YPK9 and WHI2 Negatively Interact during Oxidative Stress.

Florenal Joseph,William J Chirico,Oleg V Evgrafov,Darach Miller

doi:10.3390/microorganisms9122584

Abstract

Yeast PARK9 (YPK9) shares homology with human ATP13A2, which encodes a polyamine transporter implicated in juvenile forms of Parkinson’s disease. We used YPK9 to gain insight into how ATP13A2 affects cell growth and sensitivity to oxidative stress. Surprisingly, the YPK9 deletion strain from the Saccharomyces cerevisiae deletion collection (YKO) in wildtype BY4741 (mating type a) grew faster and was more resistant to hydrogen peroxide than a commercial, putative parental BY4741 wildtype strain (BY4741COM). In contrast, deleting YPK9 from BY4741COM rendered it very sensitive to hydrogen peroxide, suggesting its background is different from that of the deletion collection. Whole-genome sequencing revealed that BY4741COM and BY4741COM ypk9∆ contain a novel premature stop codon near the 3′ end of WHI2 (WHI2G1324T), whereas the collection’s YPK9 deletion strain contains WHI2, which encodes a 486 amino acid protein, Whi2p. Replacing full-length WHI2 with the sequence coding for the predicted truncation (Whi2pE442*) rendered strains more sensitive to hydrogen peroxide, whereas the converse replacement rendered them more resistant. The sequences of WHI2 in 20 randomly chosen strains from the collection encode the full-length protein, indicating that the putative parental BY4741 WHI2G1324T strain’s genetic background differs from that of the deletion collection. Examination of WHI2 sequences in several commonly used wildtype S. cerevisiae strains and isolates revealed other Whi2p truncations that might yield altered phenotypes. Together, these results demonstrate a novel premature stop codon in WHI2 that renders yeast sensitive to hydrogen peroxide; they also reveal a negative genetic interaction between WHI2 and YPK9 in the presence of hydrogen peroxide in the BY4741 background.

Highlights

Lindquist et al first identified Yeast PARK9 (YPK9) as a suppressor of α-synuclein toxicity in yeast [1].α-synuclein is the major component of Lewy bodies, which are cytoplasmic structures that are the hallmark of Parkinson’s disease
Based on YPK9’s sequence homology to human ATP13A2, we speculated that a strain lacking YPK9 would have a growth defect and be sensitive to oxidative stress
At least two explanations are possible for the difference in hydrogen peroxide sensitivity of the two ypk9∆ strains

Summary

Introduction

Lindquist et al first identified YPK9 as a suppressor of α-synuclein toxicity in yeast [1]. Α-synuclein is the major component of Lewy bodies, which are cytoplasmic structures that are the hallmark of Parkinson’s disease. S. cerevisiae YPK9 is 38% identical to human. ATP13A2 [2], which encodes a multispanning membrane protein of lysosomes that exports polyamines to the cytosol [3]. Mutations in human ATP13A2 are associated with. Kufor–Rakeb syndrome, an early onset form of Parkinson’s disease [4]. The convergence of oxidative stress, protein condensates, and polyamine metabolism on YPK9 may yield insight into the dysregulation of fundamental pathways underlying Parkinson’s disease. WHI2 was originally identified by Sudbery et al [7] during a screen for cell-cycle mutants. The whi mutant yielded small, mostly budding cells in the stationary phase

Methods

Results

Conclusion