Mass spectrometric studies of Cu(I)-binding to the N-terminal domains of B. subtilis CopA and influence of bacillithiol

CopA is a Cu(I)-exporting transmembrane P1B-type ATPase from Bacillus subtilis. Electrospray ionisation mass spectrometric analysis of Cu(I)-binding to the N-terminal domains of CopA (CopAab) reveals formation of a dimeric form, Cu6(CopAab)2, at >1 Cu(I)/protein. Dimeric forms persist in the presence of bacillithiol.72