Summary: Aspartyl protease

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Wikipedia: Aspartate protease
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Aspartate protease Edit Wikipedia article

Eukaryotic aspartyl protease

Structures of native and inhibited forms of human cathepsin D.^[1]

Identifiers

Symbol

Asp

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

Aspartic proteases are a family of protease enzymes that use an aspartate residue for catalysis of their peptide substrates. In general, they have two highly-conserved aspartates in the active site and are optimally active at acidic pH. Nearly all known aspartyl proteases are inhibited by pepstatin.

Aspartic endopeptidases EC 3.4.23. of vertebrate, fungal and retroviral origin have been characterised.^[2] More recently, aspartic endopeptidases associated with the processing of bacterial type 4 prepilin^[3] and archaean preflagellin have been described.^[4]^[5]

Eukaryotic aspartic proteases include pepsins, cathepsins, and renins. They have a two-domain structure, arising from ancestral duplication. Retroviral and retrotransposon proteases (Pfam PF00077) are much smaller and appear to be homologous to a single domain of the eukaryotic aspartyl proteases. Each domain contributes a catalytic Asp residue, with an extended active site cleft localized between the two lobes of the molecule. One lobe has probably evolved from the other through a gene duplication event in the distant past. In modern-day enzymes, although the three-dimensional structures are very similar, the amino acid sequences are more divergent, except for the catalytic site motif, which is very conserved. The presence and position of disulfide bridges are other conserved features of aspartic peptidases.

[edit] Catalytic Mechanism

Aspartyl proteases are a highly specific family of proteases - they tend to cleave dipeptide bonds that have hydrophobic residues as well as a beta-methylene group. Unlike the closely related serine proteases these proteases do not form a covalent intermediate during cleavage.

While a number of different mechanisms for aspartyl proteases have been proposed, the most widely accepted is a general acid-base mechanism involving coordination of a water molecule between the two highly-conserved aspartate residues.^[6]^[7] One aspartate activates the water by abstracting a proton, enabling the water to attack the carbonyl carbon of the substrate scissile bond, generating a tetrahedral oxyanion intermediate. Rearrangement of this intermediate leads to protonation of the scissile amide.

Proposed mechanism of peptide cleavage by aspartyl proteases.^[6]

[edit] Inhibition

Pepstatin is an inhibitor of aspartate proteases.

[edit] Evolution

All aspartate proteases have a highly conserved sequence of Asp-Thr-Gly. In general, with the exception of HIV - a dimer of two identical subunits - these enzymes are monomeric enzymes consisting of two domains. Because of this organisation, it is thought that these domains may have arisen through ancestral gene duplication.

[edit] Classification

There are six catalytic types of protease: aspartic acid, cysteine, glutamic, metallo, serine and threonine.

The aspartase proteases are divided into four families.

Family A01 (Pepsin family)
Family A02
Family A22
Family Ax1

A fifth family has also been described. This family is derived from the prolactin-induced protein/gross cystic disease fluid protein-15 (PIP/GCDFP15).

[edit] Propeptide

A1_Propeptide

crystal and molecular structures of human progastricsin at 1.62 angstroms resolution

Identifiers

Symbol

A1_Propeptide

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

Many eukaryotic aspartic endopeptidases (MEROPS peptidase family A1) are synthesised with signal and propeptides. The animal pepsin-like endopeptidase propeptides form a distinct family of propeptides, which contain a conserved motif approximately 30 residues long. In pepsinogen A, the first 11 residues of the mature pepsin sequence are displaced by residues of the propeptide. The propeptide contains two helices that block the active site cleft, in particular the conserved Asp11 residue, in pepsin, hydrogen bonds to a conserved Arg residue in the propeptide. This hydrogen bond stabilises the propeptide conformation and is probably responsible for triggering the conversion of pepsinogen to pepsin under acidic conditions.^[8]^[9]

[edit] Examples

[edit] Human

[edit] Human proteins containing this domain

BACE1; BACE2; CTSD; CTSE; NAPSA; PGA5; PGC; REN;

[edit] Other organisms

HIV-1 protease - a major drug-target for treatment of HIV

[edit] External links

The MEROPS online database for peptidases and their inhibitors: Aspartic Peptidases
Aspartic Endopeptidases at the US National Library of Medicine Medical Subject Headings (MeSH)
MEROPS family A1

[edit] See also

The Proteolysis Map

[edit] References

^ Baldwin ET, Bhat TN, Gulnik S, et al. (July 1993). "Crystal structures of native and inhibited forms of human cathepsin D: implications for lysosomal targeting and drug design". Proc. Natl. Acad. Sci. U.S.A. 90 (14): 6796â800. doi:10.1073/pnas.90.14.6796. PMC 47019. PMID 8393577. //www.ncbi.nlm.nih.gov/pmc/articles/PMC47019/.
^ Szecsi PB (1992). "The aspartic proteases". Scand. J. Clin. Lab. In vest. Suppl. 210: 5â22. doi:10.3109/00365519209104650. PMID 1455179.
^ Taylor R K, LaPointe CF (2000). "The type 4 prepilin peptidases comprise a novel family of aspartic acid proteases". J. Biol. Chem. 275 (2): 1502â10. doi:10.1074/jbc.275.2.1502. PMID 10625704.
^ Jarrell KF, Ng SY, Chaban B (2006). "Archaeal flagella, bacterial flagella and type IV pili: a comparison of genes and posttranslational modifications". J. Mol. Microbiol. Bio technol. 11 (3): 167â91. doi:10.1159/000094053. PMID 16983194.
^ Jarrell KF, Bardy SL (2003). "Cleavage of preflagellins by an aspartic acid signal peptidase is essential for flagellation in the archaeon Methanococcus voltae". Mol. Microbiol. 50 (4): 1339â1347. doi:10.1046/j.1365-2958.2003.03758.x. PMID 14622420.
^ ^a ^b Suguna K, Padlan EA, Smith CW, Carlson WD, Davies DR (1987). "Binding of a reduced peptide inhibitor to the aspartic proteinase from Rhizopus chinensis: implications for a mechanism of action". Proc. Natl. Acad. Sci. U.S.A. 84 (20): 7009â13. doi:10.1073/pnas.84.20.7009. PMC 299218. PMID 3313384. //www.ncbi.nlm.nih.gov/pmc/articles/PMC299218/.
^ Brik A, Wong CH (2003). "HIV-1 protease: mechanism and drug discovery". Org. Biomol. Chem. 1 (1): 5â14. doi:10.1039/b208248a. PMID 12929379.
^ Hartsuck JA, Koelsch G, Remington SJ (May 1992). "The high-resolution crystal structure of porcine pepsinogen". Proteins 13 (1): 1â25. doi:10.1002/prot.340130102. PMID 1594574.
^ Sielecki AR, Fujinaga M, Read RJ, James MN (June 1991). "Refined structure of porcine pepsinogen at 1.8 A resolution". J. Mol. Biol. 219 (4): 671â92. doi:10.1016/0022-2836(91)90664-R. PMID 2056534.

This article incorporates text from the public domain Pfam and InterPro IPR012848

Hydrolase: proteases (EC 3.4)

3.4.11-19: Exopeptidase

3.4.11	Aminopeptidase Alanine Arginyl Aspartyl Cystinyl Leucyl Glutamyl Methionyl 1 2 O

3.4.13	Dipeptidase 1 2 3

3.4.14	Dipeptidyl peptidase Cathepsin C Dipeptidyl peptidase-4 Tripeptidyl peptidase Tripeptidyl peptidase I Tripeptidyl peptidase II

3.4.15	Angiotensin-converting enzyme

3.4.16	Serine type carboxypeptidases: Cathepsin A DD-transpeptidase

3.4.17	Metallocarboxypeptidases: Carboxypeptidase A A2 B C E Glutamate II

Other/ungrouped	Metalloexopeptidase

3.4.21-24: Endopeptidase

Other/ungrouped: Amyloid precursor protein secretase

3.4.99: Unknown

Staphylokinase

B
enzm
1.1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 10
- 11
- 13
- 14
- 15-18
2.1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
2.7.10
2.7.11-12
3.1
- - 3.1.3.48
- 2
- 3
- 4
  - 3.4.21
- 5
- 6
- 7
- 22
- 23
- 24
4.1
- 2
- 3
- 4
- 5
- 6
5.1
- 2
- 3
- 4
- 99
6.1-3
- 4
- 5-6

Proteases: aspartic acid proteases (EC 3.4.23)

Vertebrate

Pathogenic

Plant

Nepenthesin

Cathepsin

D
E

B
enzm
1.1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 10
- 11
- 13
- 14
- 15-18
2.1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
2.7.10
2.7.11-12
3.1
- - 3.1.3.48
- 2
- 3
- 4
  - 3.4.21
- 5
- 6
- 7
- 22
- 23
- 24
4.1
- 2
- 3
- 4
- 5
- 6
5.1
- 2
- 3
- 4
- 99
6.1-3
- 4
- 5-6

This article incorporates text from the public domain Pfam and InterPro IPR000036

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Aspartyl protease Provide feedback

This family consists of predicted aspartic proteases, typically from 180 to 230 amino acids in length, in MEROPS clan AA. This model describes the well-conserved 121-residue C-terminal region. The poorly conserved, variable length N-terminal region usually contains a predicted transmembrane helix.

Internal database links

SCOOP:	gag-asp_proteas
Similarity to PfamA using HHSearch:	RVP Peptidase_A3 DUF1758 RVP_2 Asp_protease Peptidase_A2B gag-asp_proteas

External database links

MEROPS:	A28 A32
PANDIT:	PF13650
Pseudofam:	PF13650
SYSTERS:	Asp_protease_2

This tab holds annotation information from the InterPro database.

No InterPro data for this Pfam family.

Domain organisation

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

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Pfam Clan

This family is a member of clan Peptidase_AA (CL0129), which contains the following 14 members:

Asp Asp_protease Asp_protease_2 DUF1758 gag-asp_proteas Peptidase_A2B Peptidase_A2E Peptidase_A3 RVP RVP_2 Spuma_A9PTase TAXi_C TAXi_N Zn_protease

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 (300)	Full (2359)	Representative proteomes				NCBI (4331)	Meta (281)
	Seed (300)	Full (2359)	RP15 (480)	RP35 (794)	RP55 (1052)	RP75 (1248)	NCBI (4331)	Meta (281)
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 (300)	Full (2359)	Representative proteomes				NCBI (4331)	Meta (281)
	Seed (300)	Full (2359)	RP15 (480)	RP35 (794)	RP55 (1052)	RP75 (1248)	NCBI (4331)	Meta (281)
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 (300)	Full (2359)	Representative proteomes				NCBI (4331)	Meta (281)
	Seed (300)	Full (2359)	RP15 (480)	RP35 (794)	RP55 (1052)	RP75 (1248)	NCBI (4331)	Meta (281)
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:

Jackhmmer:C6QGC6

Previous IDs:

none

Type:

Domain

Author:

Coggill P

Number in seed:

300

Number in full:

2359

Average length of the domain:

91.40 aa

Average identity of full alignment:

19 %

Average coverage of the sequence by the domain:

17.90 %

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	24.0	24.0
Trusted cut-off	24.0	24.0
Noise cut-off	23.9	23.9

Model length:

90

Family (HMM) version:

1

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.

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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
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Archea	Eukaryota
Bacteria	Other sequences
Viruses	Unclassified
Viroids	Unclassified sequence

Family: Asp_protease_2 (PF13650)

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