Summary: Aspartyl protease
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Aspartate protease Edit Wikipedia article
|Eukaryotic aspartyl protease|
Structures of native and inhibited forms of human cathepsin D.
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. More recently, aspartic endopeptidases associated with the processing of bacterial type 4 prepilin and archaean preflagellin have been described.
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.
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. 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.
Pepstatin is an inhibitor of aspartate proteases.
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.
There are six catalytic types of protease: aspartic acid, cysteine, glutamic acid, 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).
crystal and molecular structures of human progastricsin at 1.62 angstroms resolution
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.
- Cathepsin D
- Cathepsin E
- Chymosin (or "rennin")
Human proteins containing this domain
- 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
- 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): 6796–800. doi:10.1073/pnas.90.14.6796. PMC 47019. PMID 8393577.
- Szecsi PB (1992). "The aspartic proteases". Scand. J. Clin. Lab. In vest. Suppl. 210: 5–22. 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): 1502–10. 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): 167–91. 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): 1339–1347. doi:10.1046/j.1365-2958.2003.03758.x. PMID 14622420.
- 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): 7009–13. doi:10.1073/pnas.84.20.7009. PMC 299218. PMID 3313384.
- Brik A, Wong CH (2003). "HIV-1 protease: mechanism and drug discovery". Org. Biomol. Chem. 1 (1): 5–14. 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): 1–25. 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): 671–92. doi:10.1016/0022-2836(91)90664-R. PMID 2056534.
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
|Similarity to PfamA using HHSearch:||RVP Peptidase_A3 DUF1758 RVP_2 Asp_protease Peptidase_A2B gag-asp_proteas|
External database links
This tab holds annotation information from the InterPro database.
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- 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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This clan contains aspartic peptidases, including the pepsins and retropepsins. These enzymes contains a catalytic dyad composed of two aspartates. In the retropepsins one is provided by each copy of a homodimeric protein, whereas in the pepsin-like peptidases these aspartates come from a single protein composed of two duplicated domains.
The clan 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
We make a range of alignments for each Pfam-A family:
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- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the NCBI sequence database using the family HMM
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Curation and family details
|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 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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