Lipid Hydroperoxides Activate the Mitogen-activated Protein Kinase Mpk1p in Saccharomyces cerevisiae

Abstract

Saccharomyces cerevisiae is capable of responding to oxidants, including lipid peroxidation products. We investigate here the role of the mitogen-activated protein kinase Mpk1p in protection against linoleic acid hydroperoxide (LoaOOH), a product of radical attack on an unsaturated lipid. MPK1 was found to be required for resistance to LoaOOH. Furthermore, Mpk1p was rapidly and transiently phosphorylated in response to LoaOOH. This phosphorylation was dose-dependent and stimulated by sublethal concentrations as low as 1 M in the external medium. Such low doses have been shown to result in resistance to subsequent challenge with a higher dose through the process of adaptation. However MPK1 was not essential for this adaptive response. MPK1 was also not involved in cell cycle modulation and acted independently of the cell cycle-regulating Oca1p. Transcriptional profiling of the mpk1⌬ cells during LoaOOH stress indicated that Mpk1p may be important in effecting changes to the cell surface and metabolism during LoaOOH exposure. Furthermore, it revealed that Mpk1p is required for the regulation of 97 LoaOOHresponsive transcripts. Evidence is presented that the activation of Mpk1p may be caused by the activation of protein kinase C by LoaOOH.

The SPI1 Gene, Encoding a Glycosylphosphatidylinositol-Anchored Cell Wall Protein, Plays a Prominent Role in the Development of Yeast Resistance to Lipophilic Weak-Acid Food Preservatives

“…In particular, the mechanisms underlying the involvement of the GPI-CWP Spi1p, examined in the present study, in yeast response to stress certainly deserve attention. In fact, the inspection of results from microarray analysis obtained in recent years reveals that SPI1 transcription, together with the transcription of other genes encoding proteins that have a structural role in cell architecture, is activated in response to a number of environmental stress conditions, including osmotic stress, lipid peroxidation, low external pH, stress induced by the herbicide 2,4-D, and heat stress (2,4,14,15,23,25,29). SPI1 is also up-regulated in response to cell wall-destabilizing conditions, involving cell wall mutations or the application of hydrolytic enzymes such as Zymolyase (13,19).…”

“…Global expression analysis carried out in recent years has indicated that yeast cells respond to environmental stress by modifying the organization of the cell wall (13,19). This cell remodeling may compensate for the damage produced in the cell wall, may increase protection against diverse stresses, and may result in the rapid induction of resistance to cell wall-lytic enzymes (2,4,8,13,14,15,23,25,28,29). Nevertheless, the specific role of cell wall-associated proteins in this stress response and their contribution to the development of stress resistance remain unclear.…”

Regulation of Cell Wall Biogenesis in Saccharomyces cerevisiae: The Cell Wall Integrity Signaling Pathway

“…Current understanding of each of the inputs and outputs of this pathway related to the maintenance of cell wall integrity will be discussed individually. Although the CWI pathway has additionally been implicated in the responses to oxidative stress (Alic et al 2003;Vilella et al 2005), high and low pH stress (Claret et al 2005;Serrano et al 2006), and DNA damage (Queralt and Igual 2005;Dardalhon et al 2009;Truman et al 2009;Bandyopadhyay et al 2010), this review article will be restricted to its role in the maintenance of cell wall integrity.…”

Effects of Fluconazole on the Secretome, the Wall Proteome, and Wall Integrity of the Clinical Fungus Candida albicans

“…For instance, stretching of the plasma membrane, hypo-osmotic shock, exposure to the wall-degrading enzyme preparation Zymolyase or to wall-perturbing compounds such as calcofluor white, which binds chitin, and Congo red, which preferentially perturbs wall construction in the neck region (29), lead to activation of the CWI pathway (17,26,42,47). Another trigger is oxidative stress (4,47). Upon alterations in the fungal wall, plasma membrane-bound sensor proteins get activated and trigger mitogen-activated protein kinase (MAPK) signaling cascades that end in the activation of tran-scription factors involved in wall maintenance.…”