PgmNr Y3116: Magnification of negative allelic effects by environmental stress renders yeast segregants unable to grow at 37°C on ethanol.

Authors:
T. Matsui; I. Ehrenreich


Institutes
U. of Southern California, Los Angeles, CA.


Keyword: Transcription

Abstract:

The budding yeast Saccharomyces cerevisiae is a valuable model system for characterizing the genetic and molecular mechanisms that enable fungal growth at human body temperature (37°C). However, most work on this topic has been performed on glucose, the organism’s preferred carbon source. In contrast, much less is known about the mechanisms that enable growth at 37°C on non-preferred carbon sources, such as ethanol. To provide new insights into this problem, we comprehensively dissected the genetic basis of inability to grow at 37°C on ethanol (37e) in a cross of the BY4716 (BY) lab strain and the YJM789 (YJM) clinical isolate. In total, we detected 15 loci, with roughly half of the causal alleles contributed by each cross parent. We then cloned and measured the quantitative growth effects of four loci that, in an otherwise YJM genetic background, result in a broad spectrum of growth levels at 37e. Based on this work, we resolved three of these loci to a kinase (IKS1), a component of the vacuolar protein sorting machinery (VPS70), and a stress granule-associated RNA binding protein (YGR250C). We found that these loci mainly contribute to inability to grow at 37e through large additive effects. However, the effects of these four loci are not specific to 37e, as each locus also shows a significant, but appreciably weaker growth effect on ethanol at standard culturing temperature (30°C) and on glucose at 37°C. This latter finding suggests that inability to grow at 37e is caused by additive genetic variants that show effects that are intensified in a more stressful environment.



Yeast Database Genetic Index
1. systematic name: YGR250C
2. systematic name: YJL057C
3. systematic name: YJR126C