scholarly journals Copper binding to the N-terminal metal-binding sites or the CPC motif is not essential for copper-induced trafficking of the human Wilson protein (ATP7B)

2006 ◽  
Vol 401 (1) ◽  
pp. 143-153 ◽  
Author(s):  
Michael A. Cater ◽  
Sharon La fontaine ◽  
Julian F. B. Mercer
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Site Directed Mutagenesis ◽  
Copper Binding ◽  
Phosphatase Domain ◽  
Copper Chelation ◽  
Metal Binding Sites ◽  
Excess Copper ◽  
Wilson Protein ◽  
P Type

The Wilson protein (ATP7B) is a copper-translocating P-type ATPase that mediates the excretion of excess copper from hep-atocytes into bile. Excess copper causes the protein to traffic from the TGN (trans-Golgi network) to subapical vesicles. Using site-directed mutagenesis, mutations known or predicted to abrogate catalytic activity (copper translocation) were introduced into ATP7B and the effect of these mutations on the intracellular traf-ficking of the protein was investigated. Mutation of the critical aspartic acid residue in the phosphorylation domain (DKTGTIT) blocked copper-induced redistribution of ATP7B from the TGN, whereas mutation of the phosphatase domain [TGE (Thr-Gly-Glu)] trapped ATP7B at cytosolic vesicular compartments. Our findings demonstrate that ATP7B trafficking is regulated with its copper-translocation cycle, with cytosolic vesicular localization associated with the acyl-phosphate intermediate. In addition, mut-ation of the six N-terminal metal-binding sites and/or the trans-membrane CPC (Cys-Pro-Cys) motif did not suppress the consti-tutive vesicular localization of the ATP7B phosphatase domain mutant. These results suggested that copper co-ordination by these sites is not essential for trafficking. Importantly, copper-chelation studies with these mutants clearly demonstrated a requirement for copper in ATP7B trafficking, suggesting the presence of an additional copper-binding site(s) within the protein. The results presented in this report significantly advance our understanding of the regulatory mechanism that links copper-translocation activity with copper-induced intracellular trafficking of ATP7B, which is central to hepatic and hence systemic copper homoeostasis.

scholarly journals Intracellular trafficking of the human Wilson protein: the role of the six N-terminal metal-binding sites

2004 ◽  
Vol 380 (3) ◽  
pp. 805-813 ◽  
Author(s):  
Michael A. CATER ◽  
John FORBES ◽  
Sharon La FONTAINE ◽  
Diane COX ◽  
Julian F. B. MERCER
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Intracellular Trafficking ◽  
Copper Toxicity ◽  
Site Directed Mutagenesis ◽  
Metal Binding Sites ◽  
Wilson Protein ◽  
Necessary And Sufficient ◽  
Golgi Network

The Wilson protein (ATP7B) is a copper-transporting CPx-type ATPase defective in the copper toxicity disorder Wilson disease. In hepatocytes, ATP7B delivers copper to apo-ceruloplasmin and mediates the excretion of excess copper into bile. These distinct functions require the protein to localize at two different subcellular compartments. At the trans-Golgi network, ATP7B transports copper for incorporation into apo-ceruloplasmin. When intracellular copper levels are increased, ATP7B traffics to post-Golgi vesicles in close proximity to the canalicular membrane to facilitate biliary copper excretion. In the present study, we investigated the role of the six N-terminal MBSs (metal-binding sites) in the trafficking process. Using site-directed mutagenesis, we mutated or deleted various combinations of the MBSs and assessed the effect of these changes on the localization and trafficking of ATP7B. Results show that the MBSs required for trafficking are the same as those previously found essential for the copper transport function. Either MBS 5 or MBS 6 alone was sufficient to support the redistribution of ATP7B to vesicular compartments. The first three N-terminal motifs were not required for copper-dependent intracellular trafficking and could not functionally replace sites 4–6 when placed in the same sequence position. Furthermore, the N-terminal region encompassing MBSs 1–5 (amino acids 64–540) was not essential for trafficking, with only one MBS close to the membrane channel, necessary and sufficient to support trafficking. Our findings were similar to those obtained for the closely related ATP7A protein, suggesting similar mechanisms for trafficking between copper-transporting CPx-type ATPases.

Protein engineering of xylose (glucose) isomerase from Actinoplanes missouriensis. 1. Crystallography and site-directed mutagenesis of metal binding sites

Biochemistry ◽  
1992 ◽  
Vol 31 (24) ◽  
pp. 5449-5458 ◽  
Author(s):  
John Jenkins ◽  
Joel Janin ◽  
Felix Rey ◽  
Mohammed Chiadmi ◽  
Herman Van Tilbeurgh ◽  
...  
Keyword(s):  
Protein Engineering ◽  
Metal Binding ◽  
Binding Sites ◽  
Glucose Isomerase ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Metal Binding Sites

scholarly journals Comparison of the sedimentation and gel-filtration behaviour of human apotransferrin and its copper and iron complexes

1973 ◽  
Vol 133 (4) ◽  
pp. 749-754 ◽  
Author(s):  
Peter A. Charlwood
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Equilibrium Dialysis ◽  
Gel Filtration ◽  
Sedimentation Velocity ◽  
Copper Binding ◽  
Metal Binding Sites ◽  
Stokes Radius ◽  
Effect Of Copper ◽  
Specific Metal

Equilibrium-dialysis experiments showed that Tris or citrate in the solution prevented copper from occupying completely the specific metal-binding sites on human transferrin. Differential measurements of sedimentation velocity under conditions where two atoms of copper per molecule of protein were bound showed an increase in s020,w, relative to that of the apoprotein, practically the same as that produced by two atoms of iron. Gel-filtration experiments made under the same conditions to investigate the effect of copper binding on the Stokes radius of the protein showed merely that it lost most of the metal as it passed down the column.

scholarly journals Escherichia coli inorganic pyrophosphatase : site-directed mutagenesis of the metal binding sites

FEBS Letters ◽  
1996 ◽  
Vol 399 (1-2) ◽  
pp. 99-102 ◽  
Author(s):  
Svetlana Avaeva ◽  
Pavel Ignatov ◽  
Svetlana Kurilova ◽  
Tatjana Nazarova ◽  
Elena Rodina ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Metal Binding ◽  
Binding Sites ◽  
Site Directed Mutagenesis ◽  
Inorganic Pyrophosphatase ◽  
Directed Mutagenesis ◽  
Metal Binding Sites

scholarly journals Rational design of metal-binding sites in domain-swapped myoglobin dimers

2021 ◽  
Vol 217 ◽  
pp. 111374
Author(s):  
Satoshi Nagao ◽  
Ayaka Idomoto ◽  
Naoki Shibata ◽  
Yoshiki Higuchi ◽  
Shun Hirota
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Rational Design ◽  
Metal Binding Sites

scholarly journals Electron transfer pathways in photoexcited lanthanide(III) complexes of picolinate ligands

2021 ◽  
Author(s):  
Daniel Kovacs ◽  
Daniel Kocsi ◽  
Jordann A. L. Wells ◽  
Salauat R. Kiraev ◽  
Eszter Borbas
Keyword(s):  
Electron Transfer ◽  
Metal Binding ◽  
Binding Sites ◽  
Secondary Amide ◽  
Metal Binding Sites ◽  
Electron Transfer Pathways

A series of luminescent lanthanide(III) complexes consisting of 1,4,7-triazacyclononane frameworks and three secondary amide-linked carbostyril antennae were synthesised. The metal binding sites were augmented with two pyridylcarboxylate donors yielding octadentate...

scholarly journals Machine learning differentiates enzymatic and non-enzymatic metals in proteins

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ryan Feehan ◽  
Meghan W. Franklin ◽  
Joanna S. G. Slusky
Keyword(s):  
Machine Learning ◽  
Metal Binding ◽  
Binding Sites ◽  
Active Sites ◽  
De Novo ◽  
Enzyme Design ◽  
Metal Binding Sites ◽  
Ensemble Machine Learning ◽  
Machine Learning Model ◽  
Physicochemical Features

AbstractMetalloenzymes are 40% of all enzymes and can perform all seven classes of enzyme reactions. Because of the physicochemical similarities between the active sites of metalloenzymes and inactive metal binding sites, it is challenging to differentiate between them. Yet distinguishing these two classes is critical for the identification of both native and designed enzymes. Because of similarities between catalytic and non-catalytic  metal binding sites, finding physicochemical features that distinguish these two types of metal sites can indicate aspects that are critical to enzyme function. In this work, we develop the largest structural dataset of enzymatic and non-enzymatic metalloprotein sites to date. We then use a decision-tree ensemble machine learning model to classify metals bound to proteins as enzymatic or non-enzymatic with 92.2% precision and 90.1% recall. Our model scores electrostatic and pocket lining features as more important than pocket volume, despite the fact that volume is the most quantitatively different feature between enzyme and non-enzymatic sites. Finally, we find our model has overall better performance in a side-to-side comparison against other methods that differentiate enzymatic from non-enzymatic sequences. We anticipate that our model’s ability to correctly identify which metal sites are responsible for enzymatic activity could enable identification of new enzymatic mechanisms and de novo enzyme design.

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