Showing papers on "Cysteine protease published in 2011"
TL;DR: In this article, the function and regulation of AtMCP2d, the predominant and constitutively expressed member of type II MCPs, in stress-inducible PCD was investigated.
Abstract: Cysteine proteases such as caspases play important roles in programmed cell death (PCD) of metazoans. Plant metacaspases (MCPs), a family of cysteine proteases structurally related to caspases, have been hypothesized to be ancestors of metazoan caspases, despite their different substrate specificity. Arabidopsis thaliana contains six type II MCP genes (AtMCP2a-f). Whether and how these individual members are involved in controlling PCD in plants remains largely unknown. Here we investigated the function and regulation of AtMCP2d, the predominant and constitutively expressed member of type II MCPs, in stress-inducible PCD. Two AtMCP2d mutants (mcp2d-1 and mcp2d-3) exhibited reduced sensitivity to PCD-inducing mycotoxin fumonisin B1 as well as oxidative stress inducers, whereas AtMCP2d over-expressors were more sensitive to these agents, and exhibited accelerated cell-death progression. We found that AtMCP2d exclusively localizes to the cytosol, and its accumulation and self-processing patterns were age-dependent in leaves. Importantly, active proteolytic processing of AtMCP2d proteins dependent on its catalytic activity was observed in mature leaves during mycotoxin-induced cell death. We also found that mcp2d-1 leaves exhibited reduced cell death in response to Pseudomonas syringae carrying avirulent gene avrRpt2, and that self-processing of AtMCP2d was also detected in wild-type leaves in response to this pathogen. Furthermore, increases in processed AtMCP2d proteins were found to correlate with conditional cell-death induction in two lesion-mimic mutants (cpr22 and ssi4) that exhibit spontaneous cell-death phenotypes. Taken together, our data strongly suggest that AtMCP2d plays a positive regulatory role in biotic and abiotic stress-induced PCD.
141 citations
TL;DR: Evaluation of the feasibility of cathepsins as a diagnostic tool has revealed that the serum cathepsypsins S and L and the endogenous inhibitor cystatin C hold promise as biomarkers of coronary artery disease and aneurysm formation.
Abstract: Atherosclerosis-based vascular disease is an inflammatory disease characterized by extensive remodeling of the extracellular matrix architecture of the arterial wall. Although matrix metalloproteinases and serine proteases participate in these pathological events, the discovery of cysteine protease cathepsins, such as cathepsins K, S, L, and B, and cystatin C, and their tissue distribution has suggested that at least some of them participate in cardiovascular disease. Studies on vascular cells have shown that atherosclerosis-associated inflammatory cytokines augment cysteinyl cathepsin expression and activity. Novel insight into cathepsin functions has been made possible by the generation and in-depth analysis of knockout and transgenic mice. These studies have provided direct evidence implicating cathepsins in atherosclerosis-based vascular disease through the activation, liberation, and modification of angiogenic growth factors, cytokines, and proteases associated with lipid metabolism, cell events (migration, invasion, proliferation, and apoptosis), angiogenesis, and matrix protein remodeling. Furthermore, evaluation of the feasibility of cathepsins as a diagnostic tool has revealed that the serum cathepsins S and L and the endogenous inhibitor cystatin C hold promise as biomarkers of coronary artery disease and aneurysm formation. The goal of this review is to summarize the available information regarding the mechanistic contributions of cathepsins in atherosclerosis-based vascular disease.
132 citations
TL;DR: Cysteine proteases of malaria parasites have demonstrated potent antimalarial effects and the optimization and testing of falcipain inhibitor antimalarials is underway, andGene disruption studies suggested that SERA-5 andSERA-6 are essential.
Abstract: A number of cysteine proteases of malaria parasites have been described and many more are suggested by analysis of the Plasmodium falciparum genome sequence. The best characterized of these proteases are the falcipains, a family of four papain-family enzymes. Falcipain-2 and falcipain-3 act in concert with other proteases to hydrolyze host erythrocyte hemoglobin in the parasite food vacuole. Disruption of the falcipain-2 gene led to a transient block in hemoglobin hydrolysis and parasites with increased sensitivity to protease inhibitors. Disruption of the falcipain-3 gene was not possible, strongly suggesting that this protease is essential for erythrocytic parasites. Disruption of the falcipain-1 gene did not alter development in erythrocytes, but led to decreased production of oocysts in mosquitoes. other papain-family proteases predicted by the genome sequence include dipeptidyl peptidases, a calpain homolog and serine-repeat antigens (SERAs). Dipeptidyl aminopeptidase 1 appears to be essential and localized to the food vacuole, suggesting a role in hemoglobin hydrolysis. Dipeptidyl aminopeptidase 3 appears to play a role in the rupture of erythrocytes by mature parasites. the P. falciparum calpain homolog gene could not be disrupted, suggesting that the protein is essential and a role in the parasite cell cycle has been suggested. Nine P. falciparum SERAs have cysteine protease motifs, but in some the active site cys is replaced by a Ser. Gene disruption studies suggested that SERA-5 and SERA-6 are essential. activation of SERA-5 by a serine protease seems to be required for merozoite egress from the erythrocyte. New drugs for malaria are greatly needed and cysteine proteases represent potential drug targets. cysteine protease inhibitors have demonstrated potent antimalarial effects and the optimization and testing of falcipain inhibitor antimalarials is underway.
129 citations
10 Jun 2011
TL;DR: The study of calpains focuses especially on recent findings about their structure–function relationships, which have been greatly aided by the development of 3D structural studies and genetic models.
Abstract: Calpain is an intracellular Ca2+-dependent cysteine protease (EC 3.4.22.17; Clan CA, family C02) discovered in 1964. It was also called CANP (Ca2+-activated neutral protease) as well as CASF, CDP, KAF, etc. until 1990. Calpains are found in almost all eukaryotes and a few bacteria, but not in archaebacteria. Calpains have a limited proteolytic activity, and function to transform or modulate their substrates' structures and activities; they are therefore called, "modulator proteases." In the human genome, 15 genes--CAPN1, CAPN2, etc.--encode a calpain-like protease domain. Their products are calpain homologs with divergent structures and various combinations of functional domains, including Ca2+-binding and microtubule-interaction domains. Genetic studies have linked calpain deficiencies to a variety of defects in many different organisms, including lethality, muscular dystrophies, gastropathy, and diabetes. This review of the study of calpains focuses especially on recent findings about their structure-function relationships. These discoveries have been greatly aided by the development of 3D structural studies and genetic models.
128 citations
TL;DR: The results show that the stringent substrate specificity of the SARS-CoV Mpro with respect to the P1 and P2 positions can be overruled by the highly electrophilic character of the aldehyde warhead, thereby constituting a deviation from the dogma that peptidic inhibitors need to correspond to the observed cleavage Specificity of the target protease.
111 citations
TL;DR: Cruzain hinders macrophage activation during the early (<60 min) stages of infection, by interruption of the NF-κB P65 mediated signaling pathway, which may lead to the spread of infection in acute Chagas' disease.
Abstract: Trypanosoma cruzi is the causative agent of Chagas' disease Novel chemotherapy with the drug K11777 targets the major cysteine protease cruzain and disrupts amastigote intracellular development Nevertheless, the biological role of the protease in infection and pathogenesis remains unclear as cruzain gene knockout failed due to genetic redundancy A role for the T cruzi cysteine protease cruzain in immune evasion was elucidated in a comparative study of parental wild type- and cruzain-deficient parasites Wild type T cruzi did not activate host macrophages during early infection (<60 min) and no increase in ∼P iκB was detected The signaling factor NF-κB P65 colocalized with cruzain on the cell surface of intracellular wild type parasites, and was proteolytically cleaved No significant IL-12 expression occurred in macrophages infected with wild type T cruzi and treated with LPS and BFA, confirming impairment of macrophage activation pathways In contrast, cruzain-deficient parasites induced macrophage activation, detectable iκB phosphorylation, and nuclear NF-κB P65 localization These parasites were unable to develop intracellularly and survive within macrophages IL 12 expression levels in macrophages infected with cruzain-deficient T cruzi were comparable to LPS activated controls Thus cruzain hinders macrophage activation during the early (<60 min) stages of infection, by interruption of the NF-κB P65 mediated signaling pathway These early events allow T cruzi survival and replication, and may lead to the spread of infection in acute Chagas' disease
96 citations
TL;DR: E64d likely reduces brain Aβ by inhibiting cathepsin B and not BACE1 β-secretase activity and that E64d therefore may have potential for treating AD patients.
Abstract: The cysteine protease cathepsin B is a potential drug target for reducing brain amyloid-β (Aβ) and improving memory in Alzheimer's disease (AD), as reduction of cathepsin B in transgenic mice expressing human wild-type amyloid-β protein precursor (AβPP) results in significantly decreased brain Aβ. Cathepsin B cleaves the wild-type β-secretase site sequence in AβPP to produce Aβ, and cathepsin B inhibitors administered to animal models expressing AβPP containing the wild-type β-secretase site sequence reduce brain Aβ in a manner consistent with β-secretase inhibition. But such inhibitors could act either by direct inhibition of cathepsin B β-secretase activity or by off-target inhibition of the other β-secretase, the aspartyl protease BACE1. To evaluate that issue, we orally administered a cysteine protease inhibitor, E64d, to normal guinea pigs or transgenic mice expressing human AβPP, both of which express the human wild-type β-secretase site sequence. In guinea pigs, oral E64d administration caused a dose-dependent reduction of up to 92% in brain, CSF, and plasma of Aβ40 and Aβ42, a reduction of up to 50% in the C-terminal β-secretase fragment (CTFβ), and a 91% reduction in brain cathepsin B activity, but increased brain BACE1 activity by 20%. In transgenic AD mice, oral E64d administration improved memory deficits and reduced brain Aβ40 and Aβ42, amyloid plaque, brain CTFβ, and brain cathepsin B activity, but increased brain BACE1 activity. We conclude that E64d likely reduces brain Aβ by inhibiting cathepsin B and not BACE1 β-secretase activity and that E64d therefore may have potential for treating AD patients.
94 citations
TL;DR: The results demonstrated that the Ec-CB might play a functional role in Singapore grouper iridovirus infection.
86 citations
TL;DR: Allostery in bacterial proteins has thus been successfully exploited in the evolutionary development of nitrosothiol-based innate immunity and may provide an avenue to new therapeutic approaches.
Abstract: The global prevalence of severe Clostridium difficile infection highlights the profound clinical significance of clostridial glucosylating toxins. Virulence is dependent on the autoactivation of a toxin cysteine protease, which is promoted by the allosteric cofactor inositol hexakisphosphate (InsP(6)). Host mechanisms that protect against such exotoxins are poorly understood. It is increasingly appreciated that the pleiotropic functions attributed to nitric oxide (NO), including host immunity, are in large part mediated by S-nitrosylation of proteins. Here we show that C. difficile toxins are S-nitrosylated by the infected host and that S-nitrosylation attenuates virulence by inhibiting toxin self-cleavage and cell entry. Notably, InsP(6)- and inositol pyrophosphate (InsP(7))-induced conformational changes in the toxin enabled host S-nitrosothiols to transnitrosylate the toxin catalytic cysteine, which forms part of a structurally conserved nitrosylation motif. Moreover, treatment with exogenous InsP(6) enhanced the therapeutic actions of oral S-nitrosothiols in mouse models of C. difficile infection. Allostery in bacterial proteins has thus been successfully exploited in the evolutionary development of nitrosothiol-based innate immunity and may provide an avenue to new therapeutic approaches.
84 citations
TL;DR: Recombinant AtMCP2d, the most abundantly expressed member of Arabidopsis type II MCPs at the transcriptional level, exhibits a strict Ca2+ dependence for its catalytic activation that is apparently mediated by intramolecular self-cleavage mechanism, and it is demonstrated that this residue is essential for AtM CP2d activation of H2O2-induced cell death in yeast.
82 citations
TL;DR: The molecular aspects of SpeB production by GAS from transcription to activation and the multiple layers of control involved are reviewed, reflecting the critical role played by this virulence factor in GAS infection.
Abstract: Streptococcal pyrogenic exotoxin B (SpeB) is a protease secreted by group A streptococci and known to degrade a wide range of host and GAS proteins in vitro. Although the role of SpeB in GAS infection is debated, recent evidence has conclusively demonstrated that SpeB is critical for the pathogenesis of severe invasive disease caused by GAS. Genetic inactivation of the speB gene results in significantly decreased virulence in a necrotizing fasciitis model of infection. Production of fully active SpeB by GAS is extremely complex. Following transcription and translation the SpeB protein is secreted as an inactive zymogen, which is autocatalytically processed through a series of intermediates to form an active protease. Each step from transcription to protease activation is tightly controlled and regulated by the bacterial cell reflecting the critical role played by this virulence factor in GAS infection. Here we review the molecular aspects of SpeB production by GAS from transcription to activation and the multiple layers of control involved.
TL;DR: Hepatitis E virus (HEV) ORF1 protein (pORF1) contains methyltransferase (MetT), papain-like cysteine protease (PCP), RNA helicase (Hel) and RNA-dependent RNA polymerase (RdRp) domains, suggesting a possible role in combating cellular antiviral pathways.
Abstract: Hepatitis E virus (HEV) ORF1 protein (pORF1) contains methyltransferase (MetT), papain-like cysteine protease (PCP), RNA helicase (Hel) and RNA-dependent RNA polymerase (RdRp) domains. ORF1 sequence analysis showed two consensus LXGG cleavage sites at 664 and 1205. LXGG sequence is recognized by viral and cellular deubiquitinating enzymes. The protein encompassing the predicted MetT-PCP domains of HEV ORF1 was tested for deubiquitinating activity using fluorogenic substrates - ubiquitin-7-amino-4-methylcoumarin (AMC), IFN-stimulated gene 15 (ISG15)-AMC, Nedd8-AMC and SUMO-AMC. MetT-PCP cleaved all four substrates but processing of ISG15-AMC was more robust. There was no processing of the Hel and RdRp domains having the conserved (1205) LXGG site by the protein. MetT-PCP carried out deISGylation of the ISG15-conjugated cellular proteins, suggesting a possible role in combating cellular antiviral pathways.
TL;DR: Results indicate that the purified protease may have potential application as a rennet substitute in the dairy industry and be classified as a member of the cysteine proteases.
TL;DR: An allosteric circuit is identified that allows bacterial virulence factors to sense and respond to the eukaryotic environment and residues within a β-hairpin region functionally couple the InsP6-binding site to the active site.
Abstract: Knowledge of the molecular mechanisms of activation of Clostridium difficile toxins will significantly enhance the ability to design specific anti-virulence therapies. Using activity-based chemical probes in combination with other techniques, this study reveals mechanistic insights into how inositol hexakisphosphate binding at the active site of the cysteine protease domain shifts the conformational equilibrium towards an active conformer.
TL;DR: It is shown that the presence of uncleaved SlpA in the cell wall of the cwp84 mutant results in aberrant retention of other cell wall proteins at the cell surface, as demonstrated by secretion of the proteins Cwp66 and Cwp2 into the growth medium.
Abstract: Clostridium difficile expresses a number of cell wall proteins, including the abundant high-molecular-weight and low-molecular-weight S-layer proteins (SLPs). These proteins are generated by posttranslational cleavage of the precursor SlpA by the cysteine protease Cwp84. We compared the phenotypes of C. difficile strains containing insertional mutations in either cwp84 or its paralog cwp13 and complemented with plasmids expressing wild-type or mutant forms of their genes. We show that the presence of uncleaved SlpA in the cell wall of the cwp84 mutant results in aberrant retention of other cell wall proteins at the cell surface, as demonstrated by secretion of the proteins Cwp66 and Cwp2 into the growth medium. These phenotypes are restored by complementation with a plasmid expressing wild-type Cwp84 enzyme but not with one encoding a Cys116Ala substitution in the active site. The cwp13 mutant cleaved the SlpA precursor normally and had a wild-type-like colony phenotype. Both Cwp84 and Cwp13 are produced as proenzymes which are processed by cleavage to produce mature enzymes. In the case of Cwp84, this cleavage does not appear to be autocatalytic, whereas in Cwp13 autocatalysis was demonstrated as a Cys109Ala mutant did not undergo processing. Cwp13 appears to have a role in processing of Cwp84 but is not essential for Cwp84 activity. Cwp13 cleaves SlpA in the HMW SLP domain, which we suggest may reflect a role in cleavage and degradation of misfolded proteins at the cell surface.
TL;DR: The present study highlights the importance of focused libraries and enrichment studies in structure-based virtual screening of a focused cysteine protease inhibitor library built with soft rather than hard electrophiles against an X-ray crystal structure of FP-2 using the Glide docking program.
Abstract: Malaria, in particular that caused by Plasmodium falciparum, is prevalent across the tropics, and its medicinal control is limited by widespread drug resistance. Cysteine proteases of P. falciparum, falcipain-2 (FP-2) and falcipain-3 (FP-3), are major hemoglobinases, validated as potential antimalarial drug targets. Structure-based virtual screening of a focused cysteine protease inhibitor library built with soft rather than hard electrophiles was performed against an X-ray crystal structure of FP-2 using the Glide docking program. An enrichment study was performed to select a suitable scoring function and to retrieve potential candidates against FP-2 from a large chemical database. Biological evaluation of 50 selected compounds identified 21 diverse nonpeptidic inhibitors of FP-2 with a hit rate of 42%. Atomic Fukui indices were used to predict the most electrophilic center and its electrophilicity in the identified hits. Comparison of predicted electrophilicity of electrophiles in identified hits with t...
TL;DR: Results show a critical role for NADPH oxidase in antimicrobial host defense against A. fumigatus and B. cepacia, whereas the proteases evaluated were dispensable.
Abstract: NADPH oxidase is a crucial enzyme in mediating antimicrobial host defense and in regulating inflammation. Patients with chronic granulomatous disease, an inherited disorder of NADPH oxidase in which phagocytes are defective in generation of reactive oxidant intermediates (ROIs), suffer from life-threatening bacterial and fungal infections. The mechanisms by which NADPH oxidase mediate host defense are unclear. In addition to ROI generation, neutrophil NADPH oxidase activation is linked to the release of sequestered proteases that are posited to be critical effectors of host defense. To definitively determine the contribution of NADPH oxidase versus neutrophil serine proteases, we evaluated susceptibility to fungal and bacterial infection in mice with engineered disruptions of these pathways. NADPH oxidase-deficient mice (p47(phox-/-)) were highly susceptible to pulmonary infection with Aspergillus fumigatus. In contrast, double knockout neutrophil elastase (NE)(-/-)×cathepsin G (CG)(-/-) mice and lysosomal cysteine protease cathepsin C/dipeptidyl peptidase I (DPPI)-deficient mice that are defective in neutrophil serine protease activation demonstrated no impairment in antifungal host defense. In separate studies of systemic Burkholderia cepacia infection, uniform fatality occurred in p47(phox-/-) mice, whereas NE(-/-)×CG(-/-) mice cleared infection. Together, these results show a critical role for NADPH oxidase in antimicrobial host defense against A. fumigatus and B. cepacia, whereas the proteases we evaluated were dispensable. Our results indicate that NADPH oxidase dependent pathways separate from neutrophil serine protease activation are required for host defense against specific pathogens.
TL;DR: The X-ray structure of the Southampton norovirus 3C protease (SV3CP) bound to an active site-directed peptide inhibitor (MAPI) which has been refined at 1.7 Å resolution provides important new information for the development of antiviral prophylactics.
Abstract: Noroviruses are the major cause of human epidemic nonbacterial gastroenteritis. Viral replication requires a 3C cysteine protease that cleaves a 200 kDa viral polyprotein into its constituent functional proteins. Here we describe the X-ray structure of the Southampton norovirus 3C protease (SV3CP) bound to an active site-directed peptide inhibitor (MAPI) which has been refined at 1.7 A resolution. The inhibitor, acetyl-Glu-Phe-Gln-Leu-Gln-X, which is based on the most rapidly cleaved recognition sequence in the 200 kDa polyprotein substrate, reacts covalently through its propenyl ethyl ester group (X) with the active site nucleophile, Cys 139. The structure permits, for the first time, the identification of substrate recognition and binding groups in a noroviral 3C protease and thus provides important new information for the development of antiviral prophylactics.
TL;DR: It is shown that USP2a mediates mitotic progression by regulating the stability of Aurora-A, a member of a subfamily of deubiquitinases, called ubiquitin-specific cysteine proteases (USPs) and which has been reported to be a bona fide oncogene that regulates the Stability of MDM2, MDMX, and FAS.
TL;DR: The prominent serine protease activity of A. fumigatus, which caused the overproduction of mucus by the bronchial epithelium via the activation of the TACE/TGF-α/epidermal growth factor receptor pathway, may be a pathogenetic mechanism of allergic bronchopulmonary mycosis.
Abstract: Allergic bronchopulmonary mycosis, characterized by excessive mucus secretion, airflow limitation, bronchiectasis, and peripheral blood eosinophilia, is predominantly caused by a fungal pathogen, Aspergillus fumigatus. Using DNA microarray analysis of NCI-H292 cells, a human bronchial epithelial cell line, stimulated with fungal extracts from A. fumigatus, Alternaria alternata, or Penicillium notatum, we identified a mucin-related MUC5AC as one of the genes, the expression of which was selectively induced by A. fumigatus. Quantitative RT-PCR, ELISA, and histochemical analyses confirmed an induction of mucin and MUC5AC expression by A. fumigatus extracts or the culture supernatant of live microorganisms in NCI-H292 cells and primary cultures of airway epithelial cells. The expression of MUC5AC induced by A. fumigatus extracts diminished in the presence of neutralizing Abs or of inhibitors of the epidermal growth factor receptor or its ligand, TGF-α. We also found that A. fumigatus extracts activated the TNF-α-converting enzyme (TACE), critical for the cleavage of membrane-bound pro-TGF-α, and its inhibition with low-molecular weight inhibitors or small interfering RNA suppressed the expression of MUC5AC. The protease activity of A. fumigatus extracts was greater than that of other fungal extracts, and treatment with a serine protease inhibitor, but not with a cysteine protease inhibitor, eliminated its ability to activate TACE or induce the expression of MUC5AC mRNA in NCI-H292. In conclusion, the prominent serine protease activity of A. fumigatus, which caused the overproduction of mucus by the bronchial epithelium via the activation of the TACE/TGF-α/epidermal growth factor receptor pathway, may be a pathogenetic mechanism of allergic bronchopulmonary mycosis.
TL;DR: The results show that UPI is a dual-specificity PI that functions in plant growth and defense, probably through the regulation of endogenous proteases and/or those of biotic invaders.
Abstract: Summary
Protease inhibitors (PIs) function in the precise regulation of proteases, and are thus involved in diverse biological processes in many organisms. Here, we studied the functions of the Arabidopsis UNUSUAL SERINE PROTEASE INHIBITOR (UPI) gene, which encodes an 8.8 kDa protein of atypical sequence relative to other PIs. Plants harboring a loss-of-function UPI allele displayed enhanced susceptibility to the necrotrophic fungi Botrytis cinerea and Alternaria brassicicola as well as the generalist herbivore Trichoplusia ni. Further, ectopic expression conferred increased resistance to B. cinerea and T. ni. In contrast, the mutant has wild-type responses to virulent, avirulent and non-pathogenic strains of Pseudomonas syringae, thus limiting the defense function of UPI to necrotrophic fungal infection and insect herbivory. Expression of UPI is significantly induced by jasmonate, salicylic acid and abscisic acid, but is repressed by ethylene, indicating complex phytohormone regulation of UPI expression. The upi mutant also shows significantly delayed flowering, associated with decreased SOC1 expression and elevated levels of MAF1, two regulators of floral transition. Recombinant UPI strongly inhibits the serine protease chymotrypsin but also weakly blocks the cysteine protease papain. Interestingly, jasmonate induces intra- and extracellular UPI accumulation, suggesting a possible role in intercellular or extracellular functions. Overall, our results show that UPI is a dual-specificity PI that functions in plant growth and defense, probably through the regulation of endogenous proteases and/or those of biotic invaders.
TL;DR: The key features and roles of T. gondii cathepsins are reviewed, the therapeutic potential for specific inhibitor development is discussed and the scientific rationale behind the C1 family of cysteine proteases is explained.
Abstract: Cysteine proteases are important for the growth and survival of apicomplexan parasites that infect humans. The apicomplexan Toxoplasma gondii expresses five members of the C1 family of cysteine proteases, including one cathepsin L-like (TgCPL), one cathepsin B-like (TgCPB) and three cathepsin C-like (TgCPC1, 2 and 3) proteases. Recent genetic, biochemical and structural studies reveal that cathepsins function in microneme and rhoptry protein maturation, host cell invasion, replication and nutrient acquisition. here, we review the key features and roles of T. gondii cathepsins and discuss the therapeutic potential for specific inhibitor development.
TL;DR: It is proposed that the molecular targets of these compounds are thiol-containing biological molecules such as the cathepsin cysteine proteases, implicated in many diseases including cancer, which are accessible to the interaction of thiophilic metals such as gold.
TL;DR: Mutagenesis studies were carried out to provide the structural basis for understanding the loss of catalytic activity observed in a recently identified UfSP2 mutation that is associated with an autosomal dominant form of hip dysplasia.
TL;DR: The crystal structure of the cysteine protease domain of HC-Pro from turnip mosaic virus is determined at 2.0 Å resolution and provides insight into the catalysis mechanism, cis-acting mode, cleavage site specificity, and other functions of the HC- pro proteasedomain.
TL;DR: In studies showed that individual inhibitors of cysteine proteases provided significant neuroprotection in animal models of SCI, physiological hormones, such as estrogen and melatonin, can be successfully used for prevention of neurodegeneration and preservation of motor function in acute SCI as well as in chronic SCI in rats.
TL;DR: A soluble form of TLR9 (sTLR9) was generated by a novel proteolytic event that cleaved TLR 9 between amino acids 724–735 and this data support a model where an intrinsic proteolytically processing mechanism negatively regulates TLR7‐dependent signaling.
Abstract: Nucleic acids structures are highly conserved through evolution and when self nucleic acids are aberrantly detected by Toll-Like Receptors (TLRs) they contribute to autoimmune disease. For this reason, multiple regulatory mechanisms exist to prevent response to self nucleic acids. TLR9 is a nucleic acid sensing TLR that is regulated at multiple levels including association with accessory proteins, intracellular localization and proteolytic processing. In the endolysosomal compartment TLR9 is proteolytically processed to an 80 kilodalton form (p80) and this processing is a prerequisite for activation. Here we identified a soluble form of TLR9 generated by a novel proteolytic event that cleaved TLR9 between amino acids 724–735. Similar to p80, sTLR9 was generated in endosomes. However, generation of sTLR9 was independent of the cysteine protease cathepsin B active at acidic pH, but partially dependent on cathepsin S, a protease active at neutral pH. Most importantly, sTLR9 inhibited TLR9-dependent signaling. Together, these data support a model where an intrinsic proteolytic processing mechanism negatively regulates TLR9 signaling. Proper balance between the independent proteolytic events likely contributes to regulation of TLR9 mediated innate immunity and prevention of autoimmune disease.
TL;DR: Staphylococcus aureus remains one of the major humanpathogens, causing a number of diverse infections, and in vitro experiments have demonstrated a very broad activity of these enzymes, including destruction of connective tissue, disturbance of clotting and kinin systems and direct interaction with host immune cells.
Abstract: Staphylococcus aureus remains one of the major humanpathogens, causing a number of diverse infections. the growing antibiotic resistance, including vancomycin and methicilin-resistant strains raises the special interest in virulence mechanism of this pathogen. among a number of extracellular virulence factors, S. aureus secretes several proteases of three catalytic classes—metallo, serine and papain-like cysteine proteases. the expression of proteolytic enzymes is strictly controlled by global regulators of virulence factors expression agr and sar and proteases take a role in a phenotype change in postlogarithmic phase of growth. the staphylococcal proteases are secreted as proenzymes and undergo activation in a cascade manner.
TL;DR: High-throughput proteomics was used to identify secretome, the global pattern of secreted proteins, in human primary macrophages that had been activated through the cytoplasmic dsRNA-recognition pathway, and emphasized the importance of cathepsins in the innate immune response to virus infection.
Abstract: dsRNA is an important pathogen-associated molecular pattern that is primarily recognized by cytosolic pattern-recognition receptors of the innate-immune system during virus infection. This recognition results in the activation of inflammasome-associated caspase-1 and apoptosis of infected cells. In this study, we used high-throughput proteomics to identify secretome, the global pattern of secreted proteins, in human primary macrophages that had been activated through the cytoplasmic dsRNA-recognition pathway. The secretome analysis revealed cytoplasmic dsRNA-recognition pathway-induced secretion of several exosome-associated proteins, as well as basal and dsRNA-activated secretion of lysosomal protease cathepsins and cysteine protease inhibitors (cystatins). Inflammasome activation was almost completely abolished by cathepsin inhibitors in response to dsRNA stimulation, as well as encephalomyocarditis virus and vesicular stomatitis virus infections. Interestingly, Western blot analysis showed that the mature form of cathepsin D, but not cathepsin B, was secreted simultaneously with IL-18 and inflammasome components ASC and caspase-1 in cytoplasmic dsRNA-stimulated cells. Furthermore, small interfering RNA-mediated silencing experiments confirmed that cathepsin D has a role in inflammasome activation. Caspase-1 activation was followed by proteolytic processing of caspase-3, indicating that inflammasome activation precedes apoptosis in macrophages that had recognized cytoplasmic RNA. Like inflammasome activation, apoptosis triggered by dsRNA stimulation and virus infection was effectively blocked by cathepsin inhibition. In conclusion, our results emphasize the importance of cathepsins in the innate immune response to virus infection.
TL;DR: The latex of Ficus carica constitutes an important source of many proteolytic components known under the general term of ficin, which belongs to the cysteine proteases of the papain family, and data on the purification and characterization of individual forms of these proteases reinforce the view that they belong to the family of papain-like proteases.