Mutational analysis of the Menkes copper P-type ATPase (ATP7A).
The Menkes protein (ATP7A; MNK) is a ubiquitous human copper-translocating P-type ATPase and it has a key role in regulating copper homeostasis. Previously we characterised fundamental steps in the catalytic cycle of the Menkes protein. In this study we analysed the role of several conserved regions of the Menkes protein, particularly within the putative cytosolic ATP-binding domain. The results of catalytic studies have indicated an important role of 1086His in catalysis. Our findings provide a biochemical explanation for the most common Wilson disease-causing mutation (H1069Q in the homologous Wilson copper-translocating P-type ATPase). Furthermore, we have identified a unique role of 1230Asp, within the DxxK motif, in coupling ATP binding and acylphosphorylation with copper translocation. Finally, we found that the Menkes protein mutants with significantly reduced catalytic activity can still undergo copper-regulated exocytosis, suggesting that only the complete loss of catalytic activity prevents copper-regulated trafficking of the Menkes protein.
Voskoboinik
I
I
Department of Genetics, The University of Melbourne, Victoria 3010, Australia.
Mar
J
J
Camakaris
J
J
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D000073840:Copper-Transporting ATPases; D006224:Cricetinae; D006527:Hepatolenticular Degeneration / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D021381:Protein Transport / Q000502:physiology; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D027682:Cation Transport Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D003300:Copper; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C081184:ATP7A protein, human; D000073840:Copper-Transporting ATPases