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Frontiers in Immunology 2022Melanization is an integral part of the insect defense system and is often induced by pathogen invasion. Phenoloxidases (POs) are critical enzymes that catalyze melanin...
Melanization is an integral part of the insect defense system and is often induced by pathogen invasion. Phenoloxidases (POs) are critical enzymes that catalyze melanin formation. PO3 is associated with the antifungal response of the mosquito, , but the molecular mechanism of the prophenoloxidase-3 (PPO3) activation is unclear. Here we report that PPO3 cleavage activation is mediated by a clip-domain serine protease, CLIPB9. We purified recombinant CLIPB9 and found that it cleaved PPO3 and increased PO activity in the hemolymph. We then identified CLIPA14 (a serine protease homolog) by co-immunoprecipitation using anti-CLIPB9 antibody. After being cleaved by CLIPB9, CLIPA14 acted as a cofactor for PPO3 activation. In addition, dsRNA co-silencing of and genes reduced melanization after infection with the entomopathogen, , making the adult mosquitoes more sensitive to fungal infection. These results illustrate the roles of CLIPB9 and CLIPA14 in the PPO activation pathway and revealed the complexity of the upstream serine protease network controlling melanization.
Topics: Aedes; Animals; Catechol Oxidase; Enzyme Precursors; Melanins; Monophenol Monooxygenase; Mycoses; Serine Endopeptidases; Serine Proteases
PubMed: 35967454
DOI: 10.3389/fimmu.2022.927322 -
Molecular Microbiology Oct 1997HtrA, also known as DegP and probably identical to the Do protease, is a heat shock-induced serine protease that is active in the periplasm of Escherichia coli.... (Review)
Review
HtrA, also known as DegP and probably identical to the Do protease, is a heat shock-induced serine protease that is active in the periplasm of Escherichia coli. Homologues of HtrA have been described in a wide range of bacteria and in eukaryotes. Its chief role is to degrade misfolded proteins in the periplasm. Substrate recognition probably involves the recently described PDZ domains in the C-terminal half of HtrA and, we suspect, has much in common with the substrate recognition system of the tail-specific protease, Prc (which also possesses a PDZ domain). The expression of htrA is regulated by a complex set of signal transduction pathways, which includes an alternative sigma factor, RpoE, an anti-sigma factor, RseA, a two-component regulatory system, CpxRA, and two phosphoprotein phosphatases, PrpA and PrpB. Mutations in the htrA genes of Salmonella, Brucella and Yersinia cause decreased survival in mice and/or macrophages, and htrA mutants can act as vaccines, as cloning hosts and as carriers of heterologous antigens.
Topics: Amino Acid Sequence; Animals; Bacteria; Bacterial Proteins; Heat-Shock Proteins; Humans; Mice; Molecular Sequence Data; Periplasmic Proteins; Sequence Alignment; Serine Endopeptidases
PubMed: 9383148
DOI: 10.1046/j.1365-2958.1997.5601928.x -
Frontiers in Bioscience (Landmark... Jan 2011The Type II transmembrane serine proteases (TTSP) are a relatively newly identified family of proteolytic enzymes that have become the subject of intense scrutiny in the... (Review)
Review
The Type II transmembrane serine proteases (TTSP) are a relatively newly identified family of proteolytic enzymes that have become the subject of intense scrutiny in the field of cancer research. Advances in genome screening technology have enabled the identification of putative members and the further characterization of existing members. The TTSPs are involved in a diverse range of physiological functions and new roles continue to be discovered. A large majority of these proteases appear to play crucial roles in the development of disease, especially cancer development and progression. This review presents the current knowledge of the biological role of those TTSPs that have been identified in the development and progression of human cancers.
Topics: Animals; Humans; Male; Membrane Proteins; Mice; Neoplasm Proteins; Neoplasms; Prostatic Neoplasms; Serine Endopeptidases
PubMed: 21196187
DOI: 10.2741/3704 -
Virulence Dec 2021(meningococcus) is a common bacterial colonizer of the human nasopharynx but can occasionally cause very severe systemic infections with rapid onset. Meningococci are...
(meningococcus) is a common bacterial colonizer of the human nasopharynx but can occasionally cause very severe systemic infections with rapid onset. Meningococci are able to degrade IgA encountered during colonization of mucosal membranes using their IgA1-specific serine protease. During systemic infection, specific IgG can induce complement-mediated lysis of the bacterium. However, meningococcal immune evasion mechanisms in thwarting IgG remain undescribed. In this study, we report for the first time that the meningococcal IgA1-specific serine protease is able to degrade IgG3 in addition to IgA. The IgG3 heavy chain is specifically cleaved in the lower hinge region thereby separating the antigen binding part from its effector binding part. Through molecular characterization, we demonstrate that meningococcal IgA1-specific serine protease of cleavage type 1 degrades both IgG3 and IgA, whereas cleavage type 2 only degrades IgA. Epidemiological analysis of 7581 clinical meningococcal isolates shows a significant higher proportion of cleavage type 1 among isolates from invasive cases compared to carrier cases, regardless of serogroup. Notably, serogroup W cc11 which is an increasing cause of invasive meningococcal disease globally harbors almost exclusively cleavage type 1 protease. Our study also shows an increasing prevalence of meningococcal isolates encoding IgA1P cleavage type 1 compared to cleavage type 2 during the observed decade (2010-2019). Altogether, our work describes a novel mechanism of IgG3 degradation by meningococci and its association to invasive meningococcal disease.
Topics: Humans; Immunoglobulin G; Meningococcal Infections; Neisseria meningitidis; Serine; Serine Endopeptidases; Serine Proteases
PubMed: 33459578
DOI: 10.1080/21505594.2021.1871822 -
PLoS Genetics Jun 2023The mechanisms by which the innate immune system senses damage have been extensively explored in multicellular organisms. In Drosophila, various types of tissue damage,...
The mechanisms by which the innate immune system senses damage have been extensively explored in multicellular organisms. In Drosophila, various types of tissue damage, including epidermal injury, tumor formation, cell competition, and apoptosis deficiency, induce sterile activation of the Toll pathway, a process that requires the use of extracellular serine protease (SP) cascades. Upon infection, the SP Spätzle (Spz)-processing enzyme (SPE) cleaves and activates the Toll ligand Spz downstream of two paralogous SPs, Hayan and Persephone (Psh). However, upon tissue damage, it is not fully understood which SPs establish Spz activation cascades nor what damage-associated molecules can activate SPs. In this study, using newly generated uncleavable spz mutant flies, we revealed that Spz cleavage is required for the sterile activation of the Toll pathway, which is induced by apoptosis-deficient damage of wing epidermal cells in adult Drosophila. Proteomic analysis of hemolymph, followed by experiments with Drosophila Schneider 2 (S2) cells, revealed that among hemolymph SPs, both SPE and Melanization Protease 1 (MP1) have high capacities to cleave Spz. Additionally, in S2 cells, MP1 acts downstream of Hayan and Psh in a similar manner to SPE. Using genetic analysis, we found that the upstream SPs Hayan and Psh contributes to the sterile activation of the Toll pathway. While SPE/MP1 double mutants show more impairment of Toll activation upon infection than SPE single mutants, Toll activation is not eliminated in these apoptosis-deficient flies. This suggests that Hayan and Psh sense necrotic damage, inducing Spz cleavage by SPs other than SPE and MP1. Furthermore, hydrogen peroxide, a representative damage-associated molecule, activates the Psh-Spz cascade in S2 cells overexpressing Psh. Considering that reactive oxygen species (ROS) were detected in apoptosis-deficient wings, our findings highlight the importance of ROS as signaling molecules that induce the activation of SPs such as Psh in response to damage.
Topics: Animals; Serine Proteases; Drosophila Proteins; Toll-Like Receptors; Proteomics; Reactive Oxygen Species; Serine Endopeptidases; Drosophila; Apoptosis
PubMed: 37319131
DOI: 10.1371/journal.pgen.1010761 -
The International Journal of... 2008Neutrophil serine proteases are granule-associated enzymes known mainly for their function in the intracellular killing of pathogens. Their extracellular release upon... (Review)
Review
Neutrophil serine proteases are granule-associated enzymes known mainly for their function in the intracellular killing of pathogens. Their extracellular release upon neutrophil activation is traditionally regarded as the primary reason for tissue damage at the sites of inflammation. However, studies over the past several years indicate that neutrophil serine proteases may also be key regulators of the inflammatory response. Neutrophil serine proteases specifically process and release chemokines, cytokines, and growth factors, thus modulating their biological activity. In addition, neutrophil serine proteases activate and shed specific cell surface receptors, which can ultimately prolong or terminate cytokine-induced responses. Moreover, it has been proposed that these proteases can impact cell viability through their caspase-like activity and initiate the adaptive immune response by directly activating lymphocytes. In summary, these studies point to neutrophil serine proteases as versatile mediators that fine-tune the local immune response and identify them as potential targets for therapeutic interventions.
Topics: Animals; Humans; Inflammation; Models, Biological; Neutrophil Activation; Neutrophils; Serine Endopeptidases
PubMed: 18180196
DOI: 10.1016/j.biocel.2007.11.008 -
The Journal of Clinical Investigation Mar 1990Two 29-kD polypeptides, azurocidin and p29b, were purified to homogeneity from human neutrophils by acid extraction of azurophil granule membrane-associated material...
Two 29-kD polypeptides, azurocidin and p29b, were purified to homogeneity from human neutrophils by acid extraction of azurophil granule membrane-associated material followed by gel filtration and reverse-phase chromatography. Azurocidin and p29b share NH2-terminal sequence homology with each other as well as with elastase, cathepsin G, and other serine proteases. p29b bound [3H]diisopropyl fluorophosphate and hydrolyzed elastin, casein, and hemoglobin. A peptide substrate for p29b could not be identified. Azurocidin neither bound [3H]diisopropyl fluorophosphate nor hydrolyzed any of the proteins, peptides, or esters tested. In microbicidal assays, purified azurocidin was comparable to p29b in activity against Escherichia coli, Streptococcus faecalis, and Candida albicans. The antimicrobial activity of azurocidin was enhanced under mildly acidic conditions, but was inhibited in a dose-dependent manner by NaCl, CaCl2, or serum. Immunoblot analysis with monospecific antibodies localized greater than 90% of the azurocidin and greater than 75% of the p29b to azurophil granule-rich fractions of PMN lysates. Immunoelectron microscopy confirmed the localization of azurocidin to the azurophil granules. Azurocidin associated with the azurophil granule membrane, but did not appear to be an integral membrane protein. Thus, azurocidin and p29b are members of a family of serine protease homologs stored in azurophil granules and may play a role in inflammatory and antimicrobial processes involving PMN.
Topics: Anti-Infective Agents; Antimicrobial Cationic Peptides; Blood Bactericidal Activity; Blood Proteins; Carrier Proteins; Cathepsin G; Cathepsins; Cytoplasmic Granules; Humans; Hydrogen-Ion Concentration; Neutrophils; Osmolar Concentration; Pancreatic Elastase; Serine Endopeptidases
PubMed: 2312733
DOI: 10.1172/JCI114518 -
Biomolecules Jun 2022A conserved, 26-residue sequence [AA(X)[A/G][G/L](X)GDV[I/L](X)[V/L]NGE(X)V(X)] and corresponding structure repeating module were identified within the HtrA protease...
A conserved, 26-residue sequence [AA(X)[A/G][G/L](X)GDV[I/L](X)[V/L]NGE(X)V(X)] and corresponding structure repeating module were identified within the HtrA protease family using a non-redundant set (N = 20) of publicly available structures. While the repeats themselves were far from sequence perfect, they had notable conservation to a statistically significant level. Three or more repetitions were identified within each protein despite being statistically expected to randomly occur only once per 1031 residues. This sequence repeat was associated with a six stranded antiparallel β-barrel module, two of which are present in the core of the structures of the PA clan of serine proteases, while a modified version of this module could be identified in the PDZ-like domains. Automated structural alignment methods had difficulties in superimposing these β-barrels, but the use of a target human HtrA2 structure showed that these modules had an average RMSD across the set of structures of less than 2 Å (mean and median). Our findings support Dayhoff's hypothesis that complex proteins arose through duplication of simpler peptide motifs and domains.
Topics: Humans; Peptides; Serine Endopeptidases; Serine Proteases
PubMed: 35740918
DOI: 10.3390/biom12060793 -
American Journal of Physiology.... Sep 2016Barrier dysfunction is a characteristic of the inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Understanding how the tight junction is...
Barrier dysfunction is a characteristic of the inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Understanding how the tight junction is modified to maintain barrier function may provide avenues for treatment of IBD. We have previously shown that the apical addition of serine proteases to intestinal epithelial cell lines causes a rapid and sustained increase in transepithelial electrical resistance (TER), but the mechanisms are unknown. We hypothesized that serine proteases increase barrier function through trafficking and insertion of tight junction proteins into the membrane, and this could enhance recovery of a disrupted monolayer after calcium switch or cytokine treatment. In the canine epithelial cell line, SCBN, we showed that matriptase, an endogenous serine protease, could potently increase TER. Using detergent solubility-based cell fractionation, we found that neither trypsin nor matriptase treatment changed levels of tight junction proteins at the membrane. In a fast calcium switch assay, serine proteases did not enhance the rate of recovery of the junction. In addition, serine proteases could not reverse barrier disruption induced by IFNγ and TNFα. We knocked down occludin in our cells using siRNA and found this prevented the serine protease-induced increase in TER. Using fluorescence recovery after photobleaching (FRAP), we found serine proteases induce a greater mobile fraction of occludin in the membrane. These data suggest that a functional tight junction is needed for serine proteases to have an effect on TER, and that occludin is a crucial tight junction protein in this mechanism.
Topics: Animals; Cell Line; Dogs; Electric Impedance; Electrophysiological Phenomena; Epithelial Cells; Intestinal Mucosa; Occludin; Protein Transport; Serine Endopeptidases; Serine Proteases; Tight Junction Proteins; Tight Junctions; Trypsin
PubMed: 27492333
DOI: 10.1152/ajpgi.00441.2015 -
Proceedings of the National Academy of... Feb 2022Magnetosomes are lipid-bound organelles that direct the biomineralization of magnetic nanoparticles in magnetotactic bacteria. Magnetosome membranes are not uniform in...
Magnetosomes are lipid-bound organelles that direct the biomineralization of magnetic nanoparticles in magnetotactic bacteria. Magnetosome membranes are not uniform in size and can grow in a biomineralization-dependent manner. However, the underlying mechanisms of magnetosome membrane growth regulation remain unclear. Using cryoelectron tomography, we systematically examined mutants with defects at various stages of magnetosome formation to identify factors involved in controlling membrane growth. We found that a conserved serine protease, MamE, plays a key role in magnetosome membrane growth regulation. When the protease activity of MamE is disrupted, magnetosome membrane growth is restricted, which, in turn, limits the size of the magnetite particles. Consistent with this finding, the upstream regulators of MamE protease activity, MamO and MamM, are also required for magnetosome membrane growth. We then used a combination of candidate and comparative proteomics approaches to identify Mms6 and MamD as two MamE substrates. Mms6 does not appear to participate in magnetosome membrane growth. However, in the absence of MamD, magnetosome membranes grow to a larger size than the wild type. Furthermore, when the cleavage of MamD by MamE protease is blocked, magnetosome membrane growth and biomineralization are severely inhibited, phenocopying the MamE protease-inactive mutant. We therefore propose that the growth of magnetosome membranes is controlled by a protease-mediated switch through processing of MamD. Overall, our work shows that, like many eukaryotic systems, bacteria control the growth and size of biominerals by manipulating the physical properties of intracellular organelles.
Topics: Bacterial Proteins; Ferrosoferric Oxide; Magnetosomes; Magnetospirillum; Organelles; Proteolysis; Proteomics; Serine Endopeptidases; Serine Proteases
PubMed: 35110403
DOI: 10.1073/pnas.2111745119