Probing metazoan apoptotic regulators using yeast

Our group characterises cell death pathways, and their dysregulation in cancer and following viral infection. Some projects involve identification and characterisation of apoptosis pathway components, and definition of their mechanisms of action. In addition to standard protein biochemistry and cell biology techniques, these projects also exploit a suite of yeast-based systems we developed for identifying and characterising proteins and drugs that modulate apoptotic signalling. Active forms of the major apoptotic effectors – caspases, Bax and Bak – are all lethal to the budding yeast Saccharomyces cerevisiae.

We have exploited this lethality to reconstitute mammalian, insect and nematode apoptotic pathways in yeast. These reconstituted pathways have allowed us to investigate the specificity and activity of endogenous and viral proteins regulate apoptosis, and we have identified apoptotic inhibitors using functional yeast-based screens.

We have also recently adapted this system to define the specificity of drugs that modulate apoptotic signalling by antagonising Bcl-2 relatives or caspases. Using a second yeast-based system, caspase activity can be monitored in yeast via cleavage-dependent liberation of a transcription factor from the plasma membrane, enabling it to activate the lacZ reporter gene. We have employed this system to define the specificity of mammalian and nematode caspases.