RESUMO
When Hansenula anomala cells were treated by the combined addition of pyrithione, a zinc ionophore, and metal chelating agents such as EDTA and N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine, the antimycin A3-dependent induction of cyanide-resistant respiratory activity was suppressed. Among the chelators we tested, Zn-saturated EDTA failed to sustain the inhibitory effect, and added zinc ions restored the induction in the treated cells. Further, the antimycin A3-inducible mRNA level of the nuclear-encoded alternative oxidase gene detected by reverse transcriptase-PCR was significantly decreased by the treatment, and recovered to the level of untreated cells upon the addition of zinc ions. These results suggest that the treatment with pyrithione plus chelator resulted in an intracellular zinc-deficiency, which suppressed the expression of the nuclear-encoded alternative oxidase gene. The added zinc ions reversibly restored the expression, indicating that zinc is involved in the alternative oxidase gene expression.
