A chemical genomics approach toward understanding the global functions of the target of rapamycin protein (TOR)

The target of rapamycin protein (TOR) is a highly conserved ataxia telangie ctasia-related protein kinase essential for cell growth. Emerging evidence indicates that TOR signaling is highly complex and is involved in a variety of cellular processes. To understand its general functions, we took a chem ical genomics approach to explore the genetic interaction between TOR and o ther yeast genes on a genomic scale. In this study, the rapamycin sensitivi ty of individual deletion mutants generated by the Saccharomyces Genome Del etion Project was systematically measured. Our results provide a global vie w of the rapamycin-sensitive functions of TOR. In contrast to conventional genetic analysis, this approach offers a simple and thorough analysis of ge netic interaction on a genomic scale and measures genetic interaction at di fferent possible levels. It can be used to study the functions of other dru g targets and to identify novel protein components of a conserved core biol ogical process such as DNA damage checkpoint/repair that is interfered with by a cell-permeable chemical compound.