GodS, a transcriptional regulator that responds to gold

MARIA EUGENIA PÉREZ AUDERO; PABLO BOTTA; MARTÍN ESPARIZ ; LUCAS B. PONTEL; SUSANA CHECA; FERNANDO SONCINI

Iguazú, Argentina

Congreso; Argentine Society for Biochemistry and Molecular Biology XL Annual Meeting. Protein Phosphorylation and; 2004

SAIB

The MerR family is a group of transcriptional regulators that respond specifically to a variety of environmental stimuli, such as oxidative stress, heavy metals or antibiotics. We have identified a gene, godS, coding for a MerR-like protein located in a Salmonella specific region. godS forms an operon with godT that encodes a metal transporter and is located upstream of godB, whose product has homology to copper chaperones.We demonstrated by b-galactosidase activity and western blot assays that GodS regulates not only the expression of godT and godB but also its own synthesis. The autoinduction reported here was not previously observed in other MerR like regulators from gram negative bacteria. Transcriptional activity analysis in the presence of mono, di or trivalent metal ions showed that this regulon is exclusively induced by gold salts. Moreover, this induction is abrogated by the deletion of godS, and fully restored upon expression of the regulator from a plasmid. We observed that GodS specifically binds to the promoter regions of godTS and godB in vitro even in the absence of gold. However, the presence of AuCl4H in the culture medium increased the level of GodS associated to these promoters. To our knowledge, this is the first evidence of transcriptional autoregulation for this kind of metalloregulatory proteins.