Summary: Protein of unknown function (DUF3582)
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Domain of unknown function Edit Wikipedia article
A domain of unknown function (DUF) is a protein domain that has no characterised function. These families have been collected together in the Pfam database using the prefix DUF followed by a number, with examples being DUF2992 and DUF1220. There are now over 3,000 DUF families within the Pfam database representing over 20% of known families.
The DUF naming scheme was introduced by Chris Ponting, through the addition of DUF1 and DUF2 to the SMART database. These two domains were found to be widely distributed in bacterial signaling proteins. Subsequently, the functions of these domains were identified and they have since been renamed as the GGDEF domain and EAL domain respectively.
Structural genomics programmes have attempted to understand the function of DUFs through structure determination. The structures of over 250 DUF families have been solved. This work showed that about two thirds of DUF families had a structure similar to a previously solved one and therefore likely to be divergent members of existing protein superfamilies, whereas about one third possessed a novel protein fold.
Frequency and conservation
More than 20% of all protein domains were annotated as DUFs in 2013. About 2,700 DUFs are found in bacteria compared with just over 1,500 in eukaryotes. Over 800 DUFs are shared between bacteria and eukaryotes, and about 300 of these are also present in archaea. A total of 2,786 bacterial Pfam domains even occur in animals, including 320 DUFs.
Many DUFs are highly conserved, indicating an important role in biology. However, many such DUFs are not essential, hence their biological role often remains unknown. For instance, DUF143 is present in most bacteria and eukaryotic genomes. However, when it was deleted in Escherichia coli no obvious phenotype was obvious. Later it was shown that the proteins that contain DUF143, are ribosomal silencing factors that block the assembly of the two ribosomal subunits. While this function is not essential, it helps the cells to adapt to low nutrient conditions by shutting down protein biosynthesis. As a result, these proteins and the DUF only becomes relevant when the cells starve.
Essential DUFs (eDUFs)
Goodacre et al. identified 238 DUFs in 355 essential proteins (in 16 model bacterial species), most of which represent single-domain proteins, clearly establishing the biological essentiality of DUFs. These DUFs are called "essential DUFs" or eDUFs.
- Bateman A, Coggill P, Finn RD (October 2010). "DUFs: families in search of function". Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 66 (Pt 10): 1148–52. doi:10.1107/S1744309110001685. PMC 2954198. PMID 20944204.
- Schultz J, Milpetz F, Bork P, Ponting CP (May 1998). "SMART, a simple modular architecture research tool: identification of signaling domains". Proc. Natl. Acad. Sci. U.S.A. 95 (11): 5857–64. doi:10.1073/pnas.95.11.5857. PMC 34487. PMID 9600884.
- Jaroszewski L, Li Z, Krishna SS, et al. (September 2009). "Exploration of uncharted regions of the protein universe". PLoS Biol. 7 (9): e1000205. doi:10.1371/journal.pbio.1000205. PMC 2744874. PMID 19787035.
- Goodacre, N. F.; Gerloff, D. L.; Uetz, P. (2013). "Protein Domains of Unknown Function Are Essential in Bacteria". MBio 5 (1): e00744–e00713. doi:10.1128/mBio.00744-13. PMID 24381303.
- Häuser, R.; Pech, M.; Kijek, J.; Yamamoto, H.; Titz, B. R.; Naeve, F.; Tovchigrechko, A.; Yamamoto, K.; Szaflarski, W.; Takeuchi, N.; Stellberger, T.; Diefenbacher, M. E.; Nierhaus, K. H.; Uetz, P. (2012). "RsfA (YbeB) Proteins Are Conserved Ribosomal Silencing Factors". In Hughes, Diarmaid. PLoS Genetics 8 (7): e1002815. doi:10.1371/journal.pgen.1002815. PMC 3400551. PMID 22829778.
"DUF" families are annotated with the Domain of unknown function Wikipedia article. This is a general article, with no specific information about individual Pfam DUFs. If you have information about this particular DUF, please let us know using the "Add annotation" button below.
Protein of unknown function (DUF3582) Provide feedback
This domain is found in bacteria, and is approximately 130 amino acids in length. It is found associated with PF01694. There is a conserved ASW sequence motif. This domain has a single completely conserved residue F that may be functionally important.
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR022732
In the MEROPS database peptidases and peptidase homologues are grouped into clans and families. Clans are groups of families for which there is evidence of common ancestry based on a common structural fold:
- Each clan is identified with two letters, the first representing the catalytic type of the families included in the clan (with the letter 'P' being used for a clan containing families of more than one of the catalytic types serine, threonine and cysteine). Some families cannot yet be assigned to clans, and when a formal assignment is required, such a family is described as belonging to clan A-, C-, M-, N-, S-, T- or U-, according to the catalytic type. Some clans are divided into subclans because there is evidence of a very ancient divergence within the clan, for example MA(E), the gluzincins, and MA(M), the metzincins.
- Peptidase families are grouped by their catalytic type, the first character representing the catalytic type: A, aspartic; C, cysteine; G, glutamic acid; M, metallo; N, asparagine; S, serine; T, threonine; and U, unknown. The serine, threonine and cysteine peptidases utilise the amino acid as a nucleophile and form an acyl intermediate - these peptidases can also readily act as transferases. In the case of aspartic, glutamic and metallopeptidases, the nucleophile is an activated water molecule. In the case of the asparagine endopeptidases, the nucleophile is asparagine and all are self-processing endopeptidases.
In many instances the structural protein fold that characterises the clan or family may have lost its catalytic activity, yet retain its function in protein recognition and binding.
Proteolytic enzymes that exploit serine in their catalytic activity are ubiquitous, being found in viruses, bacteria and eukaryotes [PUBMED:7845208]. They include a wide range of peptidase activity, including exopeptidase, endopeptidase, oligopeptidase and omega-peptidase activity. Many families of serine protease have been identified, these being grouped into clans on the basis of structural similarity and other functional evidence [PUBMED:7845208]. Structures are known for members of the clans and the structures indicate that some appear to be totally unrelated, suggesting different evolutionary origins for the serine peptidases [PUBMED:7845208].
Not withstanding their different evolutionary origins, there are similarities in the reaction mechanisms of several peptidases. Chymotrypsin, subtilisin and carboxypeptidase C have a catalytic triad of serine, aspartate and histidine in common: serine acts as a nucleophile, aspartate as an electrophile, and histidine as a base [PUBMED:7845208]. The geometric orientations of the catalytic residues are similar between families, despite different protein folds [PUBMED:7845208]. The linear arrangements of the catalytic residues commonly reflect clan relationships. For example the catalytic triad in the chymotrypsin clan (PA) is ordered HDS, but is ordered DHS in the subtilisin clan (SB) and SDH in the carboxypeptidase clan (SC) [PUBMED:7845208, PUBMED:8439290].
This entry represents the N-terminal domain of membrane-bound serine endopeptidases belonging to MEROPS peptidase family S54 (rhomboid-1, clan ST). This domain contains a conserved ASW sequence motif and a single completely conserved residue F that may be functionally important.
The tertiary structure of the GlpG protein from Escherichia coli has been determined [PUBMED:1705116]. The GlpG protein has six transmembrane domains (other members of the family are predicted to have seven), with the N- and C-terminal ends anchored in the cytoplasm. One transmembrane domain is shorter than the rest, creating an internal, aqueous cavity just below the membrane surface and it is here were proteolysis occurs. There is also a membrane-embedded loop between the first and second transmembrane domains which is postulated to act as a gate controlling substrate access to the active site. No other family of serine peptidases is known to have active site residues within transmembrane domains (although transmembrane active sites are known for aspartic peptidase and metallopeptidases), and the GlpG protein has the type structure for clan ST.
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||serine-type endopeptidase activity (GO:0004252)|
- the number of sequences which exhibit this architecture
a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- the UniProt description of the protein sequence
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The members of this clan are characterised by the fact the domains, each comprised of four beta-strand and two alpha helices, tend to form tetrameric structures .
The clan contains the following 9 members:CutA1 DUF190 DUF2007 DUF3240 DUF3582 DUF970 HisG_C Nit_Regul_Hom P-II
We make a range of alignments for each Pfam-A family:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the NCBI sequence database using the family HMM
- alignment generated by searching the metagenomics sequence database using the family HMM
You can see the alignments as HTML or in three different sequence viewers:
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Curation and family details
|Seed source:||PFAM-B_2087 (release 23.0)|
|Author:||Assefa S, Bateman A|
|Number in seed:||32|
|Number in full:||749|
|Average length of the domain:||98.80 aa|
|Average identity of full alignment:||56 %|
|Average coverage of the sequence by the domain:||35.72 %|
|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:||3|
|Download:||download the raw HMM for this family|
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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 DUF3582 domain has been found. There are 15 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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