Sulfolobus
Encyclopedia
Sulfolobus is a genus
of microorganism
in the family Sulfolobaceae
. It belongs to the archea domain.
Sulfolobus species grow in volcanic spring
s with optimal growth occurring at pH
2-3 and temperature
s of 75-80 °C, making them acidophile
s and thermophiles respectively. Sulfolobus cells are irregularly shaped and flagellar.
Species of Sulfolobus 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 solfatare (plural of solfatara).
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 Eukaryotes than in prokaryotes. 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 eukaryotes. 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 2 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.
s. Intracellular proteins are not necessarily stable at low pH however, as Sulfolobus species maintain a significant pH gradient across the outer membrane. Sulfolobales are metabolically dependent on sulfur: heterotroph
ic or autotroph
ic, 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.
s 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).
All Archaea have lipids with ether links between the head group and side chains, making the lipids more resistant to heat and acidity than bacterial and eukaryotic ether-linked lipids. The Sulfolobales are known for unusual tetraether lipids.In Sulfolobales, the ether-linked lipids are joined covalently across the "bilayer," making tetraethers. Technically, therefore, the tetraethers form a monolayer, not a bilayer. The tetraethers help Sulfolobus species survive extreme acid as well as high temperature.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
in the family Sulfolobaceae
Sulfolobaceae
In taxonomy, the Sulfolobaceae are a family of the Sulfolobales.-External links:...
. It belongs to the archea domain.
Sulfolobus species grow in volcanic spring
Hot spring
A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.-Definitions:...
s with optimal growth occurring at pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
2-3 and temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
s of 75-80 °C, making them acidophile
Acidophile
Acidophile may refer to:* Acidophile * Acidophile...
s and thermophiles respectively. Sulfolobus cells are irregularly shaped and flagellar.
Species of Sulfolobus are generally named after the location from which they were first isolated, e.g. Sulfolobus solfataricus was first isolated in the Solfatara (volcano)
Solfatara (volcano)
Solfatara is a shallow volcanic crater at Pozzuoli, near Naples, part of the Campi Flegrei volcanic area. It is a dormant volcano, which still emits jets of steam with sulphurous fumes. The name comes from the Latin, Sulpha terra, "land of sulphur", or "sulfur earth"...
. 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 solfatare (plural of solfatara).
Sulfolobus as a model to study the molecular mechanisms of DNA replication
As the first Archaeal genome, MethanococcusMethanococci
In taxonomy, the Methanococci are a class of the Euryarchaeota.-External links:...
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 Eukaryotes than in prokaryotes. 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 eukaryotes. These genes include DNA polymerase, primase (including two subunits), MCM, CDC6/ORC1, RPA, RPC, PCNA
PCNA
Proliferating Cell Nuclear Antigen, commonly known as PCNA, is a protein that acts as a processivity factor for DNA polymerase δ in eukaryotic cells. It achieves this processivity by encircling the DNA, thus creating a topological link to the genome...
. In 2004, the origins of DNA replication of Sulfolobus solfataricus and Sulfolobus acidocaldarius were identified. It showed that both species contained 2 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. One application is the creation of artificial derivatives from S. acidocaldarius proteins, named affitinAffitin
Affitins are artificial proteins with the ability to selectively bind antigens. They are structurally derived from the DNA binding protein Sac7d, found in Sulfolobus acidocaldarius, a microorganism belonging to the archaea domain...
s. Intracellular proteins are not necessarily stable at low pH however, as Sulfolobus species maintain a significant pH gradient across the outer membrane. Sulfolobales are metabolically dependent on sulfur: heterotroph
Heterotroph
A heterotroph is an organism that cannot fix carbon and uses organic carbon for growth. This contrasts with autotrophs, such as plants and algae, which can use energy from sunlight or inorganic compounds to produce organic compounds such as carbohydrates, fats, and proteins from inorganic carbon...
ic or autotroph
Autotroph
An autotroph, or producer, is an organism that produces complex organic compounds from simple inorganic molecules using energy from light or inorganic chemical reactions . They are the producers in a food chain, such as plants on land or algae in water...
ic, their energy comes from the oxidation of sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
and/or cellular respiration
Cellular respiration
Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate , and then release waste products. The reactions involved in respiration are catabolic reactions that involve...
in which sulfur acts as the final electron acceptor. For example, S. tokodaii is known to oxidize hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
to sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
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 genomeGenome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
s 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).
Genome structure
The archaeon Sulfolobus solfataricus has a circular chromosome that consists of 2,992,245 bp. Another sequenced species, S. tokodaii has a circular chromosome as well but is slightly smaller with 2,694,756 bp. Both species lack the genes ftsZ and minD, which has been characteristic of sequenced crenarchaeota. They also code for citrate synthase and two subunits of 2-oxoacid:ferredoxin oxidoreductase, which plays the same role as alpha-ketoglutarate dehydrogenase in the TCA cycle. This indicates that Sulfolobus has a TCA cycle system similar to that found in mitochondria of eukaryotes. Other genes in the respiratory chain which partake in the production of ATP were not similar to what is found in eukaryotes. Cytochrome c is one such example that plays an important role in electron transfer to oxygen in eukaryotes. This was also found in A. pernix K1. Since this step is important for an aerobic microorganism like Sulfolobus, it probably uses a different molecule for the same function or has a different pathway.Cell structure and metabolism
Sulfolobus can grow either lithoautotrophically by oxidizing sulfur, or chemoheterotrophically using sulfur to oxidize simple reduced carbon compounds. Heterotrophic growth has only been observed, however, in the presence of oxygen. The principle metabolic pathways are a glycolytic pathway, a pentose phosphate pathway, and the TCA cycle.All Archaea have lipids with ether links between the head group and side chains, making the lipids more resistant to heat and acidity than bacterial and eukaryotic ether-linked lipids. The Sulfolobales are known for unusual tetraether lipids.In Sulfolobales, the ether-linked lipids are joined covalently across the "bilayer," making tetraethers. Technically, therefore, the tetraethers form a monolayer, not a bilayer. The tetraethers help Sulfolobus species survive extreme acid as well as high temperature.
Ecology
S. solfataricus has been found in different areas including Yellowstone National Park, Mount St. Helens, Iceland, Italy, and Russia to name a few. Sulfolobus is located almost wherever there is volcanic activity. They thrive in environments where the temperature is about 80oC with a pH at about 3 and sulfur present. Another species, S. tokodaii, has been located in an acidic spa in Beppu Hot Springs, Kyushu, Japan. Sediments from ~90m below the seafloor on the Peruvian continental margin are dominated by intact archaeal tetraethers, and a significant fraction of the community is sedimentary archaea taxonomically linked to the crenarchaeal Sulfolobales (Sturt, et al, 2004).Phages
The Sulfolobus viruses are temperate or permanent lysogens. Permanent lysogens differ from lysogenic bacterial phages in that the host cells are not lysed after the induction of Fuselloviridae production and eventually return to the lysogenic state. They are also unique in the sense that the genes encoding the structural proteins of the virus are constantly transcribed and DNA replication appears to be induced. The viruses infecting archaea like Sulfolobus have to use a strategy to escape prolonged direct exposure to the type of environment their host lives in, which may explain some of their unique properties.External links
- Comparative Analysis of Sulfolobus Genomes (at DOE'sUnited States Department of EnergyThe United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
IMG systemIntegrated Microbial Genomes SystemThe Integrated Microbial Genomes is a genome browsing and annotation system developed by the DOE-Joint Genome Institute. IMG contains all the draft and complete microbial genomes sequenced by the DOE-JGI integrated with other publicly available genomes...
) - Sulfolobus Genome Projects (from Genomes OnLine Database)