Identification of novel peroxisome functions in yeast

Singh, R. (2019). Identification of novel peroxisome functions in yeast. [Groningen]: University of Groningen.

Peroxisomes are ubiquitous cell organelles that play a central role in cellular lipid metabolism. Peroxisomes also possess enzymes to maintain redox balance and counteract oxidative stress. Recent studies resulted in the identification of several novel and often unexpected peroxisome functions, including non-metabolic roles. These novel functions are often related to stress and stress adaptations. The present study aims to extend the atlas of peroxisome functions by the identification of novel stress-related, yeast peroxisomal proteins. Through mass spectrometry analysis of peroxisomal fractions isolated from Hansenula polymorpha cells exposed to ethanol stress, we identified six putative peroxisomal peroxiredoxins. Two of them, named C8BNF3 and C8BNF4, contain a putative peroxisomal targeting signal 1. Peroxiredoxins are ubiquitous thiol-specific proteins that have multiple functions in stress protection, including defense against oxidative stress. The localization analysis using fusion proteins with green fluorescent protein and fluorescence microscopy indicated that C8BNF3 is a mitochondrial potein, whereas C8BNF4 partially localizes to peroxisomes in glucose- grown cells. The c8bnf4 mutant displays no growth defect and shows no enhanced sensitivity to any of the stress conditions tested. Taken together, we have identified a novel peroxisomal peroxiredoxin in H. polymorpha, whose function remains to be established.