Summary: Arsenical pump membrane protein
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Ars operon Edit Wikipedia article
yffb (pa3664) protein
In molecular biology, the ars operon is an operon found in several bacterial taxon. It is required for the detoxification of arsenate, arsenite, and antimonite. This system transports arsenite and antimonite out of the cell. The pump is composed of two polypeptides, the products of the arsA and arsB genes. This two-subunit enzyme produces resistance to arsenite and antimonite. Arsenate, however, must first be reduced to arsenite before it is extruded. A third gene, arsC, expands the substrate specificity to allow for arsenate pumping and resistance. ArsC is an approximately 150-residue arsenate reductase that uses reduced glutathione (GSH) to convert arsenate to arsenite with a redox active cysteine residue in the active site. ArsC forms an active quaternary complex with GSH, arsenate, and glutaredoxin 1 (Grx1). The three ligands must be present simultaneously for reduction to occur.
ArsA and ArsB
ArsA and ArsB form an anion-translocating ATPase. The ArsB protein is distinguished by its overall hydrophobic character, in keeping with its role as a membrane-associated channel. Sequence analysis reveals the presence of 13 putative transmembrane (TM) regions.
The arsC protein structure has been solved. It belongs to the thioredoxin superfamily fold which is defined by a beta-sheet core surrounded by alpha-helices. The active cysteine residue of ArsC is located in the loop between the first beta-strand and the first helix, which is also conserved in the Spx protein and its homologues.
ArsD and ArsR
ArsD is a trans-acting repressor of the arsRDABC operon that confers resistance to arsenicals and antimonials in Escherichia coli. It possesses two-pairs of vicinal cysteine residues, Cys(12)-Cys(13) and Cys(112)-Cys(113), that potentially form separate binding sites for the metalloids that trigger dissociation of ArsD from the operon. However, as a homodimer it has four vicinal cysteine pairs. The ArsD family consists of several bacterial arsenical resistance operon trans-acting repressor ArsD proteins.
ArsR is a trans-acting regulatory protein. It acts as a repressor on the arsRDABC operon when no arsenic is present in the cell. When arsenic is present in the cell ArsR will lose affinity for the operator and RNA polymerase can transcribe the arsDCAB genes. ArsD and ArsR work together to regulate the ars operon.
- Carlin A, Shi W, Dey S, Rosen BP (February 1995). "The ars operon of Escherichia coli confers arsenical and antimonial resistance". J. Bacteriol. 177 (4): 981–6. PMC 176692. PMID 7860609.
- Liu J, Rosen BP (August 1997). "Ligand interactions of the ArsC arsenate reductase". J. Biol. Chem. 272 (34): 21084–9. doi:10.1074/jbc.272.34.21084. PMID 9261111.
- Rosen BP (1990). "The plasmid-encoded arsenical resistance pump: an anion-translocating ATPase.". Res Microbiol 141 (3): 336–41. PMID 1704144.
- Martin P, DeMel S, Shi J, Gladysheva T, Gatti DL, Rosen BP, Edwards BF (November 2001). "Insights into the structure, solvation, and mechanism of ArsC arsenate reductase, a novel arsenic detoxification enzyme". Structure 9 (11): 1071–81. doi:10.1016/S0969-2126(01)00672-4. PMID 11709171.
- Zuber P (April 2004). "Spx-RNA polymerase interaction and global transcriptional control during oxidative stress". J. Bacteriol. 186 (7): 1911–8. PMC 374421. PMID 15028674.
- Li S, Rosen BP, Borges-Walmsley MI, Walmsley AR (July 2002). "Evidence for cooperativity between the four binding sites of dimeric ArsD, an As(III)-responsive transcriptional regulator". J. Biol. Chem. 277 (29): 25992–6002. doi:10.1074/jbc.M201619200. PMID 11980902.
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Arsenical pump membrane protein Provide feedback
No Pfam abstract.
Internal database links
|Similarity to PfamA using HHSearch:||CitMHS|
External database links
|Transporter classification:||2.A.45 3.A.4|
This tab holds annotation information from the InterPro database.
InterPro entry IPR000802
Arsenic is a toxic metalloid whose trivalent and pentavalent ions inhibit a variety of biochemical processes. Operons that encode arsenic resistance have been found in multicopy plasmids from both Gram-positive and Gram-negative bacteria [PUBMED:7721697]. The resistance mechanism is encoded from a single operon, which houses an anion pump. The pump has two polypeptide components: a catalytic subunit (the ArsA protein), which functions as an oxyanion-stimulated ATPase; and an arsenite export component (the ArsB protein), which is associated with the inner membrane [PUBMED:1688427]. The ArsA and ArsB proteins are thought to form a membrane complex that functions as an anion-translocating ATPase.
The ArsB protein is distinguished by its overall hydrophobic character, in keeping with its role as a membrane-associated channel. Sequence analysis reveals the presence of 13 putative transmembrane (TM) regions.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||integral to membrane (GO:0016021)|
|Molecular function||arsenite transmembrane transporter activity (GO:0015105)|
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This superfamily of secondary carriers specific for cationic and anionic compounds, has been termed the ion transporter (IT) superfamily .
The clan contains the following 17 members:ABG_transport ArsB CitMHS DctM DcuA_DcuB DcuC DUF1504 DUF1646 DUF401 GntP_permease Lactate_perm MatC_N Na_H_antiport_2 Na_H_antiporter Na_sulph_symp NhaB SCFA_trans
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
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We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.
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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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|Author:||Mian N, Bateman A|
|Number in seed:||4|
|Number in full:||1841|
|Average length of the domain:||367.80 aa|
|Average identity of full alignment:||44 %|
|Average coverage of the sequence by the domain:||95.11 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||10|
|Download:||download the raw HMM for this family|
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Unmapped species names
The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.
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Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.
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The tree shows the occurrence of this domain across different species. More...
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For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.
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We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.
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