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Eukaryotic Cell, April 2009, p. 540-549, Vol. 8, No. 4
1535-9778/09/$08.00+0 doi:10.1128/EC.00007-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan,1 CREST, Japan Science and Technology Agency, 5, Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan2
Received 5 January 2009/ Accepted 10 February 2009
The glutathione redox system, including the glutathione biosynthesis and glutathione regeneration reaction, has been found to play a critical role in the yeast Pichia pastoris during growth on methanol, and this regulation was at least partly executed by the transcription factor PpYap1. During adaptation to methanol medium, PpYap1 transiently localized to the nucleus and activated the expression of the glutathione redox system and upregulated glutathione reductase 1 (Glr1). Glr1 activates the regeneration of the reduced form of glutathione (GSH). Depletion of Glr1 caused a severe growth defect on methanol and hypersensitivity to formaldehyde (HCHO), which could be complemented by addition of GSH to the medium. Disruption of the genes for the HCHO-oxidizing enzymes PpFld1 and PpFgh1 caused a comparable phenotype, but disruption of the downstream gene PpFDH1 did not, demonstrating the importance of maintaining intracellular GSH levels. Absence of the peroxisomal glutathione peroxidase Pmp20 also triggered nuclear localization of PpYap1, and although cells were not sensitive to HCHO, growth on methanol was again severely impaired due to oxidative stress. Thus, the PpYap1-regulated glutathione redox system has two important roles, i.e., HCHO metabolism and detoxification of reactive oxygen species.
Published ahead of print on 27 February 2009.
Supplemental material for this article may be found at http://ec.asm.org/.
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