ABA, porphyrins and plant TSPO-related protein

Guillaumot, Damien; Guillon, Stéphanie; Morsomme, Pierre; Batoko, Henri

doi:10.4161/psb.4.11.9796

Cited by 27 publications

(29 citation statements)

References 14 publications

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“…Even when constitutively expressed, TSPO fails to accumulate evenly in all cell types and, in particular, does not accumulate in mesophyll cells (Guillaumot et al, 2009a). Overexpression of the protein can be detrimental under certain physiological conditions, and boosting tetrapyrrole biosynthesis through d-aminolevulinic acid (ALA) feeding enhances plant cell degradation of At-TSPO, suggesting that posttranslational regulation of TSPO may involve tetrapyrroles (Guillaumot et al, 2009a(Guillaumot et al, , 2009b. To test this possibility and to identify the key player(s) involved, we used defined pharmacological agents to tamper with tetrapyrrole biosynthesis.…”

Section: Heme Metabolism Affects Tspo Stability In the Plant Cellmentioning

confidence: 99%

“…We previously showed that overexpression of At-TSPO can be detrimental to plant cells (Guillaumot et al, 2009a). ABA-induced expression of TSPO in vegetative tissue is transient, and the degradation of induced or constitutively expressed TSPO is enhanced by boosting tetrapyrrole biosynthesis (Guillaumot et al, 2009a(Guillaumot et al, , 2009b, suggesting that posttranslational regulation of TSPO may depend on tetrapyrrole metabolism.…”

Section: Introductionmentioning

confidence: 99%

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TheArabidopsisMultistress Regulator TSPO Is a Heme Binding Membrane Protein and a Potential Scavenger of Porphyrins via an Autophagy-Dependent Degradation Mechanism

et al. 2011

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TSPO, a stress-induced, posttranslationally regulated, early secretory pathway-localized plant cell membrane protein, belongs to the TspO/MBR family of regulatory proteins, which can bind porphyrins. This work finds that boosting tetrapyrrole biosynthesis enhanced TSPO degradation in Arabidopsis thaliana and that TSPO could bind heme in vitro and in vivo. This binding required the His residue at position 91 (H91), but not that at position 115 (H115). The H91A and double H91A/H115A substitutions stabilized TSPO and rendered the protein insensitive to heme-regulated degradation, suggesting that heme binding regulates At-TSPO degradation. TSPO degradation was inhibited in the autophagy-defective atg5 mutant and was sensitive to inhibitors of type III phosphoinositide 3-kinases, which regulate autophagy in eukaryotic cells. Mutation of the two Tyr residues in a putative ubiquitin-like ATG8 interacting motif of At-TSPO did not affect heme binding in vitro but stabilized the protein in vivo, suggesting that downregulation of At-TSPO requires an active autophagy pathway, in addition to heme. Abscisic acid-dependent TSPO induction was accompanied by an increase in unbound heme levels, and downregulation of TSPO coincided with the return to steady state levels of unbound heme, suggesting that a physiological consequence of active TSPO downregulation may be heme scavenging. In addition, overexpression of TSPO attenuated aminolevulinic acid-induced porphyria in plant cells. Taken together, these data support a role for TSPO in porphyrin binding and scavenging during stress in plants.

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Section: Heme Metabolism Affects Tspo Stability In the Plant Cellmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

TheArabidopsisMultistress Regulator TSPO Is a Heme Binding Membrane Protein and a Potential Scavenger of Porphyrins via an Autophagy-Dependent Degradation Mechanism

et al. 2011

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“…The highest level of expression was found in germinating seeds [39]. The intracellular distribution, however, is contradictory; PpTSPO1-GFP constructs is localized to mitochondria [13], whereas AtTSPO-GFP was localized to the Golgi and ER [40]. However, A. thaliana, Digitalis lanata (foxglove), and S. tuberosum mitochondria had high affinity Ro5-4864 binding [27].…”

Section: Tspo In Plantsmentioning

confidence: 74%

“…Specifically, PpTSPO, AtTSPO, and StTSPO have roles in abiotic stress adaptation [13,[40][41][42][43], which is mediated by ABA. The ABA-dependent induction of AtTSPO is apparently linked to tetrapyrrole metabolism [13,40,44]. Interestingly, magnesium deficiency also induces expression of AtTSPO (At2g47770), by a mechanism involving ABA signaling [45].…”

Section: Tspo In Plantsmentioning

confidence: 99%

Structural and Functional Evolution of the Translocator Protein (18 kDa)

Fan¹,

Lindemann²,

Feuilloley³

et al. 2012

Current Molecular Medicine

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Translocator proteins (TSPO) are the products of a family of genes that is evolutionarily conserved from bacteria to humans and expressed in most mammalian tissues and cells. Human TSPO (18 kDa) is expressed at high levels in steroid synthesizing endocrine tissues where it localizes to mitochondria and functions in the first step of steroid formation, the transport of cholesterol into the mitochondria. TSPO expression is elevated in cancerous tissues and during tissue injury, which has lead to the hypothesis that TSPO has roles in apoptosis and the maintenance of mitochondrial integrity. We recently identified a new paralog of Tspo in both the human and mouse. This paralog arose from an ancient gene duplication event before the divergence of the classes aves and mammals, and appears to have specialized tissue-, cell-, and organelle-specific functions. Evidence from the study of TSPO homologs in mammals, bacteria, and plants supports the conclusion that the TSPO family of proteins regulates specialized functions related to oxygenmediated metabolism. In this review, we provide a comprehensive overview of the divergent function and evolutionary origin of Tspo genes in Bacteria, Archaea, and Eukarya domains.

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“…This was also true when At-TSPO was constitutively expressed in transgenic Arabidopsis plant. 4,5 Overexpression of At-TSPO in cultured Arabidopsis cells rendered these cells more sensitive to salt stress. These observations suggest some level of developmental and cell-type-dependent posttranscriptional and/or post -translational regulation of At-TSPO.…”

Section: O N O T D I S T R I B U T Ementioning

confidence: 99%