Whi2 enhances methylmercury toxicity in yeast via inhibition of Akr1 palmitoyltransferase activity

Publication date: June 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 6
Author(s): Gi-Wook Hwang, Toru Fukumitsu, Yousuke Ogiwara, Tsutomu Takahashi, Nobuhiko Miura, Shusuke Kuge, Akira Naganuma
BackgroundWe have previously reported that Whi2 enhances the toxicity of methylmercury in yeast. In the present study we examined the proteins known to interact with Whi2 to find those that influence the toxicity of methylmercury.MethodsGene disruption and site-directed mutagenesis were employed to examine the relationship of mercury toxicity and palmitoylation. Protein palmitoylation was examined using the acyl-biotinyl exchange method. Protein–protein interactions were detected by immunoprecipitation and immunoblotting.ResultsWe found that deletion of Akr1, a palmitoyltransferase, rendered yeast cells highly sensitive to methylmercury, and Akr1 is necessary for the methylmercury resistance of Whi2-deleted yeast. Palmitoyltransferase activity of Akr1 has an important role in the alleviation of methylmercury toxicity. Whi2 deletion or methylmercury treatment enhanced the palmitoyltransferase activity of Akr1, and methylmercury treatment reduced the binding between Akr1 and Whi2.ConclusionsWhi2 bonds to Akr1 (a protein that is able to alleviate methylmercury toxicity) and thus inhibits Akr1's palmitoyltransferase activity, which leads to enhanced methylmercury toxicity. In contrast, methylmercury might break the bond between Whi2 and Akr1, which enhances the palmitoyltransferase activity of Akr1 to alleviate methylmercury toxicity.General significanceThis study's findings propose that the Whi2/Akr1 system can be regarded as a defense mechanism that detects methylmercury incorporation of yeast cells and alleviates its toxicity.



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