Summary: AAA domain
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AAA proteins Edit Wikipedia article
For other uses see AAA (disambiguation)
|ATPases associated with diverse cellular activities (AAA)|
Structure of N-ethylmaleimide-sensitive factor.
AAA or AAA+ is an abbreviation for ATPases Associated with diverse cellular Activities. They share a common conserved module of approximately 230 amino acid residues. This is a large, functionally diverse protein family belonging to the AAA+ superfamily of ring-shaped P-loop NTPases, which exert their activity through the energy-dependent remodeling or translocation of macromolecules.
AAA proteins are functionally and organizationally diverse, and vary in activity, stability, and mechanism. Members of the AAA family are found in all organisms and they are essential for many cellular functions. They are involved in processes such as DNA replication, protein degradation, membrane fusion, microtubule severing, peroxisome biogenesis, signal transduction and the regulation of gene expression.
Structure and classification
The AAA+ domain contains two subdomains, an N-terminal alpha/beta domain that binds and hydrolyzes nucleotides (a Rossman fold) and a C-terminal alpha-helical domain. The N-terminal domain is 200-250 amino acids long and contains Walker A and Walker B motifs, and is shared in common with other P-loop NTPases, the superfamily which includes the AAA+ family. Most AAA+ proteins have additional domains that are used for oligomerization, substrate binding and/or regulation. These domains can lie N- or C-terminal to the AAA+ module.
Some classes of AAA proteins have an N-terminal non-ATPase domain which is followed by either one or two AAA domains (D1 and D2). In some proteins with two AAA domains, both are evolutionarily well conserved (like in Cdc48/p97). In others, either the D2 domain (like in Pex1p and Pex6p) or the D1 domain (in Sec18p/NSF) is better conserved in evolution.
While the classical AAA family was based on motifs, the family has been expanded using structural information and is now termed the AAA+ family.
AAA+ proteins are divided into seven basic clades, based on secondary structure elements included within or near the core AAA+ fold: clamp loader, initiator, classic, superfamily III helicase, HCLR, H2-insert, and PS-II insert.
AAA ATPases assemble into oligomeric assemblies (often homo-hexamers) that form a ring-shaped structure with a central pore. These proteins produce a molecular motor that couples ATP binding and hydrolysis to changes in conformational states that can be propagated through the assembly in order to act upon a target substrate, either translocating or remodelling the substrate.
The central pore may be involved in substrate processing. In the hexameric configuration, the ATP-binding site is positioned at the interface between the subunits. Upon ATP binding and hydrolysis, AAA enzymes undergo conformational changes in the AAA-domains as well as in the N-domains. These motions can be transmitted to substrate protein.
ATP hydrolysis by AAA+ ATPases is proposed to involve nucleophilic attack on the ATP gamma-phosphate by an activated water molecule, leading to movement of the N-terminal and C-terminal AAA+ subdomains relative to each other. This movement allows the exertion of mechanical force, amplified by other ATPase domains within the same oligomeric structure. The additional domains in the protein allow for regulation or direction of the force towards different goals.
AAA proteins are not restricted to eukaryotes. Prokaryotes have AAA which combine chaperone with proteolytic activity, for example in ClpAPS complex, which mediates protein degradation and recognition in E. coli. The basic recognition of proteins by AAAs is thought to occur through unfolded domains in the substrate protein. In HslU, a bacterial ClpX/ClpY homologue of the HSP100 family of AAA+ proteins, the N- and C-terminal subdomains move towards each other when nucleotides are bound and hydrolysed. The terminal domains are most distant in the nucleotide-free state and closest in the ADP-bound state. Thereby the opening of the central cavity is affected.
AAA+ proteins are involved in protein degradation, membrane fusion, DNA replication, microtubule dynamics, intracellular transport, transcriptional activation, protein refolding, disassembly of protein complexes and protein aggregates.
The AAA-type ATPase Cdc48p/p97 is perhaps the best-studied AAA protein. Misfolded secretory proteins are exported from the endoplasmic reticulum (ER) and degraded by the ER-associated degradation pathway (ERAD). Nonfunctional membrane and luminal proteins are extracted from the ER and degraded in the cytosol by proteasomes. Substrate retrotranslocation and extraction is assisted by the Cdc48p(Ufd1p/Npl4p) complex on the cytosolic side of the membrane. On the cytosolic side, the substrate is ubiquitinated by ER-based E2 and E3 enzymes before degradation by the 26S proteasome.
Targeting to multivesicular bodies
Multivesicular bodies are endosomal compartments that sort ubiquitinated membrane proteins by incorporating them into vesicles. This process involves the sequential action of three multiprotein complexes, ESCRT I to III (ESCRT standing for 'endosomal sorting complexes required for transport'). Vps4p is a AAA-type ATPase involved in this MVB sorting pathway. It had originally been identified as a ”class E” vps (vacuolar protein sorting) mutant and was subsequently shown to catalyse the dissociation of ESCRT complexes. Vps4p is anchored via Vps46p to the endosomal membrane. Vps4p assembly is assisted by the conserved Vta1p protein, which regulates its oligomerzation status and ATPase activity.
AAA proteases use the energy from ATP hydrolysis to translocate a protein inside the protease for degradation.
Human proteins containing this domain
AFG3L1; AFG3L2; AK6; ATAD1; ATAD2; ATAD2B; ATAD3A; ATAD3B; ATAD3C; BCS1L; CDC6; CHTF18; CINAP; FIGN; FIGNL1; FTSH; IQCA; KATNA1; KATNAL1; KATNAL2; LONP1; LONP2; NSF; NVL; Nbla10058; ORC1L; PEX1; PEX6; PSMC1; PSMC2; PSMC3; PSMC4; PSMC5; PSMC6; RFC1; RFC2; RFC4; RFC5; RUVBL1; RUVBL2; SPAF; SPAST; SPATA5L1; SPG7; TRIP13; VCP; VPS4A; VPS4B; WRNIP1; YME1L1;
- Snider J, Houry WA (February 2008). "AAA+ proteins: diversity in function, similarity in structure". Biochem. Soc. Trans. 36 (Pt 1): 72–7. doi:10.1042/BST0360072. PMID 18208389.
- White SR, Lauring B (December 2007). "AAA+ ATPases: achieving diversity of function with conserved machinery". Traffic 8 (12): 1657–67. doi:10.1111/j.1600-0854.2007.00642.x. PMID 17897320.
- Yu RC, Hanson PI, Jahn R, Brünger AT (September 1998). "Structure of the ATP-dependent oligomerization domain of N-ethylmaleimide sensitive factor complexed with ATP". Nat. Struct. Biol. 5 (9): 803–11. doi:10.1038/1843. PMID 9731775.
- Koonin EV, Aravind L, Leipe DD, Iyer LM (2004). "Evolutionary history and higher order classification of AAA+ ATPases". J. Struct. Biol. 146 (1–2): 11–31. doi:10.1016/j.jsb.2003.10.010. PMID 15037234.
- Lupas AN, Frickey T (2004). "Phylogenetic analysis of AAA proteins". J. Struct. Biol. 146 (1–2): 2–10. doi:10.1016/j.jsb.2003.11.020. PMID 15037233.
- Erzberger JP, Berger JM (2006). "Evolutionary relationships and structural mechanisms of AAA+ proteins". Annu. Rev. Biophys. Biomol. Struct. 35: 93–114. doi:10.1146/annurev.biophys.35.040405.101933. PMID 16689629.
- Hanson PI, Whiteheart SW (July 2005). "AAA+ proteins: have engine, will work". Nat. Rev. Mol. Cell Biol. 6 (7): 519–29. doi:10.1038/nrm1684. PMID 16072036.
- Snider J, Thibault G, Houry WA (2008). "The AAA+ superfamily of functionally diverse proteins". Genome Biol. 9 (4): 216. doi:10.1186/gb-2008-9-4-216. PMC 2643927. PMID 18466635.
- Smith DM, Benaroudj N, Goldberg A (2006). "Proteasomes and their associated ATPases: A destructive combination". J. Struct. Biol. 156 (1): 72–83. doi:10.1016/j.jsb.2006.04.012. PMID 16919475.
- Tucker PA, Sallai L (December 2007). "The AAA+ superfamily--a myriad of motions". Curr. Opin. Struct. Biol. 17 (6): 641–52. doi:10.1016/j.sbi.2007.09.012. PMID 18023171.
- Carter AP, Vale RD (February 2010). "Communication between the AAA+ ring and microtubule-binding domain of dynein". Biochem Cell Biol. 88 (1): 15–21. doi:10.1139/o09-127. PMID 20130675.
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Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
The graphic that is shown by default represents the longest sequence with a given architecture. Each row contains the following information:
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a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
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AAA family proteins often perform chaperone-like functions that assist in the assembly, operation, or disassembly of protein complexes .
The clan contains the following 198 members:6PF2K AAA AAA-ATPase_like AAA_10 AAA_11 AAA_12 AAA_13 AAA_14 AAA_15 AAA_16 AAA_17 AAA_18 AAA_19 AAA_2 AAA_21 AAA_22 AAA_23 AAA_24 AAA_25 AAA_26 AAA_27 AAA_28 AAA_29 AAA_3 AAA_30 AAA_31 AAA_32 AAA_33 AAA_34 AAA_35 AAA_4 AAA_5 AAA_6 AAA_7 AAA_8 AAA_9 AAA_PrkA ABC_ATPase ABC_tran ABC_tran_2 Adeno_IVa2 Adenylsucc_synt ADK AFG1_ATPase AIG1 APS_kinase Arch_ATPase Arf ArgK ArsA_ATPase ATP-synt_ab ATP_bind_1 ATP_bind_2 Bac_DnaA CbiA CMS1 CoaE CobA_CobO_BtuR CobU cobW CPT CTP_synth_N Cytidylate_kin Cytidylate_kin2 DAP3 DEAD DEAD_2 DLIC DNA_pack_C DNA_pack_N DNA_pol3_delta DNA_pol3_delta2 DnaB_C dNK DUF1253 DUF1611 DUF2075 DUF2478 DUF258 DUF2791 DUF2813 DUF3584 DUF463 DUF815 DUF853 DUF87 DUF927 Dynamin_N Exonuc_V_gamma FeoB_N Fer4_NifH Flavi_DEAD FTHFS FtsK_SpoIIIE G-alpha Gal-3-0_sulfotr GBP GTP_EFTU GTP_EFTU_D2 GTP_EFTU_D4 Gtr1_RagA Guanylate_kin GvpD HDA2-3 Helicase_C Helicase_C_2 Helicase_C_4 Helicase_RecD Herpes_Helicase Herpes_ori_bp Herpes_TK IIGP IPPT IPT IstB_IS21 KaiC KAP_NTPase Kinesin Kinesin-relat_1 Kinesin-related KTI12 LpxK MCM MEDS Mg_chelatase Mg_chelatase_2 MipZ Miro MMR_HSR1 MobB MukB MutS_V Myosin_head NACHT NB-ARC NOG1 NTPase_1 ParA Parvo_NS1 PAXNEB PduV-EutP PhoH PIF1 Podovirus_Gp16 Polyoma_lg_T_C Pox_A32 PPK2 PPV_E1_C PRK Rad17 Rad51 Ras RecA ResIII RHD3 RHSP RNA12 RNA_helicase RuvB_N SbcCD_C SecA_DEAD Septin Sigma54_activ_2 Sigma54_activat SKI SMC_N SNF2_N Spore_IV_A SRP54 SRPRB Sulfotransfer_1 Sulfotransfer_2 Sulfotransfer_3 Sulphotransf T2SE T4SS-DNA_transf Terminase_1 Terminase_3 Terminase_6 Terminase_GpA Thymidylate_kin TIP49 TK TniB Torsin TraG-D_C tRNA_lig_kinase TrwB_AAD_bind UPF0079 UvrD-helicase UvrD_C UvrD_C_2 Viral_helicase1 VirC1 VirE YhjQ Zeta_toxin Zot
We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the NCBI sequence database, and our metagenomics sequence database. More...
There are various ways to view or download the sequence alignments that we store. We provide several sequence viewers and a plain-text Stockholm-format file for download.
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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You can download (or view in your browser) a text representation of a Pfam alignment in various formats:
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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.
1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
Format an alignment
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.
You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.
MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.
HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...
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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.
Note: You can also download the data file for the tree.
Curation and family details
This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.
|Number in seed:||412|
|Number in full:||3187|
|Average length of the domain:||153.40 aa|
|Average identity of full alignment:||15 %|
|Average coverage of the sequence by the domain:||55.53 %|
|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:||1|
|Download:||download the raw HMM for this family|
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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the More....
This chart is a modified "sunburst" visualisation of the species tree for this family. It shows each node in the tree as a separate arc, arranged radially with the superkingdoms at the centre and the species arrayed around the outermost ring.
How the sunburst is generated
The tree is built by considering the taxonomic lineage of each sequence that has a match to this family. For each node in the resulting tree, we draw an arc in the sunburst. The radius of the arc, its distance from the root node at the centre of the sunburst, shows the taxonomic level ("superkingdom", "kingdom", etc). The length of the arc represents either the number of sequences represented at a given level, or the number of species that are found beneath the node in the tree. The weighting scheme can be changed using the sunburst controls.
In order to reduce the complexity of the representation, we reduce the number of taxonomic levels that we show. We consider only the following eight major taxonomic levels:
Colouring and labels
Segments of the tree are coloured approximately according to their superkingdom. For example, archeal branches are coloured with shades of orange, eukaryotes in shades of purple, etc. The colour assignments are shown under the sunburst controls. Where space allows, the name of the taxonomic level will be written on the arc itself.
As you move your mouse across the sunburst, the current node will be highlighted. In the top section of the controls panel we show a summary of the lineage of the currently highlighed node. If you pause over an arc, a tooltip will be shown, giving the name of the taxonomic level in the title and a summary of the number of sequences and species below that node in the tree.
Anomalies in the taxonomy tree
There are some situations that the sunburst tree cannot easily handle and for which we have work-arounds in place.
Missing taxonomic levels
Some species in the taxonomic tree may not have one or more of the main eight levels that we display. For example, Bos taurus is not assigned an order in the NCBI taxonomic tree. In such cases we mark the omitted level with, for example, "No order", in both the tooltip and the lineage summary.
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.
So that these nodes are not simply omitted from the sunburst tree, we group them together in a separate branch (or segment of the sunburst tree). Since we cannot determine the lineage for these unmapped species, we show all levels between the superkingdom and the species as "uncategorised".
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.
Too many species/sequences
For large species trees, you may see blank regions in the outer layers of the sunburst. These occur when there are large numbers of arcs to be drawn in a small space. If an arc is less than approximately one pixel wide, it will not be drawn and the space will be left blank. You may still be able to get some information about the species in that region by moving your mouse across the area, but since each arc will be very small, it will be difficult to accurately locate a particular species.
The tree shows the occurrence of this domain across different species. More...
We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.
Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.
If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.
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.
We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.
Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.
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.
You can use the tree controls to manipulate how the interactive tree is displayed:
- show/hide the summary boxes
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- expand/collapse the tree or expand it to a given depth
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Please note: for large trees this can take some time. While the tree is loading, you can safely switch away from this tab but if you browse away from the family page entirely, the tree will not be loaded.
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 AAA_17 domain has been found. There are 29 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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