Cellular and retroviral pepsin-like aspartate proteases; This family includes both cellular and retroviral pepsin-like aspartate proteases. The cellular pepsin and pepsin-like enzymes are twice as long as their retroviral counterparts. The cellular pepsin-like aspartic proteases are found in mammals, plants, fungi and bacteria. These well known and extensively characterized enzymes include pepsins, chymosin, rennin, cathepsins, and fungal aspartic proteases. Several have long been known to be medically (rennin, cathepsin D and E, pepsin) or commercially (chymosin) important. The eukaryotic pepsin-like proteases contain two domains possessing similar topological features. The N- and C-terminal domains, although structurally related by a 2-fold axis, have only limited sequence homology except in the vicinity of the active site. This suggests that the enzymes evolved by an ancient duplication event. The eukaryotic pepsin-like proteases have two active site ASP residues with each N- and C-terminal lobe contributing one residue. While the fungal and mammalian pepsins are bilobal proteins, retropepsins function as dimers and the monomer resembles structure of the N- or C-terminal domains of eukaryotic enzyme. The active site motif (Asp-Thr/Ser-Gly-Ser) is conserved between the retroviral and eukaryotic proteases and between the N-and C-terminal of eukaryotic pepsin-like proteases. The retropepsin-like family includes pepsin-like aspartate proteases from retroviruses, retrotransposons and retroelements; as well as eukaryotic DNA-damage-inducible proteins (DDIs), and bacterial aspartate peptidases. Retropepsin is synthesized as part of the POL polyprotein that contains an aspartyl-protease, a reverse transcriptase, RNase H, and an integrase. The POL polyprotein undergoes specific enzymatic cleavage to yield the mature proteins. This family of aspartate proteases is classified by MEROPS as the peptidase family A1 (pepsin A) and A2 (retropepsin family).

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                ....*....|....*....|....*....|....*.
gi 1723987   65 GVYVVKMEIGTPPQTVYLQLDTGSSDMIVNNADIAY 100
Cdd:cd05474   1 TYYSAELSVGTPPQKVTVLLDTGSSDLWVPDFSISY 36

SAPs, pepsin-like proteinases secreted from pathogens to degrade host proteins; SAPs (Secreted aspartic proteinases) are secreted from a group of pathogenic fungi, predominantly Candida species. They are secreted from the pathogen to degrade host proteins. SAP is one of the most significant extracellular hydrolytic enzymes produced by C. albicans. SAP proteins, encoded by a family of 10 SAP genes. All 10 SAP genes of C. albicans encode preproenzymes, approximately 60 amino acid longer than the mature enzyme, which are processed when transported via the secretory pathway. The mature enzymes contain sequence motifs typical for all aspartyl proteinases, including the two conserved aspartate residues other active site and conserved cysteine residues implicated in the maintenance of the three-dimensional structure. Most Sap proteins contain putative N-glycosylation sites, but it remains to be determined which Sap proteins are glycosylated. This family of aspartate proteases is classified by MEROPS as the peptidase family A1 (pepsin A, clan AA). The overall structure of Sap protein conforms to the classical aspartic proteinase fold typified by pepsin. SAP is a bilobal enzyme, each lobe contributing a catalytic Asp residue, with an extended active site cleft localized between the two lobes of the molecule. One lobe may be evolved from the other through ancient gene-duplication event. More recently evolved enzymes have similar three-dimensional structures, however their amino acid sequences are more divergent except for the conserved catalytic site motif. This family of aspartate proteases is classified by MEROPS as the peptidase family A1 (pepsin A, clan AA).

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                ....*....|....*....|....*....|....*.
gi 1723987   65 GVYVVKMEIGTPPQTVYLQLDTGSSDMIVNNADIAY 100
Cdd:cd05474   1 TYYSAELSVGTPPQKVTVLLDTGSSDLWVPDFSISY 36

SAPs, pepsin-like proteinases secreted from pathogens to degrade host proteins; SAPs (Secreted aspartic proteinases) are secreted from a group of pathogenic fungi, predominantly Candida species. They are secreted from the pathogen to degrade host proteins. SAP is one of the most significant extracellular hydrolytic enzymes produced by C. albicans. SAP proteins, encoded by a family of 10 SAP genes. All 10 SAP genes of C. albicans encode preproenzymes, approximately 60 amino acid longer than the mature enzyme, which are processed when transported via the secretory pathway. The mature enzymes contain sequence motifs typical for all aspartyl proteinases, including the two conserved aspartate residues other active site and conserved cysteine residues implicated in the maintenance of the three-dimensional structure. Most Sap proteins contain putative N-glycosylation sites, but it remains to be determined which Sap proteins are glycosylated. This family of aspartate proteases is classified by MEROPS as the peptidase family A1 (pepsin A, clan AA). The overall structure of Sap protein conforms to the classical aspartic proteinase fold typified by pepsin. SAP is a bilobal enzyme, each lobe contributing a catalytic Asp residue, with an extended active site cleft localized between the two lobes of the molecule. One lobe may be evolved from the other through ancient gene-duplication event. More recently evolved enzymes have similar three-dimensional structures, however their amino acid sequences are more divergent except for the conserved catalytic site motif. This family of aspartate proteases is classified by MEROPS as the peptidase family A1 (pepsin A, clan AA).

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                ....*....|....*....|....*....|....*.
gi 1723987   65 GVYVVKMEIGTPPQTVYLQLDTGSSDMIVNNADIAY 100
Cdd:cd05474   1 TYYSAELSVGTPPQKVTVLLDTGSSDLWVPDFSISY 36

Aspergillopepsin_like, aspartic proteases of fungal origin; The members of this family are aspartic proteases of fungal origin, including aspergillopepsin, rhizopuspepsin, endothiapepsin, and rodosporapepsin. The various fungal species in this family may be the most economically important genus of fungi. They may serve as virulence factors or as industrial aids. For example, Aspergillopepsin from A. fumigatus is involved in invasive aspergillosis owing to its elastolytic activity and Aspergillopepsins from the mold A. saitoi are used in fermentation industry. Aspartic proteinases are a group of proteolytic enzymes in which the scissile peptide bond is attacked by a nucleophilic water molecule activated by two aspartic residues in a DT(S)G motif at the active site. They have a similar fold composed of two beta-barrel domains. Between the N-terminal and C-terminal domains, each of which contributes one catalytic aspartic residue, there is an extended active-site cleft capable of interacting with multiple residues of a substrate. Although members of the aspartic protease family of enzymes have very similar three-dimensional structures and catalytic mechanisms, each has unique substrate specificity. The members of this family has an optimal acidic pH (5.5) and cleaves protein substrates with similar specificity to that of porcine pepsin A, preferring hydrophobic residues at P1 and P1' in the cleave site. This family of aspartate proteases is classified by MEROPS as the peptidase family A1 (pepsin A, clan AA).

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gi 1723987   67 YVVKMEIGTPPQTVYLQLDTGSSDMIV 93
Cdd:cd06097   1 YLTPVKIGTPPQTLNLDLDTGSSDLWV 27

Xylanase inhibitor N-terminal; The N- and C-termini of the members of this family are jointly necessary for creating the catalytic pocket necessary for cleaving xylanase. Phytopathogens produce xylanase that destroys plant cells, so its destruction through proteolysis is vital for plant-survival.

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                  ....*....|....*....|...
gi 1723987     67 YVVKMEIGTPPQTVYLQLDTGSS 89
Cdd:pfam14543   1 YLVTISIGTPPVPFFLVVDTGSD 23

Beta-secretase, aspartic-acid protease important in the pathogenesis of Alzheimer's disease; Beta-secretase also called BACE (beta-site of APP cleaving enzyme) or memapsin-2. Beta-secretase is an aspartic-acid protease important in the pathogenesis of Alzheimer's disease, and in the formation of myelin sheaths in peripheral nerve cells. It cleaves amyloid precursor protein (APP) to reveal the N-terminus of the beta-amyloid peptides. The beta-amyloid peptides are the major components of the amyloid plaques formed in the brain of patients with Alzheimer's disease (AD). Since BACE mediates one of the cleavages responsible for generation of AD, it is regarded as a potential target for pharmacological intervention in AD. Beta-secretase is a member of pepsin family of aspartic proteases. Same as other aspartic proteases, beta-secretase is a bilobal enzyme, each lobe contributing a catalytic Asp residue, with an extended active site cleft localized between the two lobes of the molecule. The N- and C-terminal domains, although structurally related by a 2-fold axis, have only limited sequence homology except the vicinity of the active site. This suggests that the enzymes evolved by an ancient duplication event. The enzymes specifically cleave bonds in peptides which have at least six residues in length with hydrophobic residues in both the P1 and P1' positions. The active site is located at the groove formed by the two lobes, with an extended loop projecting over the cleft to form an 11-residue flap, which encloses substrates and inhibitors in the active site. Specificity is determined by nearest-neighbor hydrophobic residues surrounding the catalytic aspartates, and by three residues in the flap. The enzymes are mostly secreted from cells as inactive proenzymes that activate autocatalytically at acidic pH. This family of aspartate proteases is classified by MEROPS as the peptidase family A1 (pepsin A, clan AA).

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gi 1723987   67 YVVKMEIGTPPQTVYLQLDTGSSDMIV 93
Cdd:cd05473   4 YYIEMLIGTPPQKLNILVDTGSSNFAV 30