Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The MtrAB two-component signal transduction system is highly conserved in sequence and genomic organization in Mycobacterium and Corynebacterium species, but its function is completely unknown. Here, the role of MtrAB was studied with C. glutamicum as model organism. In contrast to M. tuberculosis, it was possible to delete the mtrAB genes in C. glutamicum. The mutant cells showed a radically different cell morphology and were more sensitive to penicillin, vancomycin and lysozyme but more resistant to ethambutol. In order to identify the molecular basis for this pleiotropic phenotype, the mRNA profiles of mutant and wild type were compared with DNA microarrays. Three genes showed a more than threefold increased RNA level in the mutant, i.e. mepA (NCgl2411) encoding a putative secreted metalloprotease, ppmA (NCgl2737 ) encoding a putative membrane-bound protease modulator, and lpqB encoding a putative lipoprotein of unknown function. Expression of plasmid-encoded mepA in Escherichia coli led to elongated cells that were hypersensitive to an osmotic downshift, supporting the idea that peptidoglycan is the target of MepA. The mRNA level of two genes was more than fivefold decreased in the mutant, i.e. betP and proP which encode transporters for the uptake of betaine and proline respectively. The microarray results were confirmed by primer extension and RNA dot blot experiments. In the latter, the transcript level of genes involved in osmoprotection was tested before and after an osmotic upshift. The mRNA level of betP, proP and lcoP was strongly reduced or undetectable in the mutant, whereas that of mscL (mechanosensitive channel) was increased. The changes in cell morphology, antibiotics susceptibility and the mRNA levels of betP, proP, lcoP, mscL and mepA could be reversed by expression of plasmid-encoded copies of mtrAB in the DeltamtrAB mutant, confirming that these changes occurred as a consequence of the mtrAB deletion.
...
PMID:Deletion of the genes encoding the MtrA-MtrB two-component system of Corynebacterium glutamicum has a strong influence on cell morphology, antibiotics susceptibility and expression of genes involved in osmoprotection. 1546 14

Leukocytes synthesize a variety of inflammatory mediators that are packaged and stored in the cytoplasm within membrane-bound granules. Upon stimulation, the cells secrete the granule contents via an exocytotic process whereby the granules translocate to the cell periphery, the granule membranes fuse with the plasma membrane, and the granule contents are released extracellularly. We have reported previously that another exocytotic process, release of mucin by secretory cells of the airway epithelium, is regulated by the myristoylated alanine-rich C kinase substrate (MARCKS) (Li Y, Martin LD, Spizz G, Adler KB. MARCKS protein is a key molecule regulating mucin secretion by human airway epithelial cells in vitro. J Biol Chem 2001;276:40982-40990; Singer M, Martin LD, Vargaftig BB, Park J, Gruber AD, Li Y, Adler KB. A MARCKS-related peptide blocks mucus hypersecretion in a mouse model of asthma. Nat Med 2004;10:193-196). In those studies, mucin secretion in vitro and in vivo was attenuated by a synthetic peptide identical to the N-terminus of MARCKS, named the MANS peptide (Li and colleagues, 2001). In this study, we used the MANS peptide to investigate possible involvement of MARCKS in secretion of leukocyte granule proteins. In neutrophils isolated from human blood, phorbol 12-myristate 13-acetate-induced myeloperoxidase release was attenuated in a concentration-dependent manner by MANS but not by equal concentrations of a missense control peptide. In additional studies using human leukocyte cell lines, secretion of eosinophil peroxidase from the eosinophil-like cell line HL-60 clone 15, lysozyme from the monocytic leukemia cell line U937, and granzyme from the lymphocyte natural killer cell line NK-92 were attenuated by preincubation of the cells with MANS but not with the missense control peptide. The results indicate that MARCKS protein may play an important role in the secretion of membrane-bound granules from different leukocytes. MARCKS may be an important component of secretory pathways associated with release of granules by different cell types.
...
PMID:A peptide against the N-terminus of myristoylated alanine-rich C kinase substrate inhibits degranulation of human leukocytes in vitro. 1654 3

In competent Bacillus subtilis, the ComG proteins are required to allow exogenous DNA to access to membrane-bound receptor ComEA during transformation. Here we describe a multimeric complex containing the pilin-like protein ComGC. Due to similarities to the type 4 pilus and the type 2 secretion system pseudopilus, we have tentatively named it the "competence pseudopilus." The ComGC multimer is released from cells upon digestion of the cell wall with lysozyme and has a heterogeneous size, estimated to range between 40 and 100 monomers, covalently linked by disulfide bonds. We determined that the prepilin peptidase ComC, the thiol-disulfide oxidoreductase pair BdbDC, and all seven ComG proteins are necessary to form the pseudopilus. Furthermore, these proteins are also sufficient to form a functional complex, i.e. able to facilitate binding of exogenous DNA to ComEA. The initial steps of pseudopilus biogenesis include the processing of ComGC in the cytoplasmic membrane and consist of two independent events, proteolytic cleavage by ComC and formation of an intramolecular disulfide bond by BdbDC. The other ComG proteins are required to assemble the mature ComGC monomers in the membrane into a multimeric complex proposed to span the cell envelope. We discuss the possible role of the competence pseudopilus in DNA binding and uptake during transformation.
...
PMID:A macromolecular complex formed by a pilin-like protein in competent Bacillus subtilis. 1675 Nov 95

The applicability of the two newly commercial available squaraine labels Square-670-NHS and Seta-635-NHS to exploring protein-lipid interactions has been evaluated. The labels were conjugated to lysozyme (Lz) (squaraine-lysozyme conjugates below referred to as Square-670-Lz and Seta-635-Lz), a structurally well-characterized small globular protein displaying the ability to interact both, electrostatically and hydrophobically with lipids. The lipid component of the model systems was represented by lipid vesicles composed of zwitterionic lipids egg yolk phosphatidylcholine (PC) and 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), and their mixtures with anionic lipids either beef heart cardiolipin (CL) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), respectively. Fluorescence intensity of Square-670-Lz was found to decrease upon association with lipid bilayer, while the fluorescence intensity of Seta-635-Lz displayed more complex behavior depending on lipid-to-protein molar ratio. Covalent coupling of squaraine labels to lysozyme exerts different influence on the properties of dye-protein conjugate. It was suggested that Square-670-NHS covalent attachment to Lz molecule enhances protein propensity for self-association, while squaraine label Seta-635-NHS is sensitive to different modes of lysozyme-lipid interactions-within the L:P range 6-11, when hydrophobic protein-lipid interactions are predominant, an aggregation of membrane-bound protein molecules takes place, thereby decreasing the fluorescence intensity of Seta-635-Lz. At higher L:P values (from 22 to 148) when electrostatic interactions are enhanced fluorescence intensity of Seta-635-Lz increases with increasing lipid concentrations.
...
PMID:Tracing lysozyme-lipid interactions with long-wavelength squaraine dyes. 1719 21

Biological functions of lysozyme, including its antimicrobial, antitumor, and immune-modulatory activities have been suggested to be largely determined by the lipid binding properties of this protein. To gain further insight into these interactions on a molecular level the association of lysozyme to liposomes composed of either 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine or its mixtures with 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-glycerol, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-phosphatidylserine, or bovine heart cardiolipin was studied by a combination of fluorescence techniques. The characteristics of the adsorption of lysozyme to lipid bilayers were investigated using fluorescein 5'-isothiocyanate labeled protein, responding to membrane association by a decrease in fluorescence. Upon increasing the content of anionic phospholipids in lipid vesicles, the binding isotherms changed from Langmuir-like to sigmoidal. Using adsorption models based on scaled particle and double-layer theories, this finding was rationalized in terms of self-association of the membrane-bound protein. The extent of quenching of lysozyme tryptophan fluorescence by acrylamide decreased upon membrane binding, revealing a conformational transition for the protein upon its surface association, resulting in a diminished access of the fluorophore to the aqueous phase. Steady-state fluorescence anisotropy of bilayer-incorporated probe 1,6-diphenyl-1,3,5-hexatriene was measured at varying lipid-to-protein molar ratios. Lysozyme was found to increase acyl-chain order for liposomes with the content of acidic phospholipid exceeding 10 mol %. Both electrostatic and hydrophobic protein-lipid interactions can be concluded to modulate the aggregation behavior of lysozyme when bound to lipid bilayers. Modulation of lysozyme aggregation propensity by membrane binding may have important implications for protein fibrillogenesis in vivo. Disruption of membrane integrity by the aggregated protein species is likely to be the mechanism responsible for the cytotoxicity of lysozyme.
...
PMID:Binding of lysozyme to phospholipid bilayers: evidence for protein aggregation upon membrane association. 1743 39

Extensive studies have been performed in order to understand the interaction of receptors with soluble ligands. However, we know very little of the parameters that regulate the interaction of receptors with membrane-bound ligands. Artificial lipid bilayers can be used to mimic cell-to-cell interactions, but a major challenge remains how to tether molecules to these membranes. We describe a simple and reliable method to tether ligands on glass-supported artificial bilayers containing biotinylated lipids. In this system, the model antigen hen egg lysozyme (HEL) is tethered through a fluorescently labeled streptavidin-monobiotinylated anti-HEL antibody bridge. This allows us to study the interaction of HEL-specific B cells with the tethered antigen by a variety of microscopy techniques. We recently used this system to study the activation of B cells by membrane antigens.
...
PMID:Studying cell-to-cell interactions: an easy method of tethering ligands on artificial membranes. 1916 Jun 66

Invertebrate (I-) type lysozymes, like all other known lysozymes, are dedicated to the hydrolysis of peptidoglycan, the major bacterial cell wall polymer, thereby contributing to the innate immune system and/or digestive system of invertebrate organisms. Bacteria on the other hand have developed several protective strategies against lysozymes, including the production of periplasmic and/or membrane-bound lysozyme inhibitors. The latter have until now only been described for chicken (C-) type lysozymes. We here report the discovery, purification, identification and characterization of the first bacterial specific I-type lysozyme inhibitor from Aeromonas hydrophila, which we designate PliI (periplasmic lysozyme inhibitor of the I-type lysozyme). PliI has homologs in several proteobacterial genera and contributes to I-type lysozyme tolerance in A. hydrophila in the presence of an outer membrane permeabilizer. These and previous findings on C-type lysozyme inhibitors suggest that bacterial lysozyme inhibitors may have an important function, for example, in bacteria-host interactions.
...
PMID:Lysozyme inhibitor conferring bacterial tolerance to invertebrate type lysozyme. 2004 5

RcsF, a proposed auxiliary regulator of the regulation of capsule synthesis (rcs) phosphorelay system, is a key element for understanding the RcsC-D-A/B signaling cascade, which is responsible for the regulation of more than 100 genes and is involved in cell division, motility, biofilm formation, and virulence. The RcsC-D-A/B system is one of the most complex bacterial signal transduction pathways, consisting of several membrane-bound and soluble proteins. RcsF is a lipoprotein attached to the outer membrane and plays an important role in activating the RcsC-d-A/B pathway. The exact mechanism of activation of the rcs phosphorelay by RcsF, however, remains unknown. We have analyzed the sequence of RcsF and identified three structural elements: 1) an N-terminal membrane-anchored helix (residues 3-13), 2) a loop (residues 14-48), and 3) a C-terminal folded domain (residues 49-134). We have determined the structure of this C-terminal domain and started to investigate its interaction with potential partners. Important features of its structure are two disulfide bridges between Cys-74 and Cys-118 and between Cys-109 and Cys-124. To evaluate the importance of this RcsF disulfide bridge network in vivo, we have examined the ability of the full-length protein and of specific Cys mutants to initiate the rcs signaling cascade. The results indicate that the Cys-74/Cys-118 and the Cys-109/Cys-124 residues correlate pairwise with the activity of RcsF. Interaction studies showed a weak interaction with an RNA hairpin. However, no interaction could be detected with reagents that are believed to activate the rcs phosphorelay, such as lysozyme, glucose, or Zn(2+) ions.
...
PMID:A disulfide bridge network within the soluble periplasmic domain determines structure and function of the outer membrane protein RCSF. 2147 Nov 96

We describe an integrated method for solid-phase protein PEGylation and the purification of mono-PEGylated protein thus synthesized. Lysozyme was used as model protein in this study. Methoxy-polyethyleneglycol propionaldehyde (or m-PEG propionaldehyde) was first immobilized on a stack of microporous hydrophobic interaction membranes housed in a module. The membrane-bound m-PEG propionaldehyde was then contacted with lysozyme solution, which also contained sodium cyanoborohydride as a reducing agent. The PEGylated lysozyme thus synthesized remained attached to the membrane, whereas unreacted protein could easily be removed from the module. PEGylated protein was then eluted from the membrane in a partially purified form using salt-free buffer. Two separate steps were thus integrated into a single process: protein PEGylation, followed by purification of mono-PEGylated protein. This solid-phase method is likely to be suitable for PEGylating any protein because it is based on the immobilization of the activated PEG and not the protein being PEGylated.
...
PMID:Integrated solid-phase synthesis and purification of PEGylated protein. 2165 27

Most human transfusion recipients fail to make detectable alloantibodies to foreign RBC antigens ("nonresponders"). Herein, we use a murine model to test the hypothesis that nonresponders may be immunologically tolerant. FVB mice transfused with RBCs expressing transgenic human glycophorin A (hGPA) antigen in the absence of inflammation produced undetectable levels of anti-hGPA immunoglobulins, unlike those transfused in the presence of polyinosinic:polycytidylic acid-induced inflammation. Mice in the nonresponder group failed to produce anti-hGPA after subsequent transfusions in the presence of polyinosinic:polycytidylic acid, whereas anti-hGPA levels increased in the responder group. This tolerance was antigen specific, because nonresponders to hGPA produced alloantibodies to RBCs that expressed a different transgenic antigen. This tolerance was not an idiosyncrasy of the hGPA antigen nor of the recipient strain, because B10.BR mice transfused with membrane-bound hen egg lysozyme antigen-transgenic RBCs also demonstrated induced nonresponsiveness. These data demonstrate that RBCs transfused in the absence of inflammation can induce tolerance.
...
PMID:Transfusion in the absence of inflammation induces antigen-specific tolerance to murine RBCs. 2232 8


<< Previous 1 2 3 4 5 6 7 8 9 Next >>

---