Functional genomics of the thermo-acidophilic archaeon Sulfolobus solfataricus

Archaea and bacteria that optimally grow at temperatures above 60C and 80C are referred to as thermophiles and hyperthermophiles, respectively (Stetter, 1996). Since their discovery in the late 1960s (Brock and Freeze, 1969), attempts were made to reveal the secrets of the thermal resistance of these microorganisms, initially by physiological, biochemical and genetic analysis (Allers and Mevarech, 2005). In addition, the sequencing of the genomes of many thermophiles during the last decade has allowed for a series of genome-based research lines. Comparative genomics is the in silico analysis of genome data that aims to predict the metabolic potential of an organism, including the interconversions of metabolites and the regulation thereof (Ettema et al., 2005; Makarova and Koonin, 2003). Functional genomics is the experimental analysis at the level of RNA (transcriptomics), protein (proteomics), as well as metabolites (metabolomics). In general, such holistic studies aim at addressing the phenotypic response of an organism either to different cultivation conditions, or to genotypic variations. Here we review recent developments of functional genomics of thermophiles in general, and of the thermo-acidophilic archaeon Sulfolobus solfataricus in particular.