Role of Mitochondrial Retrograde Pathway in Regulating Ethanol-Inducible Filamentous Growth in Yeast

Abstract

In yeast, ethanol is produced as a by-product of fermentation through glycolysis. Ethanol also stimulates a developmental foraging response called filamentous growth and is thought to act as a quorum-sensing molecule. Ethanol-inducible filamentous growth was examined in a small collection of wine/European strains, which validated ethanol as an inducer of filamentous growth. Wine strains also showed variability in their filamentation responses, which illustrates the striking phenotypic differences that can occur among individuals. Ethanol-inducible filamentous growth in Σ1278b strains was independent of several of the major filamentation regulatory pathways [including fMAPK, RAS-cAMP, Snf1, Rpd3(L), and Rim101] but required the mitochondrial retrograde (RTG) pathway, an inter-organellar signaling pathway that controls the nuclear response to defects in mitochondrial function. The RTG pathway regulated ethanol-dependent filamentous growth by maintaining flux through the TCA cycle. The ethanol-dependent invasive growth response required the polarisome and transcriptional induction of the cell adhesion molecule Flo11p. Our results validate established stimuli that trigger filamentous growth and show how stimuli can trigger highly specific responses among individuals. Our results also connect an inter-organellar pathway to a quorum sensing response in fungi.

Protective Role of Intracellular Melatonin Against Oxidative Stress and UV Radiation in Saccharomyces cerevisiae

“…Therefore, further insights into cell-to-cell communication and Mel membrane receptors are needed. In fact other molecules that derive from tryptophan metabolism, such as tryptophol and other aromatic alcohols, have been reported to act as quorum-sensing molecules ( Chen and Fink, 2006 ; González et al, 2017 ).…”

Aromatic Amino Acid-Derived Compounds Induce Morphological Changes and Modulate the Cell Growth of Wine Yeast Species

“…For the filamentous growth assay, two strains of each non- Saccharomyces species were tested, using the strain QA23 ( S. cerevisiae ) as a control ( González et al, 2017 ). Yeasts were grown on minimal medium [MM – 1x YNB w/o aa or ammonium, 2% (w/v) glucose, and 10 mM (NH 4 ) 2 SO 4 ] with agitation (120 rpm) for 16 h at 28°C before seeding on plates for filamentation analysis.…”

“…Yeasts were grown on minimal medium [MM – 1x YNB w/o aa or ammonium, 2% (w/v) glucose, and 10 mM (NH 4 ) 2 SO 4 ] with agitation (120 rpm) for 16 h at 28°C before seeding on plates for filamentation analysis. To evaluate invasive and pseudohyphal growth, three different media were used, with variations in glucose and nitrogen concentrations: SAD – synthetic medium [1x YNB w/o aa or ammonium, 2% (w/v) glucose, and 37 mM (NH 4 ) 2 SO 4 and 2% (w/v) agar], SALG – synthetic medium with low glucose [1x YNB w/o aa or ammonium, 0.5% (w/v) glucose, and 37 mM (NH 4 ) 2 SO 4 and 2% (w/v) agar] ( González et al, 2017 ), and SLAD – synthetic low-ammonium dextrose medium [SLAD – 1x YNB w/o aa or ammonium, 2% (w/v) glucose, and 50 μM (NH 4 ) 2 SO 4 and 2% (w/v) agar]. To test the effects of aromatic alcohols, the above media were supplemented with 500 μM of TyrOH (6,90 mg/L), TrpOH (8,06 mg/L) or PheOH (6,10 mg/L) or 2% (v/v) ethanol.…”

“…For example, the human pathogen Candida albicans ( Hornby et al, 2001 ; Chen et al, 2004 ; Biswas et al, 2007 ; Kruppa, 2009 ) undergoes pseudohyphal and hyphal growth (pathogenic form), which confers the ability to infect human tissues ( Lo et al, 1997 ; Leberer et al, 2001 ; Rocha et al, 2001 ). Filamentous growth in yeasts has been reported to occur in response to cell density and several molecules, such as aromatic alcohols and ethanol, have been identified as stimuli that induce these morphological changes ( Gimeno et al, 1992 ; Dickinson, 1996 ; Lorenz et al, 2000 ; González et al, 2017 ). Indeed, aromatic alcohols, tyrosol (TyrOH), tryptophol (TrpOH), and phenylethanol (PheOH), which are derived from the amino acids tyrosine, tryptophan, and phenylalanine, respectively, have been suggested to act as quorum sensing molecules (QSMs) in yeasts, regulating cell density and evoking morphogenetic transitions ( Chen et al, 2004 ; Chen and Fink, 2006 ).…”

“…The finding that different aromatic alcohols exert different responses on morphogenesis depending on the yeast species implicates these molecules as inducers of species-specific effects ( Chen and Fink, 2006 ). In a recent study, González et al (2017) showed that ethanol specifically induced filamentous growth under nitrogen-limiting conditions, whereas aromatic alcohols did not. Thus, environmental conditions impact the efficacy of these compounds.…”