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Protease Complex (protease + complex)
Selected AbstractsThe antibiotic ADEP reprogrammes ClpP, switching it from a regulated to an uncontrolled proteaseEMBO MOLECULAR MEDICINE, Issue 1 2009Janine Kirstein Abstract A novel class of antibiotic acyldepsipeptides (designated ADEPs) exerts its unique antibacterial activity by targeting the peptidase caseinolytic protease P (ClpP). ClpP forms proteolytic complexes with heat shock proteins (Hsp100) that select and process substrate proteins for ClpP-mediated degradation. Here, we analyse the molecular mechanism of ADEP action and demonstrate that ADEPs abrogate ClpP interaction with cooperating Hsp100 adenosine triphosphatases (ATPases). Consequently, ADEP treated bacteria are affected in ClpP-dependent general and regulatory proteolysis. At the same time, ADEPs also activate ClpP by converting it from a tightly regulated peptidase, which can only degrade short peptides, into a proteolytic machinery that recognizes and degrades unfolded polypeptides. In vivo nascent polypeptide chains represent the putative primary target of ADEP-activated ClpP, providing a rationale for the antibacterial activity of the ADEPs. Thus, ADEPs cause a complete functional reprogramming of the Clp,protease complex. [source] The lectin-complement pathway , its role in innate immunity and evolutionIMMUNOLOGICAL REVIEWS, Issue 1 2004Teizo Fujita Summary:, Innate immunity was formerly thought to be a non-specific immune response characterized by phagocytosis. However, innate immunity has considerable specificity and is capable of discriminating between pathogens and self. Recognition of pathogens is mediated by a set of pattern recognition receptors, which recognize conserved pathogen-associated molecular patterns (PAMPs) shared by broad classes of microorganisms, thereby successfully defending invertebrates and vertebrates against infection. Lectins, carbohydrate-binding proteins, play an important role in innate immunity by recognizing a wide range of pathogens. Mannose-binding lectin (MBL) and ficolin are lectins composed of a lectin domain attached to collagenous region. However, they use a different lectin domain: a carbohydrate recognition domain (CRD) is responsible for MBL and a fibrinogen-like domain for ficolin. These two collagenous lectins are pattern recognition receptors, and upon recognition of the infectious agent, they trigger the activation of the lectin-complement pathway through attached serine proteases, MBL-associated serine proteases (MASPs). A similar lectin-based complement system, consisting of the lectin,protease complex and C3, is present in ascidians, our closest invertebrate relatives, and functions in an opsonic manner. We isolated several lectins homologous to MBLs and ficolins and several MASPs in invertebrates and lower vertebrates, and herein we discuss the molecular evolution of these molecules. Based on these findings, it seems likely that the complement system played a pivotal role in innate immunity before the evolution of an acquired immune system in jawed vertebrates. [source] Purification and characterization of a 630 kDa bacterial killing metalloprotease (KilC) isolated from plaice Pleuronectes platessa (L.), epidermal mucusJOURNAL OF FISH DISEASES, Issue 5 2008T Tvete Abstract Antibacterial chemicals in the mucus of fish such as lysozyme, lectins, peptides and proteases provide an efficient first line of defence against pathogens. This study shows that there are at least three antibacterial proteins in plaice skin mucus in addition to lysozyme. One of these proteins is responsible for approximately 74% of the antibacterial activity and is a 630 kDa protease complex designated KilC (bacterial killing metalloprotease C). Purified KilC kills the bacteria Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa efficiently. The protease activity of KilC is dependent upon the divalent cation Mg2+ and shows pH dual optima of 5.0 and 8.0. The enzyme has a temperature optimum of 25 °C and is made up of at least five different sized peptides. Studies with protease inhibitors show that the catalytic site of KilC may be cysteine- or serine protease-like. KilC may kill bacterial cells by acting directly upon the bacteria or by producing low molecular weight bioactive compounds such as peptides. [source] Identity and function of ,-secretaseJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2003W. Taylor Kimberly Abstract ,-Secretase catalyzes intramembrane proteolysis of various type I membrane proteins, including the amyloid-, precursor protein and the Notch receptor. Despite its importance in the pathogenesis of Alzheimer's disease and to normal development, this protease has eluded identification until only very recently. Four membrane proteins are now known to be members of the protease complex: presenilin, nicastrin, aph-1, and pen-2. Recent findings suggest that these four proteins are sufficient to reconstitute the active ,-secretase complex and that together they mediate the cell surface signaling of a variety of receptors via intramembrane proteolysis. © 2003 Wiley-Liss, Inc. [source] Relative protective properties of three membrane glycoprotein fractions from Haemonchus contortusPARASITE IMMUNOLOGY, Issue 2 2000Smith Jacalin lectin was used as a ligand to isolate a fraction containing two distinct protective antigens from detergent extracts of membranes from Haemonchus contortus. The first antigen was identified as a complex which appeared very similar to Haemonchus galactose-containing glycoprotein (H-gal-GP), which is a previously described protective protease complex, except that it was substantially depleted of one of the main H-gal-GP components, a 230 kDa metallopeptidase-containing band. The new complex was termed Haemonchus sialylated galactose-containing glycoprotein (H-sialgal-GP), because it bound to jacalin but not to peanut lectin and only jacalin will bind the sialylated form of galactosyl (,-1,3) N -acetylgalactosamine. Two protection trials with sheep showed that H-sialgal-GP and H-gal-GP were equally efficacious, reducing numbers of Haemonchus eggs by between 86% and 93% and worms by between 52% and 75%, respectively. The second jacalin-binding protective antigen fraction was separated from H-sialgal-GP by ion exchange and gel filtration chromatography. It was greatly enriched for two proteins termed p46 and p52 according to their apparent molecular weights. Immunization of sheep with these proteins gave protection values of 78% for eggs and 33% for worms, which are significantly lower than those obtained with either H-gal-GP or H-sialgal-GP. N -terminal amino acid sequence data from p46 and p52 showed that both proteins were closely related to a previously described 45 kDa Haemonchus membrane protein, which had conferred protection against Haemonchus in guinea-pigs. [source] A distinct binding mode of a hydroxyethylamine isostere inhibitor of HIV-1 proteaseACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2001Jan Dohnálek Crystallization conditions for an HIV-1 protease,inhibitor complex were optimized to produce crystals suitable for X-ray diffraction experiments. The X-ray structure of the HIV-1 protease complex was solved and refined at 3.1,Ĺ resolution. In contrast to Saquinavir, the mimetic hydroxy group of the inhibitor Boc-Phe-,[(S)-CH(OH)CH2NH]-Phe-Glu-Phe-NH2 is placed asymmetrically with respect to the non-crystallographic twofold axis of the protease dimer so that hydrogen bonds between the amino group of the inhibitor and the catalytic aspartates can be formed. The inhibitor binds in the centre of the active site by a compact network of hydrogen bonds to Gly27, Gly127, Asp25, Asp125 and via the buried water molecule W301 to Ile50 and Ile150. [source] Activation of ERK signaling upon alternative protease nexin-1 internalization mediated by syndecan-1JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2006Xiaobiao Li Abstract Protease nexin-1 (PN-1), an inhibitor of serine proteases, contributes to tissue homeostasis and influences the behavior of some tumor cells. The internalization of PN-1 protease complexes is considered to be mediated by the low-density lipoprotein receptor related protein 1 (LRP1). In this study, both wild-type and LRP1,/, mouse embryonic fibroblasts (MEF) were shown to internalize PN-1. Receptor associated protein (RAP) interfered with PN-1 uptake only in wild-type MEF cells, indicating that another receptor mediates PN-1 uptake in the absence of LRP1. In LRP1,/, MEF cells, inhibitor sensitivity and kinetic values (t1/2 at 45 min) of PN-1 uptake showed a similarity to syndecan-1-mediated endocytosis. In these cells, PN-1 uptake was increased by overexpression of full-length syndecan-1 and decreased by RNA interference targeting this proteoglycan. Most important, in contrast to PKA activation known to be triggered by LRP1-mediated internalization, our study shows that syndecan-1-mediated internalization of PN-1 stimulated the Ras-ERK signaling pathway. J. Cell. Biochem. 99: 936,951, 2006. © 2006 Wiley-Liss, Inc. [source] AutoDock4 and AutoDockTools4: Automated docking with selective receptor flexibilityJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 16 2009Garrett M. Morris Abstract We describe the testing and release of AutoDock4 and the accompanying graphical user interface AutoDockTools. AutoDock4 incorporates limited flexibility in the receptor. Several tests are reported here, including a redocking experiment with 188 diverse ligand-protein complexes and a cross-docking experiment using flexible sidechains in 87 HIV protease complexes. We also report its utility in analysis of covalently bound ligands, using both a grid-based docking method and a modification of the flexible sidechain technique. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 [source] | ||||||||||||||||