Tryptophan-rich sensory protein: Difference between revisions
Content deleted Content added
| Line 30: | Line 30: | ||
==Homology== |
==Homology== |
||
A [[Homology (biology)|homologue]] of the TspO protein in [[Rhizobium meliloti]] is involved in regulating [[expression (genetics)|expression]] of the ndi [[locus]] in response to [[Stress (medicine)|stress]] conditions.<ref name="pmid11097914">{{cite journal | author = Davey ME, de Bruijn FJ | title = A homologue of the tryptophan-rich sensory protein TspO and FixL regulate a novel nutrient deprivation-induced Sinorhizobium meliloti locus | journal = Appl. Environ. Microbiol. | volume = 66 | issue = 12 | pages = 5353-9 | year = 2000 | month = December | pmid = 11097914 | pmc = 92468 | doi = | url = }}</ref>. |
A [[Homology (biology)|homologue]] of the TspO protein in [[Rhizobium meliloti]] is involved in regulating [[expression (genetics)|expression]] of the ndi [[locus]] in response to [[Stress (medicine)|stress]] conditions.<ref name="pmid11097914">{{cite journal | author = Davey ME, de Bruijn FJ | title = A homologue of the tryptophan-rich sensory protein TspO and FixL regulate a novel nutrient deprivation-induced Sinorhizobium meliloti locus | journal = Appl. Environ. Microbiol. | volume = 66 | issue = 12 | pages = 5353-9 | year = 2000 | month = December | pmid = 11097914 | pmc = 92468 | doi = | url = }}</ref>. |
||
==PBR== |
|||
In animals, the [[peripheral benzodiazepine receptor]] (PBR) is a mitochondrial protein (located in the [[outer mitochondrial membrane]]) characterised by its ability to bind a variety of [[benzodiazepine]]-like drugs, as well as to dicarboxylic [[tetrapyrrole]] intermediates of the haem biosynthetic pathway. Depending upon the tissue, it was shown to be involved in: |
|||
* [[steroidogenesis]], |
|||
* [[haem biosynthesis]], |
|||
* [[apoptosis]], |
|||
* [[cell growth]], |
|||
* differentiation, |
|||
* [[Electron transport chain|mitochondrial respiratory control]], |
|||
* [[immune system|immune]] |
|||
* [[stress response]], but the precise function of the PBR remains unclear. |
|||
The role of PBR in the regulation of [[cholesterol]] transport from the outer to the inner mitochondrial membrane, the rate-determining step in [[steroid]] biosynthesis, has been studied in detail. PBR is required for the binding, uptake and release, upon [[ligand (biochemistry)|ligand]] activation, of the [[Enzyme substrate|substrate]] cholesterol.<ref name="pmid11806292">{{cite journal | author = Papadopoulos V, Amri H, Li H, Yao Z, Brown RC, Vidic B, Culty M | title = Structure, function and regulation of the mitochondrial peripheral-type benzodiazepine receptor | journal = Therapie | volume = 56 | issue = 5 | pages = 549-56 | year = 2001 | pmid = 11806292 | doi = | url = }}</ref> PBR forms a multimeric [[Protein complex|complex]] with the voltage-dependent anion channel (VDAC) <ref name="pmid8114671">{{cite journal | author = Garnier M, Dimchev AB, Boujrad N, Price JM, Musto NA, Papadopoulos V | title = In vitro reconstitution of a functional peripheral-type benzodiazepine receptor from mouse Leydig tumor cells | journal = Mol. Pharmacol. | volume = 45 | issue = 2 | pages = 201-11 | year = 1994 | month = February | pmid = 8114671 | doi = | url = }}</ref> and [[adenine nucleotide]] carrier.<ref name="pmid1373486">{{cite journal | author = McEnery MW, Snowman AM, Trifiletti RR, Snyder SH | title = Isolation of the mitochondrial benzodiazepine receptor: association with the voltage-dependent anion channel and the adenine nucleotide carrier | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 89 | issue = 8 | pages = 3170-4 | year = 1992 | month = April | pmid = 1373486 | pmc = 48827 | doi = 10.1073/pnas.89.8.3170| url = }}</ref> Molecular modeling of PBR suggested that it might function as a channel for cholesterol. Indeed, cholesterol uptake and transport by bacterial cells was [[Regulation of gene expression|induced]] upon PBR [[Gene expression|expression]]. [[Mutagenesis]] studies identified a cholesterol recognition/interaction [[protein motif|motif]] (CRAC) in the [[cytoplasm|cytoplasmic]] C terminus of PBR.<ref name="pmid11158628">{{cite journal | author = Li H, Yao Z, Degenhardt B, Teper G, Papadopoulos V | title = Cholesterol binding at the cholesterol recognition/ interaction amino acid consensus (CRAC) of the peripheral-type benzodiazepine receptor and inhibition of steroidogenesis by an HIV TAT-CRAC peptide | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 98 | issue = 3 | pages = 1267-72 | year = 2001 | month = January | pmid = 11158628 | pmc = 14743 | doi = 10.1073/pnas.031461598 | url = }}</ref><ref name="pmid12589253">{{cite journal | author = Papadopoulos V | title = Peripheral benzodiazepine receptor: structure and function in health and disease | journal = Ann Pharm Fr | volume = 61 | issue = 1 | pages = 30-50 | year = 2003 | month = January | pmid = 12589253 | doi = | url = }}</ref> |
|||
In [[complementation experiments]], [[rat]] PBR (pk18) protein functionally substitutes for its homologue TspO in R. sphaeroides, negatively affecting [[transcription]] of specific photosynthesis [[gene|genes]].<ref name="pmid9144197">{{cite journal | author = Yeliseev AA, Krueger KE, Kaplan S | title = A mammalian mitochondrial drug receptor functions as a bacterial "oxygen" sensor | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 94 | issue = 10 | pages = 5101-6 | year = 1997 | month = May | pmid = 9144197 | pmc = 24638 | doi = | url = }}</ref> This suggests that PBR may function as an oxygen sensor, transducing an oxygen-triggered signal leading to an adaptive [[cell (biology)|cellular]] response. |
|||
These observations suggest that fundamental aspects of this receptor and the downstream [[signal transduction pathway]] are conserved in bacteria and higher eukaryotic mitochondria. The alpha-3 subdivision of the [[purple bacteria]] is considered to be a likely source of the endosymbiont that ultimately gave rise to the mitochondrion. Therefore, it is possible that the mammalian PBR remains both evolutionarily and functionally related to the TspO of R. sphaeroides. |
|||
==References== |
==References== |
||
Revision as of 16:00, 19 July 2012
| TspO_MBR | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | TspO_MBR | ||||||||
| Pfam | PF03073 | ||||||||
| InterPro | IPR004307 | ||||||||
| |||||||||
Tryptophan-rich sensory proteins (TspO) are a family of proteins that are involved in transmembrane signalling.
Localisation
In both prokaryotes and mitochondria they are found bound to the outer membrane. They are associated with the major outer membrane porins (in prokaryotes) and with the voltage-dependent anion channel (in mitochondria).[1]
Function
TspO has been shown to bind to and transport dicarboxylic tetrapyrrole intermediates of the haem biosynthetic pathway.[2][3]
Also, TspO of Rhodobacter sphaeroides is involved in signal transduction. TspO negatively regulates the expression of photosynthesis genes (PpsR/AppA repressor/antirepressor regulon). This down-regulation occurs in response to oxygen levels. TspO works through the PpsR/AppA system and acts upstream of the site of action of these regulatory proteins.[4] It has been suggested that the TspO regulatory pathway works by regulating the efflux of certain tetrapyrrole intermediates of the haem/bacteriochlorophyll biosynthetic pathways in response to the availability of molecular oxygen, thereby causing the accumulation of a biosynthetic intermediate that serves as a corepressor for the regulated genes.[5]
Homology
A homologue of the TspO protein in Rhizobium meliloti is involved in regulating expression of the ndi locus in response to stress conditions.[6].
References
- ^ Garnier M, Dimchev AB, Boujrad N, Price JM, Musto NA, Papadopoulos V (1994). "In vitro reconstitution of a functional peripheral-type benzodiazepine receptor from mouse Leydig tumor cells". Mol. Pharmacol. 45 (2): 201–11. PMID 8114671.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ McEnery MW, Snowman AM, Trifiletti RR, Snyder SH (1992). "Isolation of the mitochondrial benzodiazepine receptor: association with the voltage-dependent anion channel and the adenine nucleotide carrier". Proc. Natl. Acad. Sci. U.S.A. 89 (8): 3170–4. doi:10.1073/pnas.89.8.3170. PMC 48827. PMID 1373486.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Yeliseev AA, Kaplan S (1995). "A sensory transducer homologous to the mammalian peripheral-type benzodiazepine receptor regulates photosynthetic membrane complex formation in Rhodobacter sphaeroides 2.4.1". J. Biol. Chem. 270 (36): 21167–75. PMID 7673149.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Zeng X, Kaplan S (2001). "TspO as a modulator of the repressor/antirepressor (PpsR/AppA) regulatory system in Rhodobacter sphaeroides 2.4.1". J. Bacteriol. 183 (21): 6355–64. doi:10.1128/JB.183.21.6355-6364.2001. PMC 100131. PMID 11591680.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Yeliseev AA, Kaplan S (1999). "A novel mechanism for the regulation of photosynthesis gene expression by the TspO outer membrane protein of Rhodobacter sphaeroides 2.4.1". J. Biol. Chem. 274 (30): 21234–43. PMID 10409680.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Davey ME, de Bruijn FJ (2000). "A homologue of the tryptophan-rich sensory protein TspO and FixL regulate a novel nutrient deprivation-induced Sinorhizobium meliloti locus". Appl. Environ. Microbiol. 66 (12): 5353–9. PMC 92468. PMID 11097914.
{{cite journal}}: Unknown parameter|month=ignored (help)