Sulfolobus islandicus
Classification
Higher Order Taxa
Domain(Archaea); Phylum(Crenarchaeota); Class(Thermoprotei); Order(Sulfolobales); Family (Sulfolobacae);
Genus species
Sulfolobus islandicus
Description and Significance
‘Island’ is German for Iceland where many hyperthermophilic crenarchaea and many Sulfolobales strains have been found (5).
9 S. islandicus strains are known and sequenced and are found to live among volcano springs and other hot areas with temperatures of 59-91 °Celsius (7). However, following the link to [DOE-JGI Integrated Microbial Genomes] will show you 130 different strains and a phylogenetic tree to show how they are related to one another. The species is coccus-shaped and is stained as gram negative. The cells of the L.D.8.5 strain are aerobes and like an environment with the pH around 2.7 (2).
The seven strains that were sequenced at the time of the study called, “Biogeography of the Sulfolobus islandicus pan-genome,” were found to have a core genome, which was common in all, and a variable portion which contained horizontally transferred genes or ones that were lost through evolution and separation among the species. The variable genes were put through the BLAST technology and were found to have close matches with closely related Sulfolobales species and their mobile elements. The study found that the two North American strains were more similar to each other than to the Mutnovsky population in Russia (7).
Genome Structure
The Sulfolobus islandicus has one circular chromosome. The strain L.D.8.5 taken from Devil’s Kitchen at Lassen National Park in California has 2,748,647 bp with a G-C content of 35.26% with 1 plasmid and five [CRISPR](Clustered regularly interspaced short palindromic repeat) sequences. 98.4% of the genes code for proteins (2). The plasmid pRN1 from the strain REN1H1 is 5350 base pairs with 37.27% G-C content and contains six genes which all code for proteins of which one is horizontally transferred (3).
The genome was found to have three replication origins. The genes closer to the origins O2 and O3 were found to be more abundantly expressed, conserved and more slowly evolved, whereas the more variable genes were found to be expressed later in replication. To learn more about these origins, take a look at the study Evolutionary Rates and Gene Dispensability Associate with Replication Timing in Archaeon Sulfolobus islandicus (4). Multiple replication origins is also found in Sulfolobus solfataricus and Sulfolobus acidocaldarius. Another species called Aeropyrum pernix, which is actually distantly related to the Sulfolobus, has been found to have two origins (8). How this evolutionary difference in origin number came to the species is unknown at this time.
The strains REY15A and HVE10/4 have 45 tRNA genes and 2-3 pseudo-tRNA genes located in the conserved region of their genomes with introns approximately 12-65 bp in length immediately 3’ to the anticodon and are supposed to be a protection against integration into these genes. Miniature inverted-repeat transposable elements (MITEs) are found downstream from tRNA genes but because of the likelihood of numerous integrations, the origins of these conserved sequences are difficult to determine. However, looking at Table 2 of the report entitled, Genome Analyses of Icelandic Strains of Sulfolobus Islandicus, Model Organisms for Genetic and Virus-Host Interaction Studies shows mostly the origin of integrated genes came from conjugative plasmids; however integration is shown at tRNAThr[GGT] by a spindle-shaped fusellovirus (5).
Cell Structure
The coccus shaped Sulfolobus islandicus is found to be Gram negative and to be arranged in single cells or considered to be free living (2). This topic has little information to be found and even pictures of this Archaea are scarce except for the Sulfolobus islandicus rod-shaped virus which is separate from this microbe.
Metabolism
The Archaea of the Sulfolobus genus are lithoautotrophic, oxidizing sulfur or lithotrophic, using sulfur to oxidize reduced carbon compounds. The strain of Sulfolobus islandicus L.D.8.5 are auxotrophs; due to a mutation these cells cannot produce several amino acids through biosynthesis and must take them up from the environment. However, they are prototrophic with respect to L-glutamate because they can biosynthesize this amino acid along with L-aspartate, L-tryptophan, L-asparagine, and several others . This strain specifically reduces sulfur in its metabolic pathways (2).
Ecology
Sulfolobus islandicus are found to live among volcano springs and other hot areas with temperatures of 59-91 °Celsius (7).
There appears to be biogeographical differentiation due to host cells and mobile elements. The Sulfolobus islandicus strains found in Mutnovsky Volcano Region were discovered to have a new form of microbial resistance through a rapidly evolving, sequence specific immunity mechanism that is triggered when viral DNA is introduced to the chromosome. The CRISPR gene is activated and a new spacer sequence is added to the leader end of CRISPR loci in response to a mobile element invasion from a virus or other competition (6).
Pathology
No known pathology
References
1) Berkner, Silvia and Lipps, Georg. (2007). An Active Nonautonomous Mobile Element in Sulfolobus islandicus REN1H1. Journal of Bacteriology. 189:5; 2145-49; doi: 10.1128/JB.01567-06.
2) DOE Joint Genome Institute. http://img.jgi.doe.gov/cgi-bin/w/main.cgi?section=TaxonDetail&taxon_oid=646311959. Accessed on 4/4/12.
3) DOE Joint Genome Institute. http://img.jgi.doe.gov/cgi-bin/w/main.cgi?section=TaxonDetail&taxon_oid=640048575. Accessed on 4/4/12.
4) Flynn, Kenneth M.; Vohr, Samuel H.; Hatcher, Philip J. and Cooper, Vaughn S. (2010). Evolutionary Rates and Gene Dispensability Associate with Replication Timing in the Archaeon Sulfolobus islandicus. Genome Biology and Evolution Oxford Journal, 2, 859-869; doi: 10.1093/gbe/evq068
5) Guo, Li; Brügger, Kim; Liu, Chao; Shah, Shiraz A.; Zheng, Huajun; Zhu, Yongqiang; Wang, Shengyue; Lillestøl, Reidun K.; Chen, Lanming; Frank, Jeremy; Prangishvili, David; Paulin, Lars; She, Qunxin; Huang, Li; and Garrett, Roger A. (2011). Genome Analyses of Icelandic Strains of Sulfolobus islandicus, Model Organisms for Genetic and Virus-Host Interaction Studies. Journal of Bacteriology. 193:7, 1672-1680; doi: 10.1128/JB.01487-10
6) Held, Nicole L., Herrera, Alfa, Cadillo-Quiroz, Hinsby, and Whitaker, Rachel J. (2010) CRISPR Associated diversity within a population of Sulfolobus islandicus. PLoS ONE 5:9, e12988 doi: 10.1371/journal.pone.0012988.
7) Reno ML, Held NL, Fields CJ, Burke PV, Whitaker RJ. (2009) Biogeography of Sulfolobus islandicus pan-genome, PNAS 106:21, 8605-10; doi: 10.1073/pnas.0808945106
8) Robinson, Nicholas P. and Bell, Stephen D. (2007) Extrachromosomal element capture and the evolution of multiple replication origins in archaeal chromosomes. PNAS 104:14, 5806-5811; doi: 10.1073/pnas.0700206104
Page authored by Candace M. Arno, student of Prof. Dr. Lisa Moore at The University of Southern Maine.
