ABSTRACT
In this review the mechanisms of protein folding, misfolding, and aggregation as well as the mechanisms of cell defense against toxic protein aggregates are considered. Misfolded and aggregated proteins in cells are exposed to chaperone-mediated refolding and are degraded by proteasomes if refolding is impossible. Proteolysis-stable protein aggregates accumulate, forming inclusion bodies. In eucaryotic cells, protein aggregates form structures in the pericentrosomal area that have been termed "aggresomes". Formation of aggresomes in cells is a general cellular response to the presence of misfolded proteins when the degrading capacity of the cells is exceeded. The role of aggresomes in disturbance of the proteasomal system operation and in cellular death, particularly in the so-called "protein conformational diseases", is discussed.
Subject(s)
Centrosome/metabolism , Inclusion Bodies/metabolism , Macromolecular Substances/metabolism , Protein Folding , Proteins/metabolism , Animals , Humans , Kinetics , Models, Biological , Molecular Chaperones/chemistry , Molecular Chaperones/metabolismABSTRACT
This review presents findings on a new family of antibacterial proline-rich oligopeptides--pyrrhocoricin, drosocin, apidaecin, and formaecin--isolated from insects. The functional and physicochemical properties of proline-rich oligopeptides are considered, a role of proline in their antibacterial activity is discussed, and experimental evidence is given in favor of the ability of these oligopeptides to suppress metabolism of bacteria by means of stereospecific interaction with heat shock protein DnaK and inhibition of DnaK-dependent protein folding. Binding of the peptides under investigation with DnaK correlates with their antibacterial activity. Evidence that pyrrhocoricin, drosocin, apidaecin, and formaecin are nontoxic for human and animal cells serves as a prerequisite for their use as novel antibiotic drugs.
Subject(s)
Oligopeptides/pharmacology , Proteins/antagonists & inhibitors , Adenosine Triphosphatases/physiology , Amino Acid Sequence , Amino Acids/physiology , Anti-Bacterial Agents/metabolism , Anti-Bacterial Agents/pharmacology , Escherichia coli/drug effects , Escherichia coli/genetics , Escherichia coli/metabolism , Escherichia coli Proteins/physiology , HSP70 Heat-Shock Proteins/physiology , Molecular Chaperones/physiology , Protein Folding , Proteins/metabolismABSTRACT
This review summarizes findings on a new family of small cytoplasmic proteins called copper chaperones. The copper chaperones bind and deliver copper ions to intracellular compartments and insert the copper into the active sites of specific partners, copper-dependent enzymes. Three types of copper chaperones have been found in eukaryotes. Their three-dimensional structures have been determined, intracellular target proteins identified, and mechanisms of action have been revealed. The Atx1 copper chaperone binds Cu(I) and interacts directly with the copper-binding domains of a P-type ATPase copper transporter, its physiological partner. The copper chaperone CCS delivers Cu(I) to Cu,Zn-superoxide dismutase 1. Cox17 and Cox11 proteins serve as copper chaperones for cytochrome c oxidase, a copper-dependent enzyme.
Subject(s)
Copper/metabolism , Molecular Chaperones/metabolism , Animals , Carrier Proteins/metabolism , Cation Transport Proteins/metabolism , Copper Transport Proteins , Electron Transport Chain Complex Proteins , Electron Transport Complex IV/metabolism , Humans , Membrane Proteins/metabolism , Mitochondrial Proteins , Models, Molecular , Protein Transport/physiology , Saccharomyces cerevisiae Proteins/metabolism , Superoxide Dismutase/metabolismABSTRACT
Vanadyl ions may be used for reactivation of apodopamine beta-monooxygenase. Maximal activity of the enzyme was achieved at a 350-400-fold molar excess of vanadyl ions, whereas for maximal reconstitution with copper, an 8-10-fold molar excess of copper was necessary. AT higher concentrations of vanadyl as well as of copper, inhibition was observed.
Subject(s)
Adrenal Medulla/enzymology , Apoenzymes/metabolism , Apoproteins/metabolism , Chromaffin Granules/enzymology , Chromaffin System/enzymology , Dopamine beta-Hydroxylase/metabolism , Enzyme Activation/drug effects , Enzyme Reactivators , Vanadates/pharmacology , Animals , Binding Sites , Cations, Divalent , Cattle , Copper/metabolism , Copper/pharmacology , Electron Spin Resonance Spectroscopy , Kinetics , Macromolecular Substances , Vanadates/metabolismABSTRACT
Secretory granules obtained from bovine pituitary, atrium and adrenal medulla contain an extremely acidic copper protein resembling by its main physico-chemical and antigenic properties as well as by the ability of its apoform to inhibit dopamine beta-monooxygenase the protein from brain, neurocuprein.
Subject(s)
Cytoplasmic Granules/ultrastructure , Metalloproteins/analysis , Adrenal Medulla/ultrastructure , Animals , Cattle , Chemical Phenomena , Chemistry, Physical , Dopamine beta-Hydroxylase/antagonists & inhibitors , Heart Atria/ultrastructure , Pituitary Gland/ultrastructureABSTRACT
Metallothionein saturated with copper is able to donate copper to apodopamine beta-monooxygenase. The complete recovery of dopamine beta-monooxygenase activity is observed at the molar ratio Cu-thionein/apoenzyme of 25. On the other hand, apothionein accepts copper easily from the holoenzyme.
Subject(s)
Copper/metabolism , Dopamine beta-Hydroxylase/metabolism , Metallothionein/metabolism , Adrenal Medulla/enzymology , Animals , Cattle , Chromatography, Gel , Enzyme Activation , KineticsABSTRACT
The apoform of neurocuprein, the copper protein from brain and chromaffin granules, was found to be a potent inhibitor of the hydroxylating activity of dopamine beta-monooxygenase, whereas the holoform of neurocuprein has no effect on the activity of the enzyme. The inhibiting capacity of neurocuprein may be due to the property of the apoprotein to chelate copper from the enzyme. A role of neurocuprein as an endogenous protein regulator of dopamine beta-monooxygenase is suggested.
Subject(s)
Apoproteins/pharmacology , Dopamine beta-Hydroxylase/antagonists & inhibitors , Metalloproteins/pharmacology , Animals , Brain Chemistry , Catechols/metabolism , Cattle , Chromaffin Granules/analysis , Copper/metabolism , Dose-Response Relationship, Drug , Oxygen Consumption/drug effects , Structure-Activity Relationship , Tyramine/metabolismABSTRACT
Nitrite inhibits the oxygen uptake by the system ferrocytochrome c-cytochrome oxidase with Ki = 1.5 mM. In the absence of ferrocytochrome c the oxygen uptake by cytochrome oxidase in the presence of nitrite was observed indicating that the enzyme has some nitrite oxidase activity. Nitrite induces changes in optical difference spectra of cytochrome oxidase and, in particular, the formation of the transient band at 607 nm. The reciprocal relation was observed between the intensity of this band and the rate of the oxygen uptake by cytochrome oxidase. This means that the form of the enzyme with this band does not involved in the nitrite oxidase activity. It is suggested that the nitrite oxidase activity relates to the oxygen binding site rather than the cytochrome c binding site of the enzyme.
Subject(s)
Electron Transport Complex IV/antagonists & inhibitors , Nitrites/pharmacology , Animals , Cattle , Cytochrome c Group/metabolism , Kinetics , Mitochondria, Heart/enzymology , Oxygen Consumption/drug effects , Protein Binding , SpectrophotometryABSTRACT
Under aerobic conditions hydrazine reduces haem a of cardiac cytochrome oxidase and brings about the formation in optical spectra of a new band at 845 nm, whereas under anaerobic conditions hydrazine reduces both haems, a and a3, as well as EPR-detectable copper, CuA, and results in the band at 845 nm. The formation of this band was sensitive to inhibitors of oxygen binding. It is suggested that the band at 845 nm reflects changes induced by hydrazine in CuB which in the resting enzyme is EPR-undetectable.
