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ATP dependent charge movement in ATP7B Cu + ‐ATPase is demonstrated by pre‐steady state electrical measurements
Author(s) -
Tadini-Buoninsegni Francesco,
Bartolommei Gianluca,
Moncelli Maria Rosa,
Pilankatta Rajendra,
Lewis David,
Inesi Giuseppe
Publication year - 2010
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2010.10.029
Subject(s) - chemistry , atpase , copper , heterologous , enzyme , biophysics , transmembrane protein , biochemistry , biology , receptor , organic chemistry , gene
ATP7B is a copper dependent P‐type ATPase, required for copper homeostasis. Taking advantage of high yield heterologous expression of recombinant protein, we investigated charge transfer in ATP7B. We detected charge displacement within a single catalytic cycle upon ATP addition and formation of phosphoenzyme intermediate. We attribute this charge displacement to movement of bound copper within ATP7B. Based on specific mutations, we demonstrate that enzyme activation by copper requires occupancy of a site in the N‐terminus extension which is not present in other transport ATPases, as well as of a transmembrane site corresponding to the cation binding site of other ATPases.