Developing a Novel and Optimized Yeast Model for Human VDAC Research

The voltage-dependent anion-selective channel (VDAC) plays a crucial role in mitochondrial function, and VDAC paralogs are considered to ensure the differential integration of mitochondrial functions with cellular activities. Heterologous expression of VDAC paralogs in the yeast Saccharomyces cerevisiae por1Δ mutant cells is often employed in studies of functional differentiation of human VDAC paralogs (hVDAC1-hVDAC3) regardless of the presence of the yeast second VDAC paralog (yVDAC2) encoded by the POR2 gene. Here, we applied por1Δpor2Δ double mutants and relevant por1Δ and por2Δ single mutants, derived from two S. cerevisiae strains (M3 and BY4741) differing distinctly in auxotrophic markers but commonly used for heterologous expression of hVDAC paralogs, to study the effect of the presence of yVDAC2 and cell genotypes including MET15, the latter resulting in a low level of hydrogen sulfide (H₂S), on the complementation potential of heterologous expression of hVDAC paralogs. The results indicated that yVDAC2 might contribute to the complementation potential. Moreover, the possibility to reverse the growth phenotype through heterologous expression of hVDAC paralogs in the presence of the applied yeast cell genotype backgrounds was particularly diverse for hVDAC3 and depended on the presence of the protein cysteine residues and expression of MET15. Thus, the difference in the set of auxotrophic markers in yeast cells, including MET15 contributing to the H₂S level, may create a different background for the modification of cysteine residues in hVDAC3 and thus explain the different effects of the presence and deletion of cysteine residues in hVDAC3 in M3-Δpor1Δpor2 and BY4741-Δpor1Δpor2 cells. The different phenotypes displayed by BY4741-Δpor1Δpor2 and M3-Δpor1Δpor2 cells following heterologous expression of a particular hVDAC paralog make them valuable models for the study of human VDAC proteins, especially hVDAC3, as a representative of VDAC protein sensitive to the reduction-oxidation state.