Summary: C-terminal AAA-associated domain

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Wikipedia: AAA proteins
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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.^[1]

Identifiers

Symbol

AAA

Pfam clan

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe
PDBsum	structure summary

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.^[2]^[3] These proteins are involved in a range of processes, including DNA replication, protein degradation, membrane fusion, microtubule severing, peroxisome biogenesis, signal transduction and the regulation of gene expression.

The characteristic of AAA proteins is the coupling of chemical energy by ATPase, provided by ATP hydrolysis, to mechanical force exerted on some macromolecular substrate. This usually requires a conformational change in the AAA protein in question.

AAA ATPases assemble into oligomeric assemblies (often 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.^[4]

Members of the AAA family are found in all organisms and they are essential for many cellular functions.

One type of AAA proteins are AAA proteases, where the energy from ATP hydrolysis is used to translocate a protein inside the protease for degradation.

AAA-type ATPases constitute a large family of enzymes. AAA proteins are characterised by the presence of 200-250 amino-acid ATP-binding domains that contain Walker A and Walker B motifs. AAA proteins themselves belong to the superfamily of P-loop NTPases.

[edit] Domain structure of AAA-type ATPases

All AAA+ proteins have a mixed alpha/beta domain that binds and hydrolyzes nucleotide. Most AAA+ proteins have a second domain that comprises the AAA+ module: an all alpha-helical domain, often called the lid domain, that is C-terminal of the alpha/beta domain. 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.

[edit] From AAA to AAA+

The classical AAA family has been expanded by inclusion of a number of more distantly related cellular regulators and termed AAA+ family of ATPases (112). AAA+ proteins are involved in protein degradation, membrane fusion, DNA replication, microtubule dynamics, intracellular transport, flagellar and ciliary beating, disassembly of protein complexes and protein aggregates.

[edit] AAAs are often Hexamers

The physiologically active form of these enzymes is often a homo-hexamer. The hexameric enzymes have an overall shape that resembles a ring with a central pore that might 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.

[edit] Prokaryotic AAAs

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.

[edit] AAAs in protein transport

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.

[edit] 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 âclass Eâ 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.

[edit] 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;

[edit] Further reading

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. //www.ncbi.nlm.nih.gov/pmc/articles/PMC2643927/.
Snider J, Houry WA (February 2008). "AAA+ proteins: diversity in function, similarity in structure". Biochem. Soc. Trans. 36 (Pt 1): 72â7. doi:10.1042/BST0360072. PMID 18208389.
Tucker PA, Sallai L (December 2007). "The AAA+ superfamily--a myriad of motions". Curr. Opin. Struct. Biol. 17 (6): 641â52. doi:10.1016/j.sbi.2007.09.012. PMID 18023171.
White SR, Lauring B (December 2007). "AAA+ ATPases: achieving diversity of function with conserved machinery". Traffic 8 (12): 1657â67. doi:10.1111/j.1600-0854.2007.00642.x. PMID 17897320.
Hanson PI, Whiteheart SW (July 2005). "AAA+ proteins: have engine, will work". Nat. Rev. Mol. Cell Biol. 6 (7): 519â29. doi:10.1038/nrm1684. PMID 16072036.

[edit] References

^ Yu RC, Hanson PI, Jahn R, BrÃ¼nger AT (September 1998). "Structure of the ATP-dependent oligomerization domain of N-ethylmaleimide sensitive factor complexed with ATP". Nat. Struct. Biol. 5 (9): 803â11. 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 (1â2): 11â31. doi:10.1016/j.jsb.2003.10.010. PMID 15037234.
^ Lupas AN, Frickey T (2004). "Phylogenetic analysis of AAA proteins". J. Struct. Biol. 146 (1â2): 2â10. doi:10.1016/j.jsb.2003.11.020. PMID 15037233.
^ Smith DM, Benaroudj N, Goldberg A (2006). "Proteasomes and their associated ATPases: A destructive combination". J. Struct. Biol. 156 (1): 72â83. doi:10.1016/j.jsb.2006.04.012. PMID 16919475.

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C-terminal AAA-associated domain Provide feedback

This had been thought to be an ATPase domain of ABC-transporter proteins. However, only one member has any trans-membrane regions. It is associated with an upstream ATP-binding cassette family, PF00005.

External database links

PANDIT:	PF09821
Pseudofam:	PF09821
SYSTERS:	AAA_assoc_C

This tab holds annotation information from the InterPro database.

InterPro entry IPR018632

Members of this family are found in various prokaryotic ABC transporters, predominantly involved in nitrate, sulphonate and bicarbonate translocation.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Alignments

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.

Alignment types

We make a range of alignments for each Pfam-A family:

seed: the curated alignment from which the HMM for the family is built
full: the alignment generated by searching the sequence database using the HMM
RP15/RP35/RP55/RP75: Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
NCBI: alignment generated by searching the NCBI sequence database using the family HMM
meta: alignment generated by searching the metagenomics sequence database using the family HMM

Viewing

You can see the alignments as HTML or in three different sequence viewers:

jalview: a Java applet developed at the University of Dundee. You will need Java installed before running jalview
HTML: an HTML page showing the whole alignment.Please note: full Pfam alignments can be very large. These HTML views are extremely large and often cause problems for browsers. Please use either jalview or the Pfam viewer if you have trouble viewing the HTML version
PP/Heatmap: an HTML-based representation of the alignment, coloured according to the posterior-probability (PP) values from the HMM. As for the standard HTML view, heatmap alignments can also be very large and slow to render.
Pfam viewer: an HTML-based viewer that uses DAS to retrieve alignment fragments on request

Reformatting

You can download (or view in your browser) a text representation of a Pfam alignment in various formats:

Selex
Stockholm
FASTA
MSF

You can also change the order in which sequences are listed in the alignment, change how insertions are represented, alter the characters that are used to represent gaps in sequences and, finally, choose whether to download the alignment or to view it in your browser directly.

Downloading

You may find that large alignments cause problems for the viewers and the reformatting tool, so we also provide all alignments in Stockholm format. You can download either the plain text alignment, or a gzipped version of it.

View options

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.

	Seed (49)	Full (413)	Representative proteomes				NCBI (349)	Meta (21)
	Seed (49)	Full (413)	RP15 (38)	RP35 (81)	RP55 (117)	RP75 (152)	NCBI (349)	Meta (21)
Jalview	View	View	View	View	View	View	View	View
HTML	View	View	View	View	View	View
PP/heatmap	₁	View	View	View	View	View
Pfam viewer	View	View

¹Cannot generate PP/Heatmap alignments for seeds; no PP data available

Key: available, not generated, — not available.

Format an alignment

	Seed (49)	Full (413)	Representative proteomes				NCBI (349)	Meta (21)
	Seed (49)	Full (413)	RP15 (38)	RP35 (81)	RP55 (117)	RP75 (152)	NCBI (349)	Meta (21)
Alignment:
Format:
Order:	Tree Alphabetical
Sequence:	Inserts lower case All upper case
Gaps:
Download/view:	Download View

Download options

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.

	Seed (49)	Full (413)	Representative proteomes				NCBI (349)	Meta (21)
	Seed (49)	Full (413)	RP15 (38)	RP35 (81)	RP55 (117)	RP75 (152)	NCBI (349)	Meta (21)
Raw Stockholm	Download	Download	Download	Download	Download	Download	Download	Download
Gzipped	Download	Download	Download	Download	Download	Download	Download	Download

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

External links

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 logo

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...

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.

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.

Curation

Seed source:

COGs (COG4754)

Previous IDs:

ABC_transp; AAA_36;

Type:

Domain

Author:

COGs, Finn RD, Sammut SJ

Number in seed:

49

Number in full:

413

Average length of the domain:

118.50 aa

Average identity of full alignment:

38 %

Average coverage of the sequence by the domain:

29.96 %

HMM information

HMM build commands:

build method: hmmbuild -o /dev/null HMM SEED

search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq

Model details:

Parameter	Sequence	Domain
Gathering cut-off	21.3	21.3
Trusted cut-off	21.3	21.4
Noise cut-off	21.2	20.8

Model length:

120

Family (HMM) version:

4

Download:

download the raw HMM for this family

Species distribution

Sunburst
Tree

Sunburst controls

Show

This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. 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:

superkingdom
kingdom
phylum
class
order
family
genus
species

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".

Sub-species

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.

Loading sunburst data...

Tree controls

Hide

The tree shows the occurrence of this domain across different species. More...

Species trees

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.

Interactive tree

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
highlight species that are represented in the seed alignment
expand/collapse the tree or expand it to a given depth
select a sub-tree or a set of species within the tree and view them graphically or as an alignment
save a plain text representation of the tree

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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.

Archea	Eukaryota
Bacteria	Other sequences
Viruses	Unclassified
Viroids	Unclassified sequence

Family: AAA_assoc_C (PF09821)

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