Chronic environmental exposure to aluminium has been linked to cancers and neurodegeneration. Through a previous genome wide deletion study, using the model organism Saccharomyces cerevisiae, we have demonstrated that deletion of the catalytic subunit (CKA2) of the renowned tetrameric protein kinase CK2 results in a tolerant phenotype to Al3+. These findings provided the basis for our proteomic investigations into the mechanisms of Al3+ toxicity and detoxification.
Five strains of S. cerevisiae including Al3+ sensitive BY4743, cka1Δ, ckb1Δ and ckb2Δ as well as Al3+ tolerant cka2Δ were treated in duplicate with 1.6 mM Al3+ in a time-course (0 to 16 hr). Reverse phase chromatography was used for creation of the spectral library which was generated with ProteinPilotTM 5.0 and searched against the yeast Uniprot 2016 database for protein identification. The spectral library was imported into PeakViewTM 2.1 and matched against SWATH-MS data for protein quantification. Statistical analysis of the differentially expressed proteins with a fold change cut-off of 1.5 was performed using Perseus 188.8.131.52.
A total of 3196 proteins (1% FDR) were identified in this study and 2283 proteins were successfully quantified via SWATH-MS. In the Al3+ sensitive strains, Al3+ was found to damage the cell wall and plasma membrane, disrupts processes such as nucleotide synthesis and repair, amino acid metabolism, ribosome biogenesis and the anti-oxidant response. The key findings of the protective role of cka2Δ against Al3+ include overexpression of proteins in sulfur metabolism, lysine biosynthesis, anti-oxidants and the heat shock response.
These novel findings provide in-depth understanding of Al3+ toxicity and its detoxification, and have implications in finding solutions to Al3+-related problems such as neurodegenerative diseases and cancers.
Keywords: Aluminium toxicity, Protein kinase CK2, Proteomics, S. cerevisiae