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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Enterococcus hirae CopB ATPase (EC 3.6.1.3) confers copper resistance to the organism by expelling excess copper. Two related human ATPase genes, ATP7A (EC 3.6.1.36) and ATP7B (EC 3.6.1.36), have been cloned as the loci of mutations causing Menkes and Wilson diseases, diseases of copper metabolism. Many mutations in these genes have been identified in patients. Since it has not yet been possible to purify the human copper ATPases, it has proved difficult to test the impact of mutations on ATPase function. Some mutations occur in highly conserved sequence motifs, suggesting that their effect on function can be tested with a homologous enzyme. Here, we used the E. hirae CopB ATPase to investigate the impact of such mutations on enzyme function in vivo and in vitro. The Menkes disease mutation of Cys-1000-->Arg, changing the conserved Cys-Pro-Cys ('CPC') motif, was mimicked in CopB. The corresponding Cys-396-->Ser CopB ATPase was unable to restore copper resistance in a CopB knock-out mutant in vivo. The purified mutant ATPase still formed an acylphosphate intermediate, but possessed no detectable ATP hydrolytic activity. The most frequent Wilson disease mutation, His-1069-->Gln, was introduced into CopB as His-480-->Gln (H480Q). This mutant CopB also failed to confer copper resistance to a CopB knock-out strain. Purified H480Q CopB formed an acylphosphate intermediate and retained a small, but significant, ATPase activity. Our results reveal that Cys-396 and His-480 of CopB are key residues for ATPase function, and similar roles are suggested for Cys-1000 and His-1069 of Menkes and Wilson ATPases respectively.
...
PMID:Structure-function analysis of purified Enterococcus hirae CopB copper ATPase: effect of Menkes/Wilson disease mutation homologues. 1141 52

Escherichia coli CopA is a Cu(I)-translocating P-type ATPase that is involved in copper export and resistance. It is an orthologue of the human Menkes and Wilson disease-related proteins. Each of those two human copper pumps has six N-terminal Cys(X)(2)Cys sequences, but their function in transport is unclear. CopA has two N-terminal Cys(X)(2)Cys sequences, GLSC(14)GHC(17) and GMSC(110)ASC(113). The requirement of these cysteine motifs was investigated by mutagenesis of the codons for all four cysteine residues, singly and in combination. Cells of a copA deletion strain expressing genes for the mutant genes were nearly as resistant to copper as the wild type. In addition, everted membrane vesicles from cells expressing the mutant copA genes exhibited ATP-coupled accumulation of copper similar to that of the wild type. The results indicate that neither of two N-terminal Cys(X)(2)Cys motifs is required for either resistance or transport.
...
PMID:Escherichia coli CopA N-terminal Cys(X)(2)Cys motifs are not required for copper resistance or transport. 1150 54

In mammalian cells, mitochondria provide energy from aerobic metabolism. They play an important regulatory role in apoptosis, produce and detoxify free radicals, and serve as a cellular calcium buffer. Neurodegenerative disorders involving mitochondria can be divided into those caused by oxidative phosphorylation (OXPHOS) abnormalities either due to mitochondrial DNA (mtDNA) abnormalities, e.g., chronic external ophthalmoplegia, or due to nuclear mutations of OXPHOS proteins, e.g., complex I and II associated with Leigh syndrome. There are diseases caused by nuclear genes encoding non-OXPHOS mitochondrial proteins, such as frataxin in Friedreich ataxia (which is likely to play an important role in mitochondrial-cytosolic iron cycling), paraplegin (possibly a mitochondrial ATP-dependent zinc metalloprotease of the AAA-ATPases in hereditary spastic paraparesis), and possibly Wilson disease protein (an abnormal copper transporting ATP-dependent P-type ATPase associated with Wilson disease). Huntingon disease is an example of diseases with OXPHOS defects associated with mutations of nuclear genes encoding non-mitochondrial proteins such as huntingtin. There are also disorders with evidence of mitochondrial involvement that cannot as yet be assigned. These include Parkinson disease (where a complex I defect is described and free radicals are generated from dopamine metabolism), amyotrophic lateral sclerosis, and Alzheimer disease, where there is evidence to suggest mitochondrial involvement perhaps secondary to other abnormalities.
...
PMID:Mitochondria and degenerative disorders. 1157 22

Copper-transporting ATPase ATP7B is essential for normal distribution of copper in human cells. Mutations in the ATP7B gene lead to copper accumulation in a number of tissues and to a severe multisystem disorder, known as Wilson's disease. Primary sequence analysis suggests that the copper-transporting ATPase ATP7B or the Wilson's disease protein (WNDP) belongs to the large family of cation-transporting P-type ATPases, however, the detailed characterization of its enzymatic properties has been lacking. Here, we developed a baculovirus-mediated expression system for WNDP, which permits direct and quantitative analysis of catalytic properties of this protein. Using this system, we provide experimental evidence that WNDP has functional properties characteristic of a P-type ATPase. It forms a phosphorylated intermediate, which is sensitive to hydroxylamine, basic pH, and treatments with ATP or ADP. ATP stimulates phosphorylation with an apparent K(m) of 0.95 +/- 0.25 microm; ADP promotes dephosphorylation with an apparent K(m) of 3.2 +/- 0.7 microm. Replacement of Asp(1027) with Ala in a conserved sequence motif DKTG abolishes phosphorylation in agreement with the proposed role of this residue as an acceptor of phosphate during the catalytic cycle. Catalytic phosphorylation of WNDP is inhibited by the copper chelator bathocuproine; copper reactivates the bathocuproine-treated WNDP in a specific and cooperative fashion confirming that copper is required for formation of the acylphosphate intermediate. These studies establish the key catalytic properties of the ATP7B copper-transporting ATPase and provide a foundation for quantitative analysis of its function in normal and diseased cells.
...
PMID:Functional properties of the copper-transporting ATPase ATP7B (the Wilson's disease protein) expressed in insect cells. 1167 46

Tetrathiomolybdate (TTM) avidly interacts with copper and has recently been employed to reduce excess copper in patients with Wilson disease. We found that TTM inhibits the purified Enterococcus hirae CopB copper ATPase with an IC(50) of 34 nM. Dithiomolybdate and trithiomolybdate, which commonly contaminate TTM, inhibited the copper ATPases with similar potency. Inhibition could be reversed by copper or silver, suggesting inhibition by substrate binding. These findings for the first time allowed an estimate of the high affinity of CopB for copper and silver. TTM is a new tool for the study of copper ATPases.
...
PMID:Tetrathiomolybdate inhibition of the Enterococcus hirae CopB copper ATPase. 1169 73

Mutations in the Wilson disease copper transporting, P-type ATPase lead to the accumulation of toxic levels of copper in the liver, brain, and kidney causing extensive tissue damage and eventual death. The NH(2)-terminal domain ( approximately 70 kDa), which contains six copies of the heavy metal-associated repeat GMT/HCXXC, is also able to bind zinc. We have used circular dichroism (CD) and x-ray absorption spectroscopy (XAS) to characterize zinc binding to the NH(2)-terminal metal-binding domain. These studies have revealed that zinc is able to bind to this domain with a stoichiometry of 6:1, and upon binding, induces conformational changes in the NH(2)-terminal domain. These conformational changes are completely different from those previously observed for copper binding to the domain and lead to an overall loss of secondary structure in the domain. The XAS spectra indicate that zinc is ligated primarily by nitrogen atoms and therefore has low affinity for the heavy metal-associated repeats where copper has been shown to bind. The differences between zinc and copper binding may serve as the basis for the metal-ion mediated regulation of the ATPase in vivo.
...
PMID:Zinc binding to the NH2-terminal domain of the Wilson disease copper-transporting ATPase: implications for in vivo metal ion-mediated regulation of ATPase activity. 1182 63

ZntA, a bacterial zinc-transporting P-type ATPase, is homologous to two human ATPases mutated in Menkes and Wilson diseases. To explore the roles of the bacterial ATPase residues homologous to those involved in the human diseases, we have introduced several point mutations into ZntA. The mutants P401L, D628A and P634L correspond to the Wilson disease mutations P992L, D1267A and P1273L, respectively. The mutations D628A and P634L are located in the C-terminal part of the phosphorylation domain in the so-called hinge motif conserved in all P-type ATPases. P401L resides near the N-terminal portion of the phosphorylation domain whereas the mutations H475Q and P476L affect the heavy metal ATPase-specific HP motif in the nucleotide binding domain. All mutants show reduced ATPase activity corresponding 0-37% of the wild-type activity. The mutants P401L, H475Q and P476L are poorly phosphorylated by both ATP and P(i). Their dephosphorylation rates are slow. The D628A mutant is inactive and cannot be phosphorylated at all. In contrast, the mutant P634L six residues apart in the same domain shows normal phosphorylation by ATP. However, phosphorylation by P(i) is almost absent. In the absence of added ADP the P634L mutant dephosphorylates much more slowly than the wild-type, whereas in the presence of ADP the dephosphorylation rate is faster than that of the wild-type. We conclude that the mutation P634L affects the conversion between the states E1P and E2P so that the mutant favors the E1 or E1P state.
...
PMID:Introducing Wilson disease mutations into the zinc-transporting P-type ATPase of Escherichia coli. The mutation P634L in the 'hinge' motif (GDGXNDXP) perturbs the formation of the E2P state. 1187 74

Mutations in the Wilson disease gene ATP7B, a P-type ATPase, are responsible for copper accumulation in the liver and other organs leading to Wilson disease (WD, OMIM 277900). Clinical manifestations of Wilson disease (WD) include chronic liver disease, acute hepatic failure or neuropsychiatric diseases. Since potent medical treatments are available to prevent disabling residual symptoms, early diagnosis is crucial. To demonstrate the clinical course and genetic findings, a male patient with a novel mutation in the ATP7B gene, a 10 base pair insertion in exon 6 (1927ins 10), and a second missense mutation in exon 13 (P992L) is reported. The patient presented with signs of chronic liver disease at the age of 10 years. Clinical findings included hepatomegaly, elevated liver enzymes and coagulopathy. A combination treatment with the copper chelating agent D-penicillamine and zinc acetate was started leading to normalization of liver function and no appearance of neurological signs or Kayser-Fleischer ring after 7 years follow-up. Truncating mutations of the ATP7B gene (insertions, deletions, nonsense mutations) leading to gross loss of C-terminal parts of the protein, thereby probably completely destroying the protein function, may correlate with a hepatic phenotype and early onset as seen in the patient presented.
...
PMID:Disturbed copper transport in humans. Part 2: mutations of the ATP7B gene lead to Wilson disease (WD). 1193 61

Copper is essential for the growth and development of mammalian cells. The key role in the intracellular distribution of copper belongs to the recently discovered family of metallochaperones and to copper-transporting P-type ATPases. The mutations in the ATPase ATP7B, the Wilson's disease protein (WNDP), lead to intracellular accumulation of copper and severe hepatic and neurological abnormalities. Several of these mutations were shown to disrupt the protein-protein interactions between WNDP and the metallochaperone Atox1, suggesting that these interactions are important for normal copper homeostasis. To understand the functional consequences of the Atox1-WNDP interaction at the molecular level, we produced recombinant Atox1 and characterized its effects on WNDP. We demonstrate that Atox1 transfers copper to the purified amino-terminal domain of WNDP (N-WNDP) in a dose-dependent and saturable manner. A maximum of six copper atoms can be transferred to N-WNDP by the chaperone. Furthermore, the incubation of copper Atox1 with the full-length WNDP leads to the stimulation of the WNDP catalytic activity, providing strong evidence for the direct effect of Atox1 on the function of this transporter. Our data also suggest that Atox1 can regulate the copper occupancy of WNDP. The incubation with apo-Atox1 results in the removal of copper from the metalated N-WNDP and apparent down-regulation of WNDP activity. Interestingly, at least one copper atom remains tightly bound to N-WNDP even in the presence of excess apo-Atox1. We suggest that this incomplete reversibility reflects the functional non-equivalency of the metal-binding sites in WNDP and speculate about the intracellular consequences of the reversible Atox1-mediated copper transfer.
...
PMID:Metallochaperone Atox1 transfers copper to the NH2-terminal domain of the Wilson's disease protein and regulates its catalytic activity. 1202 94

The Menkes protein (MNK; ATP7A) is a copper-transporting P-type ATPase that is defective in the copper deficiency disorder, Menkes disease. MNK is localized in the trans-Golgi network and transports copper to enzymes synthesized within secretory compartments. However, in cells exposed to excessive copper, MNK traffics to the plasma membrane where it functions in copper efflux. A conserved feature of all P-type ATPases is the formation of an acyl-phosphate intermediate, which occurs as part of the catalytic cycle during cation transport. In this study we investigated the effect of mutations within conserved catalytic regions of MNK on intracellular localization and trafficking from the trans-Golgi network (TGN). Our findings suggest that mutations that block formation of the phosphorylated catalytic intermediate also prevent copper-induced relocalization of MNK from the TGN. Furthermore, mutations in the phosphatase domain, which resulted in hyperphosphorylation of MNK, caused constitutive trafficking from the TGN to the plasma membrane. A similar effect on trafficking was observed with a phosphatase mutation in the closely related copper ATPase, ATP7B, affected in Wilson disease. These findings suggest that the copper-induced trafficking of the Menkes and Wilson disease copper ATPases is associated with the phosphorylated intermediate that is formed during the catalysis of these pumps. Our findings describe a novel mechanism for regulating the subcellular location of a transport protein involving the recognition of intermediate conformations during catalysis.
...
PMID:Copper-regulated trafficking of the Menkes disease copper ATPase is associated with formation of a phosphorylated catalytic intermediate. 1222 38


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---