Sulfolobus

In taxonomy, Sulfolobus is a genus of the Sulfolobaceae.

Sulfolobus species grow in volcanic springs with optimal growth occurring at pH 2-3 and temperatures of 75-80 °C, making them acidophiles and thermophiles respectively. Sulfolobus cells are irregularly shaped and flagellar.

Sulfolobus species are generally named after the location from which they were first isolated, e.g. Sulfolobus Solfataricus was first isolated in the Solfatara (volcano). Other species can be found throughout the world in areas of volcanic or geothermal activity, such as geological formations called mud pots, which are also known as solfatara (plural of solfatare).

Sulfolobus as a model to study the molecular mechanisms of DNA replication
As the first Archaeal genome, Methanococcus jannaschii, has been sequenced completely, in 1996, it was found that the genes in the genome of Methanococcus jannaschii involved in DNA replication, transcription, translation, were more related to those counterparts in Eukaryote than in Bacteria. In 2001, the first genome sequence of Sulfolobus, Sulfolobus solfataricus P2, was published. In P2's genome, the genes related to chromosome replication were found to be more related to Eukaryote's. These genes include DNA polymerase, primase (including two subunits), MCM, CDC6/ORC1, RPA, RPC, PCNA. In 2004, the origins of DNA replication of Sulfolobus solfataricus and Sulfolobus acidocaldarius were identified. It showed that both species contained 3 origins in their genome. This is the first time that more than a single origin of DNA replication has been shown to be used in a prokaryotic cell. The mechanism of DNA replication in archaea is evolutionary conserved, and similar to that of Eukaryotes. Sulfolobus is now used as a model to study the molecular mechanisms of DNA replication in Archaea. And because the system of DNA replication in Archaea is much simpler than that in Eukarote, it was suggested that Archaea could be used as model to study the much more complexed DNA replication in Eukaryote.

Role in biotechnology
Sulfolobus proteins are of interest for biotechnology and industrial use due to their thermostable nature. Intracellular proteins are not necessarily stable at low pH however, as Sulfolobus species maintain a significant pH gradient across the outer membrane. Like all Crenarchaeota, they are metabolically dependent on sulfur: heterotrophic or autotrophic, their energy comes from the oxidation of sulfur and/or cellular respiration in which sulfur acts as the final electron acceptor. For example, S. tokodaii is known to oxidize hydrogen sulfide to sulfate intracellularly.

Sulfolobus as a viral host
Lysogenic viruses infect Sulfolobus for protection. The viruses cannot survive in the extremely acidic and hot conditions that Sulfolobus lives in, and so the viruses use Sulfolobus as protection against the harsh elements. This relationship allows the virus to replicate inside the archaea without being destroyed by the environment.

Genome status
The complete genomes have been sequenced for S. acidocaldarius DSM 639 (2,225,959 nucleotides), S. solfataricus P2 (2,992,245 nucleotides), and S. tokodaii str. 7 (2,694,756 nucleotides).

Scientific journals