Aggregation selection · Genome-wide screen of aggregation selection

Genome-wide screen of aggregation selection

In order to carry out their biological function, proteins must fold into a unique native state. However, the failure of a polypeptide to acquire or maintain this native state can result in protein aggregation, caused by the interaction of solvent-exposed hydrophobic stretches. The study of this event has grown into a dynamic scientific field, mainly due to its association with numerous human diseases such as Alzheimer’s and Parkinson’s disease. Moreover, aggregation is one of the most critical problems in recombinant protein expression in experimental investigations and large-scale protein production. In contrast, in addition to playing a role in pathogenicity, numerous examples exist of cells exploiting protein aggregation for crucial functional purposes, such as scaffolding melanin in the skin or storing hormones intracellularly. To investigate the molecular events underlying the intracellular aggregation process and aggregation-driven toxicity, several model systems have been developed. Simple unicellular organisms, such as bacteria or yeast, are used as models for studying protein deposition inside the cell, as they have simple growth requirements and an extensive background knowledge base (e.g. well annotated genomes sequences). Genome-wide screens in these organisms identified processes that maintain proteome stability and promote folding and clearance (e.g. chaperones, proteasome subunits, stress- induced transcriptional regulators). The project that I am presenting aspires to quantitatively identify modifiers of the protein aggregation effect on cell fitness by employing a genetic screening strategy in S. cerevisiae (Figure 1). Additionally, our model can distinguish and quantify how much the fitness effect is governed through foci formation, or specific loss- and gain-of-function. An understanding of these determinants is essential in order to i) unravel how the cell regulates the aggregation process; ii) develop new strategies for tackling the debilitating pathologies associated with protein aggregation; and to iii) increase the solubility and functionality of recombinant proteins. **Conclusion** - We identified a number of genes that are able to modulate the aggregation process and are significantly different dependent on whether the aggregated protein is essential, non-essential or toxic. - The methodology of the screen has been validated as some of the genes or a similar functional class has been reported in previous studies. - Using a systems-biolog approach, we could not identify a significant difference in either a) ontology or b) pathway enrichment in the different conditions tested.

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