Detoxification of benzaldehyde in Sulfolobus solfataricus is assisted by regulated expression of an alcohol dehydrogenase gene and a Mar-like operon

Archaea, are microorganisms adapted to live in extreme conditions particularly hostile for the life. Many external agents of biological, physical or chemical nature, can determine a further stress for the cell. To date, knowledge of response mechanisms to chemical stress in archaea is very scarce. The goal of this research work is the understanding of the molecular mechanisms that confer to the Crenarchaeon S. solfataricus the ability to survive in presence of aromatic aldehydes of phenolic origin. Once identified the partners involved in the response, it will be possible to set-up systems for the bio-monitoring and the bio-remediation of contaminated area. We recently discovered a putative detoxifying mechanism involving transcriptional regulation of Sso2536 gene, encoding for an alcohol dehydrogenase gene (adh), specific for the aromatic aldehydes. Investigation of cis acting sequences and transcriptional factors has allowed to identify at least three DNA binding proteins. In particular, one of these, named Bald16 (Sso1352), is expressed at higher levels when cells are grown in the presence of the toxic benzaldehyde. This protein has a bacterial homologue belonging to the Mar (Multiple Antibiotic Resistance) family of transcriptional regulators. It has been proposed that Bald16 could act as a transcriptional activator triggering adh expression to protect cells from an environmental stress due to phenolic-derived aldehydes by converting the aromatic aldehydes in the corresponding alcohol, less toxic for the cell.