Crystal structure of plant aspartic proteinase prophytepsin: inactivation and vacuolar targeting.
Ontology highlight
ABSTRACT:
SUBMITTER: Kervinen J
PROVIDER: S-EPMC1171470 | biostudies-other | 1999 Jul
REPOSITORIES: biostudies-other
Publications
Crystal structure of plant aspartic proteinase prophytepsin: inactivation and vacuolar targeting.
Kervinen J J Tobin G J GJ Costa J J Waugh D S DS Wlodawer A A Zdanov A A
The EMBO journal 19990701 14
We determined at 2.3 A resolution the crystal structure of prophytepsin, a zymogen of a barley vacuolar aspartic proteinase. In addition to the classical pepsin-like bilobal main body of phytepsin, we also traced most of the propeptide, as well as an independent plant-specific domain, never before described in structural terms. The structure revealed that, in addition to the propeptide, 13 N-terminal residues of the mature phytepsin are essential for inactivation of the enzyme. Comparison of the ...[more]
Similar Datasets
Project description:We report the crystal structure of the first prokaryotic aspartic proteinase-like domain identified in the genome of Mycobacterium tuberculosis. A search in the genomes of Mycobacterium species showed that the C-terminal domains of some of the PE family proteins contain two classic DT/SG motifs of aspartic proteinases with a low overall sequence similarity to HIV proteinase. The three-dimensional structure of one of them, Rv0977 (PE_PGRS16) of M. tuberculosis revealed the characteristic pepsin-fold and catalytic site architecture. However, the active site was completely blocked by the N-terminal His-tag. Surprisingly, the enzyme was found to be inactive even after the removal of the N-terminal His-tag. A comparison of the structure with pepsins showed significant differences in the critical substrate binding residues and in the flap tyrosine conformation that could contribute to the lack of proteolytic activity of Rv0977.
| S-EPMC3722594 | biostudies-literature
Project description:Medically important yeasts of the genus Candida secrete aspartic proteinases (Saps), which are of particular interest as virulence factors. Like Candida albicans, Candida tropicalis secretes in vitro one dominant Sap (Sapt1p) in a medium containing bovine serum albumin (BSA) as the sole source of nitrogen. Using the gene SAPT1 as a probe and under low-stringency hybridization conditions, three new closely related gene sequences, SAPT2 to SAPT4, encoding secreted proteinases were cloned from a C. tropicalis lambdaEMBL3 genomic library. All bands identified by Southern blotting of EcoRI-digested C. tropicalis genomic DNA with SAPT1 could be assigned to a specific SAP gene. Therefore, the SAPT gene family of C. tropicalis is likely to contain only four members. Interestingly, the SAPT2 and SAPT3 gene products, Sapt2p and Sapt3p, which have not yet been detected in C. tropicalis cultures in vitro, were produced as active recombinant enzymes with the methylotrophic yeast Pichia pastoris as an expression system. As expected, reverse transcriptase PCR experiments revealed a strong SAPT1 signal with RNA extracted from cells grown in BSA medium. However, a weak signal was obtained with all other SAPT genes under several conditions tested, showing that these SAPT genes could be expressed at a basic level. Together, these experiments suggest that the gene products Sapt2p, Sapt3p, and Sapt4p could be produced under conditions yet to be described in vitro or during infection.
| S-EPMC97897 | biostudies-literature
Project description:BackgroundPhytophthora species are oomycete plant pathogens with such major social and economic impact that genome sequences have been determined for Phytophthora infestans, P. sojae and P. ramorum. Pepsin-like aspartic proteinases (APs) are produced in a wide variety of species (from bacteria to humans) and contain conserved motifs and landmark residues. APs fulfil critical roles in infectious organisms and their host cells. Annotation of Phytophthora APs would provide invaluable information for studies into their roles in the physiology of Phytophthora species and interactions with their hosts.ResultsGenomes of Phytophthora infestans, P. sojae and P. ramorum contain 11-12 genes encoding APs. Nine of the original gene models in the P. infestans database and several in P. sojae and P. ramorum (three and four, respectively) were erroneous. Gene models were corrected on the basis of EST data, consistent positioning of introns between orthologues and conservation of hallmark motifs. Phylogenetic analysis resolved the Phytophthora APs into 5 clades. Of the 12 sub-families, several contained an unconventional architecture, as they either lacked a signal peptide or a propart region. Remarkably, almost all APs are predicted to be membrane-bound.ConclusionsOne of the twelve Phytophthora APs is an unprecedented fusion protein with a putative G-protein coupled receptor as the C-terminal partner. The others appear to be related to well-documented enzymes from other species, including a vacuolar enzyme that is encoded in every fungal genome sequenced to date. Unexpectedly, however, the oomycetes were found to have both active and probably-inactive forms of an AP similar to vertebrate BACE, the enzyme responsible for initiating the processing cascade that generates the Aβ peptide central to Alzheimer's Disease. The oomycetes also encode enzymes similar to plasmepsin V, a membrane-bound AP that cleaves effector proteins of the malaria parasite Plasmodium falciparum during their translocation into the host red blood cell. Since the translocation of Phytophthora effector proteins is currently a topic of intense research activity, the identification in Phytophthora of potential functional homologues of plasmepsin V would appear worthy of investigation. Indeed, elucidation of the physiological roles of the APs identified here offers areas for future study. The significant revision of gene models and detailed annotation presented here should significantly facilitate experimental design.
| S-EPMC3116508 | biostudies-literature
Project description:The possibility of using firefly luciferase as a substrate for an aspartic proteinase was explored. Several amino acid modifications to the C-terminus of the luciferase were created on the basis of the known substrate of the Arabidopsis thaliana aspartic proteinase, pro-(barley lectin). One luciferase with the sequence Arg-Asp-Gly-Val-Phe-Ala-Ala instead of the native Arg-Glu-Ile-Leu-Ile-Lys-Ala at position -15 to -9 relative to the C-terminus of native luciferase was found to possess 17% of the original luciferase activity. When this modified luciferase was incubated with the aspartic proteinase, a specific loss in activity occurred that was not observed with the original luciferase. However, both enzymes seemed very sensitive to the acidic conditions required for aspartic proteinase activity. The other versions of luciferase with different numbers of pro-(barley lectin) amino acids were not active luciferases. This provided information on the structural requirements of the C-terminal portion of the protein for luciferase activity. The luciferase proteins were also monitored during the digestion by using Western blots and some were shown to be substrates for the aspartic proteinase. Contrary to what had been expected, the modified luciferase that incorporated the pro-(barley lectin) sequences was not simply cleaved at the engineered site but at additional positions in the protein. The Arabidopsis aspartic proteinase cleaved two other standard protein substrates at many sites, suggesting that this proteinase could have a role in the degradation of proteins in addition to processing propeptides in plants.
| S-EPMC1220571 | biostudies-other
Project description:Aspartic proteinases are a well-characterized class of proteinases. In plants, all nascent aspartic proteinases possess a 100-amino-acid, plant-specific sequence (PSS) within their C-terminal lobe, presumed to possess a targeting role in vivo. In this study, the PSS domain from the Arabidopsis thaliana aspartic proteinase was inserted into porcine pepsinogen at the identical location found in nascent plant aspartic proteinases, to create a chimaeric mammalian-plant enzyme. Based on enzymic activity, this chimaeric enzyme demonstrated increases in pH stability above 6 and temperature stability above 60 degrees C compared with commercial pepsin. Differential scanning calorimetry of the chimaeric enzyme illustrated an approx. 2 degrees C increase in denaturation temperature ( T (m)), with increases in co-operativity and similar enthalpy values. Kinetic analysis indicated an increase in K (m) and decreased k (cat) compared with pepsin, but with a catalytic efficiency similar to the monomeric plant aspartic proteinase from wheat. Using oxidized insulin B-chain, the chimaeric enzyme demonstrated more restricted substrate specificity in comparison with commercial pepsin. This study highlights the use of a chimaeric enzyme strategy in order to characterize unique protein domains within enzyme families, and, for the first time, a putative structure-function role for the PSS as it pertains to plant aspartic proteinases.
| S-EPMC1223440 | biostudies-other
Project description:The squash aspartic acid proteinase inhibitor (SQAPI), a proteinaceous proteinase inhibitor from squash, is an effective inhibitor of a range of aspartic proteinases. Proteinaceous aspartic proteinase inhibitors are rare in nature. The only other example in plants probably evolved from a precursor serine proteinase inhibitor. Earlier work based on sequence homology modeling suggested SQAPI evolved from an ancestral cystatin. In this work, we determined the solution structure of SQAPI using NMR and show that SQAPI shares the same fold as a plant cystatin. The structure is characterized by a four-strand anti-parallel beta-sheet gripping an alpha-helix in an analogous manner to fingers of a hand gripping a tennis racquet. Truncation and site-specific mutagenesis revealed that the unstructured N terminus and the loop connecting beta-strands 1 and 2 are important for pepsin inhibition, but the loop connecting strands 3 and 4 is not. Using ambiguous restraints based on the mutagenesis results, SQAPI was then docked computationally to pepsin. The resulting model places the N-terminal strand of SQAPI in the S' side of the substrate binding cleft, whereas the first SQAPI loop binds on the S side of the cleft. The backbone of SQAPI does not interact with the pepsin catalytic Asp(32)-Asp(215) diad, thus avoiding cleavage. The data show that SQAPI does share homologous structural elements with cystatin and appears to retain a similar protease inhibitory mechanism despite its different target. This strongly supports our hypothesis that SQAPI evolved from an ancestral cystatin.
| S-EPMC2930701 | biostudies-literature
Project description:This study presents pioneering data concerning the human pregnancy-associated glycoprotein-Like family, identified in the genome, of the term placental transcriptome and proteome. RNA-seq allowed the identification of 1364 bp hPAG-L/pep cDNA with at least 56.5% homology with other aspartic proteinases (APs). In silico analyses revealed 388 amino acids (aa) of full-length hPAG-L polypeptide precursor, with 15 aa-signal peptide, 47 aa-blocking peptide and 326 aa-mature protein, and two Asp residues (D), specific for a catalytic cleft of the APs (VVFDTGSSNLWV91-102 and AIVDTGTSLLTG274-285). Capillary sequencing identified 9330 bp of the hPAG-L gene (Gen Bank Acc. No. KX533473), composed of nine exons and eight introns. Heterologous Western blotting revealed the presence of one dominant 60 kDa isoform of the hPAG-L amongst cellular placental proteins. Detection with anti-pPAG-P and anti-Rec pPAG2 polyclonals allowed identification of the hPAG-L proteins located within regions of chorionic villi, especially within the syncytiotrophoblast of term singleton placentas. Our novel data extend the present knowledge about the human genome, as well as placental transcriptome and proteome during term pregnancy. Presumably, this may contribute to establishing a new diagnostic tool for examination of some disturbances during human pregnancy, as well as growing interest from both scientific and clinical perspectives.
| S-EPMC5486050 | biostudies-literature
Project description:BACKGROUND: Metamorphosis is a complex, highly conserved and strictly regulated development process that involves the programmed cell death of obsolete larval organs. Here we show a novel functional role for the aspartic proteinase cathepsin D during insect metamorphosis. RESULTS: Cathepsin D of the silkworm Bombyx mori (BmCatD) was ecdysone-induced, differentially and spatially expressed in the larval fat body of the final instar and in the larval gut of pupal stage, and its expression led to programmed cell death. Furthermore, BmCatD was highly induced in the fat body of baculovirus-infected B. mori larvae, suggesting that this gene is involved in the induction of metamorphosis of host insects infected with baculovirus. RNA interference (RNAi)-mediated BmCatD knock-down inhibited programmed cell death of the larval fat body, resulting in the arrest of larval-pupal transformation. BmCatD RNAi also inhibited the programmed cell death of larval gut during pupal stage. CONCLUSION: Based on these results, we concluded that BmCatD is critically involved in the programmed cell death of the larval fat body and larval gut in silkworm metamorphosis.
| S-EPMC1629011 | biostudies-literature
Project description:Aspartic proteinases (AP) form a multigenic group widely distributed in various organisms and includes pepsins (pep), cathepsins D and E, pregnancy associated glycoproteins (PAGs) as well as plant, fungal, and retroviral proteinases. This study describes the transcript identification and expression localization of the AP within the discoid placenta of the Castor fiber. We identified 1257 bp of the AP cDNA sequence, encoding 391 amino acids (aa) of the polypeptide precursor composed of 16 aa signal peptide, 46 aa pro-piece, and 329 aa of the mature protein. Within the AP precursor, one site of potential N-glycosylation (NPS119–121) and two Asp residues (D) specific for the catalytic cleft of AP were identified (VLFDTGSSNLWV91–102 and GIVDTGTSLLTV277–288). The highest homology of the identified placental AP nucleotide and aa sequence was to mouse pepsinogen C (75.8% and 70.1%, respectively). Identified AP also shared high homology with other superfamily members: PAGs, cathepsins, and napsins. The AP identified in this study was named as pepsinogen/PAG-Like (pep/PAG-L). Diversified pep/PAG-L protein profiles with a dominant 58 kDa isoform were identified. Immune reactive signals of the pep/PAG-L were localized within the trophectodermal cells of the beaver placenta. This is the first report describing the placental AP (pep/PAG-L) in the C. fiber.
| S-EPMC5979379 | biostudies-literature
Project description:Many plant aspartic proteases contain an additional sequence of ~100 amino acids termed the plant-specific insert, which is involved in host defense and vacuolar targeting. Similar to all saposin-like proteins, the plant-specific insert functions via protein-membrane interactions; however, the structural basis for such interactions has not been studied, and the nature of plant-specific insert-mediated membrane disruption has not been characterized. In the present study, the crystal structure of the saposin-like domain of potato aspartic protease was resolved at a resolution of 1.9 Å, revealing an open V-shaped configuration similar to the open structure of human saposin C. Notably, vesicle disruption activity followed Michaelis-Menten-like kinetics, a finding not previously reported for saposin-like proteins including plant-specific inserts. Circular dichroism data suggested that secondary structure was pH-dependent in a fashion similar to influenza A hemagglutinin fusion peptide. Membrane effects characterized by atomic force microscopy and light scattering indicated bilayer solubilization as well as fusogenic activity. Taken together, the present study is the first report to elucidate the membrane interaction mechanism of plant saposin-like domains whereby pH-dependent membrane interactions resulted in bilayer fusogenic activity that probably arose from a viral type pH-dependent helix-kink-helix motif at the plant-specific insert N terminus.
| S-EPMC3151071 | biostudies-literature