Zinc ions inhibit the protein-DNA complex formation between cyanobacterial transcription factor SmtB and its recognition DNA sequences
2002
Morita, E.H. | Wakamatsu, M. | Uegaki, K. | Yumoto, N. | Kyogoku, Y. | Hayashi, H.
SmtB is a trans-acting dimeric repressor of the metal-regulated smtA gene, and the release of SmtB from the smtA operator/promoter region is essential for the tolerance to Zn2+ stress by SmtA expression. Gel retardation assaying demonstrated that different sizes of SmtB-DNA complexes were formed depending on the DNA sequences, and the amounts of these complexes decreased in the presence of Zn2+. Here, we present the first direct evidence that Zn2+ (>4 miceomolar) inhibits the SmtB-DNA complex formation in vitro, which ensures the physiological functions of SmtB as a Zn2+ sensor and a transcription factor.
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