Chimeras of P-type ATPases and their transcriptional regulators: contributions of a cytosolic amino-terminal domain to metal specificity.

Zn(2+)-responsive repressor ZiaR and Co(2+)-responsive activator CoaR modulate production of P(1)-type Zn(2+)- (ZiaA) and Co(2+)- (CoaT) ATPases respectively. What dictates metal selectivity? We show that Delta ziaDeltacoa double mutants had similar Zn(2+) resistance to Deltazia single mutants and similar Co(2+) resistance to Deltacoa single mutants. Controlling either ziaA or coaT with opposing regulators restored no resistance to metals sensed by the regulators, but coincident replacement of the deduced cytosolic amino-terminal domain CoaT(N) with ZiaA(N) (in ziaR-(p) ziaA-ziaA(N)coaT) conferred Zn(2+) resistance to DeltaziaDeltacoa, Zn(2+) content was lowered and residual Co(2+) resistance lost.

A copper metallochaperone for photosynthesis and respiration reveals metal-specific targets, interaction with an importer, and alternative sites for copper acquisition.

A bacterial two-hybrid assay revealed interaction between a protein now designated bacterial Atx1 and amino-terminal domains of copper-transporting ATPases CtaA (cellular import) and PacS (thylakoid import) but not the related zinc (ZiaA) or cobalt (CoaT) transporters from the same organism (Synechocystis PCC 6803). The specificity of metallochaperone interactions coincides with metal specificity. After reconstitution in a N(2) atmosphere, bacterial Atx1 bound 1 mol of copper mol(-1), and apoPacS(N) acquired copper from copper-Atx1.