Backbone resonance assignments of the homotetrameric (48 kD) copper sensor CsoR from Geobacillus thermodenitrificans in the apo- and Cu(I)-bound states: insights into copper-mediated allostery.

Prokaryotes are highly susceptible to exogenous copper and employ metalloregulatory proteins to control the intracellular concentration. CsoR (copper-sensitive operon repressor) is one such protein that represses transcription of a Cu(I)-effluxing ATPase in its apo form. Cu(I)-binding leads to transcriptional derepression and cellular copper resistance. Herein, we present substantially complete backbone (H(N), N, C', Cα, Cβ) resonance assignments of tetrameric (48 kD) Geobacillus thermodenitrificans (Gt) CsoR in its apo- and Cu(I)-saturated states. These data provide the first spectroscopic evidence that Cu(I)-binding induces an interruption in the long α2 helix of CsoR.