818766184814739456 |
|---|---|
| author | Umen James G Andrade Leonardo R Olson Bradley JSC Jaillais Yvon Balsemão-Pires Emilia Chory Joanne Sachetto-Martins Gilberto |
| author_facet | Umen James G Andrade Leonardo R Olson Bradley JSC Jaillais Yvon Balsemão-Pires Emilia Chory Joanne Sachetto-Martins Gilberto |
| author_sort | Umen James G |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>The translocator protein 18 kDa (TSPO), previously known as the peripheral-type benzodiazepine receptor (PBR), is important for many cellular functions in mammals and bacteria, such as steroid biosynthesis, cellular respiration, cell proliferation, apoptosis, immunomodulation, transport of porphyrins and anions. <it>Arabidopsis thaliana </it>contains a single <it>TSPO/PBR</it>-related gene with a 40 amino acid N-terminal extension compared to its homologs in bacteria or mammals suggesting it might be chloroplast or mitochondrial localized.</p> <p>Results</p> <p>To test if the TSPO N-terminal extension targets it to organelles, we fused three potential translational start sites in the <it>TSPO </it>cDNA to the N-terminus of GFP (<it>At</it>TSPO:eGFP). The location of the <it>At</it>TSPO:eGFP fusion protein was found to depend on the translational start position and the conditions under which plants were grown. Full-length <it>At</it>TSPO:eGFP fusion protein was found in the endoplasmic reticulum and in vesicles of unknown identity when plants were grown in standard conditions. However, full length <it>At</it>TSPO:eGFP localized to chloroplasts when grown in the presence of 150 mM NaCl, conditions of salt stress. In contrast, when <it>At</it>TSPO:eGFP was truncated to the second or third start codon at amino acid position 21 or 42, the fusion protein co-localized with a mitochondrial marker in standard conditions. Using promoter <it>GUS </it>fusions, qRT-PCR, fluorescent protein tagging, and chloroplast fractionation approaches, we demonstrate that <it>At</it>TSPO levels are regulated at the transcriptional, post-transcriptional and post-translational levels in response to abiotic stress conditions. Salt-responsive genes are increased in a <it>tspo-1 knock-down </it>mutant compared to wild type under conditions of salt stress, while they are decreased when <it>At</it>TSPO is overexpressed. Mutations in tetrapyrrole biosynthesis genes and the application of chlorophyll or carotenoid biosynthesis inhibitors also affect <it>AtTSPO </it>expression.</p> <p>Conclusion</p> <p>Our data suggest that AtTSPO plays a role in the response of <it>Arabidopsis </it>to high salt stress. Salt stress leads to re-localization of the AtTSPO from the ER to chloroplasts through its N-terminal extension. In addition, our results show that <it>AtTSPO </it>is regulated at the transcriptional level in tetrapyrrole biosynthetic mutants. Thus, we propose that <it>At</it>TSPO may play a role in transporting tetrapyrrole intermediates during salt stress and other conditions in which tetrapyrrole metabolism is compromised.</p> |
| first_indexed | 2024-12-18T08:29:57Z |
| format | Article |
| id | doaj.art-3807f3d4558e4a60b6142886d763a25b |
| institution | Directory Open Access Journal |
| issn | 1471-2229 |
| language | English |
| last_indexed | 2024-12-18T08:29:57Z |
| publishDate | 2011-06-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Plant Biology |
| spelling | doaj.art-3807f3d4558e4a60b6142886d763a25b2022-12-21T21:14:29ZengBMCBMC Plant Biology1471-22292011-06-0111110810.1186/1471-2229-11-108The <it>Arabidopsis </it>translocator protein (<it>At</it>TSPO) is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolismUmen James GAndrade Leonardo ROlson Bradley JSCJaillais YvonBalsemão-Pires EmiliaChory JoanneSachetto-Martins Gilberto<p>Abstract</p> <p>Background</p> <p>The translocator protein 18 kDa (TSPO), previously known as the peripheral-type benzodiazepine receptor (PBR), is important for many cellular functions in mammals and bacteria, such as steroid biosynthesis, cellular respiration, cell proliferation, apoptosis, immunomodulation, transport of porphyrins and anions. <it>Arabidopsis thaliana </it>contains a single <it>TSPO/PBR</it>-related gene with a 40 amino acid N-terminal extension compared to its homologs in bacteria or mammals suggesting it might be chloroplast or mitochondrial localized.</p> <p>Results</p> <p>To test if the TSPO N-terminal extension targets it to organelles, we fused three potential translational start sites in the <it>TSPO </it>cDNA to the N-terminus of GFP (<it>At</it>TSPO:eGFP). The location of the <it>At</it>TSPO:eGFP fusion protein was found to depend on the translational start position and the conditions under which plants were grown. Full-length <it>At</it>TSPO:eGFP fusion protein was found in the endoplasmic reticulum and in vesicles of unknown identity when plants were grown in standard conditions. However, full length <it>At</it>TSPO:eGFP localized to chloroplasts when grown in the presence of 150 mM NaCl, conditions of salt stress. In contrast, when <it>At</it>TSPO:eGFP was truncated to the second or third start codon at amino acid position 21 or 42, the fusion protein co-localized with a mitochondrial marker in standard conditions. Using promoter <it>GUS </it>fusions, qRT-PCR, fluorescent protein tagging, and chloroplast fractionation approaches, we demonstrate that <it>At</it>TSPO levels are regulated at the transcriptional, post-transcriptional and post-translational levels in response to abiotic stress conditions. Salt-responsive genes are increased in a <it>tspo-1 knock-down </it>mutant compared to wild type under conditions of salt stress, while they are decreased when <it>At</it>TSPO is overexpressed. Mutations in tetrapyrrole biosynthesis genes and the application of chlorophyll or carotenoid biosynthesis inhibitors also affect <it>AtTSPO </it>expression.</p> <p>Conclusion</p> <p>Our data suggest that AtTSPO plays a role in the response of <it>Arabidopsis </it>to high salt stress. Salt stress leads to re-localization of the AtTSPO from the ER to chloroplasts through its N-terminal extension. In addition, our results show that <it>AtTSPO </it>is regulated at the transcriptional level in tetrapyrrole biosynthetic mutants. Thus, we propose that <it>At</it>TSPO may play a role in transporting tetrapyrrole intermediates during salt stress and other conditions in which tetrapyrrole metabolism is compromised.</p>http://www.biomedcentral.com/1471-2229/11/108plant TSPOsubcellular localizationabiotic stressregulationchloroplast |
| spellingShingle | Umen James G Andrade Leonardo R Olson Bradley JSC Jaillais Yvon Balsemão-Pires Emilia Chory Joanne Sachetto-Martins Gilberto The <it>Arabidopsis </it>translocator protein (<it>At</it>TSPO) is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolism BMC Plant Biology plant TSPO subcellular localization abiotic stress regulation chloroplast |
| title | The <it>Arabidopsis </it>translocator protein (<it>At</it>TSPO) is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolism |
| title_full | The <it>Arabidopsis </it>translocator protein (<it>At</it>TSPO) is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolism |
| title_fullStr | The <it>Arabidopsis </it>translocator protein (<it>At</it>TSPO) is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolism |
| title_full_unstemmed | The <it>Arabidopsis </it>translocator protein (<it>At</it>TSPO) is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolism |
| title_short | The <it>Arabidopsis </it>translocator protein (<it>At</it>TSPO) is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolism |
| title_sort | it arabidopsis it translocator protein it at it tspo is regulated at multiple levels in response to salt stress and perturbations in tetrapyrrole metabolism |
| topic | plant TSPO subcellular localization abiotic stress regulation chloroplast |
| url | http://www.biomedcentral.com/1471-2229/11/108 |
| work_keys_str_mv | AT umenjamesg theitarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT andradeleonardor theitarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT olsonbradleyjsc theitarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT jaillaisyvon theitarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT balsemaopiresemilia theitarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT choryjoanne theitarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT sachettomartinsgilberto theitarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT umenjamesg itarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT andradeleonardor itarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT olsonbradleyjsc itarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT jaillaisyvon itarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT balsemaopiresemilia itarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT choryjoanne itarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism AT sachettomartinsgilberto itarabidopsisittranslocatorproteinitatittspoisregulatedatmultiplelevelsinresponsetosaltstressandperturbationsintetrapyrrolemetabolism |