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21  structures 1879  species 0  interactions 2339  sequences 12  architectures

Family: TspO_MBR (PF03073)

Summary: TspO/MBR family

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TspO/MBR family Provide feedback

Tryptophan-rich sensory protein (TspO) is an integral membrane protein that acts as a negative regulator of the expression of specific photosynthesis genes in response to oxygen/light [1]. It is involved in the efflux of porphyrin intermediates from the cell. This reduces the activity of coproporphyrinogen III oxidase, which is thought to lead to the accumulation of a putative repressor molecule that inhibits the expression of specific photosynthesis genes. Several conserved aromatic residues are necessary for TspO function: they are thought to be involved in binding porphyrin intermediates [3]. In [2] the rat mitochondrial peripheral benzodiazepine receptor (MBR) was shown to not only retain its structure within a bacterial outer membrane, but also to be able to functionally substitute for TspO in TspO- mutants, and to act in a similar manner to TspO in its in situ location: the outer mitochondrial membrane. The biological significance of MBR remains unclear, however. It is thought to be involved in a variety of cellular functions, including cholesterol transport in steroidogenic tissues.

Literature references

  1. Yeliseev AA, Kaplan S; , J Biol Chem 1995;270:21167-21175.: A sensory transducer homologous to the mammalian peripheral-type benzodiazepine receptor regulates photosynthetic membrane complex formation in Rhodobacter sphaeroides 2.4.1. PUBMED:7673149 EPMC:7673149

  2. Yeliseev AA, Krueger KE, Kaplan S; , Proc Natl Acad Sci U S A 1997;94:5101-5106.: A mammalian mitochondrial drug receptor functions as a bacterial oxygen sensor. PUBMED:9144197 EPMC:9144197

  3. Yeliseev AA, Kaplan S; , J Biol Chem 2000;275:5657-5667.: TspO of rhodobacter sphaeroides. A structural and functional model for the mammalian peripheral benzodiazepine receptor. PUBMED:10681549 EPMC:10681549


Internal database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR004307

Members of this group are involved in transmembrane signalling. In both prokaryotes and mitochondria they are localized to the outer membrane, and have been shown to bind and transport dicarboxylic tetrapyrrole intermediates of the haem biosynthetic pathway [PUBMED:1373486, PUBMED:7673149]. They are associated with the major outer membrane porins (in prokaryotes) and with the voltage-dependent anion channel (in mitochondria) [PUBMED:8114671].

Rhodobacter sphaeroides TspO (previously CrtK) is involved in signal transduction, functioning as a negative regulator of the expression of some photosynthesis genes (PpsR/AppA repressor/antirepressor regulon). This down-regulation is believed to be in response to oxygen levels. TspO works through (or modulates) the PpsR/AppA system and acts upstream of the site of action of these regulatory proteins [PUBMED:11591680]. 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 [PUBMED:10409680]. A homologue of the TspO protein in Rhizobium meliloti (Sinorhizobium meliloti) is involved in regulating expression of the ndi locus in response to stress conditions [PUBMED:11097914]. There is evidence that the S. meliloti TspO acts through, or in addition to, the FixL regulatory system.

In animals, translocator protein (TSPO), previously known as peripheral-type benzodiazepine receptor (PBR, MBR) is a mitochondrial protein (located in the outer mitochondrial membrane) where it forms a complex with several proteins of the mitochondrial permeability transition pore (MPTP). TSPO is involved in multiple processes, including regulation of cell death, cholesterol transport and steroid biosynthesis, mitochondrial respiration and oxidation and mitochondrial protein import [PUBMED:23518318, PUBMED:22364127].

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.

Gene Ontology

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Domain organisation

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Alignments

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(527)
Full
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(5255)
NCBI
(8192)
Meta
(1229)
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(520)
RP35
(1337)
RP55
(2280)
RP75
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  Seed
(527)
Full
(2339)
Representative proteomes UniProt
(5255)
NCBI
(8192)
Meta
(1229)
RP15
(520)
RP35
(1337)
RP55
(2280)
RP75
(3268)
Alignment:
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  Seed
(527)
Full
(2339)
Representative proteomes UniProt
(5255)
NCBI
(8192)
Meta
(1229)
RP15
(520)
RP35
(1337)
RP55
(2280)
RP75
(3268)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download   Download  
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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

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Trees

This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

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Curation View help on the curation process

Seed source: Pfam-B_1882 (release 6.4)
Previous IDs: none
Type: Family
Author: Mifsud W
Number in seed: 527
Number in full: 2339
Average length of the domain: 143.50 aa
Average identity of full alignment: 27 %
Average coverage of the sequence by the domain: 81.09 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 26740544 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 21.6 21.6
Trusted cut-off 21.6 21.7
Noise cut-off 21.5 21.5
Model length: 135
Family (HMM) version: 14
Download: download the raw HMM for this family

Species distribution

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Structures

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the TspO_MBR domain has been found. There are 21 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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