A cool tool for hot and sour Archaea: Proteomics of S ulfolobus solfataricus

In recent years, much progress has been made in proteomic studies to unravel metabolic pathways and basic cellular processes. This is especially interesting for members of the Archaea, the third domain of life. Archaea exhibit extraordinary features and many of their cultivable representatives are adaptable to extreme environments. Archaea harbor many unique traits besides bacterial attributes, such as size, shape, and DNA structure and eukaryal characteristics like information processing. Sulfolobus solfataricus P2, a thermoacidophilic archaeal representative, is a well-established model organism adapted to low-pH environments (pH 2-3) and high temperatures (80°C). The genome has a size of 3 Mbp and its sequence has been deciphered. Approximately 3033 predicted open reading frames have been identified and the genome is characterized by a great number of diverse insertion sequence elements. In unraveling the organisms' metabolism and lifestyle, proteomic analyses have played a major role. Much effort has been directed at this organism and is reviewed here. With the help of proteomics, unique metabolic pathways were resolved in S. solfataricus, targets for regulatory protein phosphorylation identified, and cellular responses upon virus infection as well as oxidative stress analyzed.