title: Why are essential genes essential? - The essentiality ofSaccharomycesgenes.
abstract: Essential genes are defined as required for the survival of an organism or a cell. They are of particular interests, not only for their essential biological functions, but also in practical applications, such as identifying effective drug targets to pathogenic bacteria and fungi. The budding yeastSaccharomyces cerevisiaehas approximately 6,000 open reading frames, 15 to 20% of which are deemed as essential. Some of the essential genes, however, appear to perform non-essential functions, such as aging and cell death, while many of the non-essential genes play critical roles in cell survival. In this paper, we reviewed and analyzed the levels of essentiality of theSaccharomyces cerevisiaegenes and have grouped the genes into four categories: (1) Conditional essential: essential only under certain circumstances or growth conditions; (2) Essential: required for survival under optimal growth conditions; (3) Redundant essential: synthetic lethal due to redundant pathways or gene duplication; and (4) Absolute essential: the minimal genes required for maintaining a cellular life under a stress-free environment. The essential and non-essential functions of the essential genes were further analyzed.
authors.affiliation: Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: Zhaojie
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: Qun
authors.initials: Q
authors.lastname: Ren
keywords: Saccharomyces cerevisiae; cell death; cell survival; essential genes; growth conditions