Our group has participated in the European Union projects of Saccharomyces cerevisiae genome sequencing and functional analyses of newly identified genes.
In addition to the… from sequence to consequence/phenotype … systematic approaches, we are interested on the mechanisms governing gene expression regulated by DNA-binding transcription factors and chromatin regulators in response to particular environmental changes. Our reference system is the metalloregulated transcription modulated by metal availability in yeast.
S. cerevisiae is an excellent model eukaryotic organism, providing the power of genetics, a complete genome sequence with high-quality annotations, a variety of tools and procedures for genome/proteome-wide analyses and many genes and processes conserved even in mammals.
Copper and iron are nutrients essential for all organisms. They are important redox co-factors of many metabolic enzymes but they also catalyse cytotoxic reactions. Cells have developed mechanisms that tightly regulate the entrance of Fe/Cu in response to Fe/Cu ion concentration changes in the environment as well as cellular detoxification. Dissection of the components and mechanisms involved is crucial since a) many human genetic diseases (hematological, metabolic, neurodegenerative) are linked to aberrant Fe/Cu homeostasis b) for improvement of plant culturing and food quality and c) for environmental cleaning by microorganisms.
Metalloregulated transcription is a major aspect of metal homeostasis. In S. cerevisiae, the cellular sensors are specific DNA binding transcriptional regulators, the functionality of which is modulated directly by metals, by post-translational modifications and by specific protein interactions.
Our group has contributed by the identification of components of the (interconnected) Fe/Cu homeostasis pathways and analysis of their function. Additionally, we have identified by genetic and two-hybrid screens a number of specific novel protein interactions with the DNA binding transactivators Mac1p and Aft1p. We are currently analysing their biological significance by genetic, biochemical and molecular assays, including targeted gene deletions, genome localization by chromatin immunoprecipitation, genome-wide expression analyses, in vitro and in vivo protein interactions and multiprotein complex identification.
Novel protein interactions reveal through ‘guilt by association' new protein roles and facts concerning the mechanisms of chromatin organization and transcription per se, new protein modulators of the Fe/Cu-sensing transcription factors and new functional connections between transcription (or metalloregulated transcription) and other cellular signalling pathways (oxidative stress, DNA damage, etc). Recently published data from our group imply distinct novel interactions with known global regulators (Nhp6p, Ssn6p, Hir1p, Snf2p) affecting directly and specifically the functionality of Aft1p and/or Mac1p in addition to metal availability. They provide new insights and imply new pathway components that can be modulated quantitatively or qualitatively to ensure the all or none response of the cell to specific environmental stimuli.