Schizosaccharomyces pombe: Difference between revisions

From MicrobeWiki, the student-edited microbiology resource
Line 18: Line 18:


==Genome structure==
==Genome structure==
''S. pombe'' was the sixth organism with a nucleus to have its genome sequenced. ''S. pombe'' has a small and compact genome. Its genome contains 13.8 million base pairs distributed among chromosomes I (5.7 Mb), II (4.6 Mb) and III (3.5 Mb) and 4,824 genes. It has the lowest number of protein-coding genes yet identified in a free-living eukaryotic cell (3). The 3 chromosomes are linear, but circular chromosome formation has been observed in fission yeast mutants. If the ''S. pombe'' lose the simple repeats at the very ends of the chromosomes as well as much of the subtelomeric TAS elements, it will fuse end to end to generate circular chromosomes (4). The three centromeres are 35, 65, and 110 kb long for chromosomes I, II, and III respectively. This leaves about 12.5 Mb of unique sequence (3).
A total of 4,730 introns is distributed among 43% of ''S. pombe'' genes, with 15 being the largest number of introns found within a single gene. Of genes that have two or more introns, 614 have two introns, 324 have three, 148 have four, 70 have five and 40 have six (3). Therefore, the number of genes having an extra intron decreases by about half, as intron number increases from two to six per gene (3). These observations may be relevant when we study mechanisms by which introns are generated and removed. The large number of introns in ''S. pombe'' provides opportunities for alternative splicing to generate protein variants, which could have regulatory roles as well as increasing the range of protein types present in the cell (3).
The usefulness of ''S. pombe'' for investigating the functions of genes related to human disease is assessed. Protein-coding genes of ''S. pombe'' were identified that generate products with similarities to proteins coded by 289 genes that are mutated, amplified, or deleted in human disease (3). A total of 172 ''S. pombe'' proteins have similarity with members of this data set of human disease proteins. The largest groups of human disease-related genes are those implicated in cancer. There are 23 such genes and they are involved in DNA damage and repair, checkpoint controls, and the cell cycle, all processes in maintaining genomic stability (3). The cell cycle and checkpoint background of ''S. pombe'' make it a good model organism for studying these particular cancer disease pathways. Other categories represented in ''S. pombe'' are those involved in metabolic (12 genes), neurological (13 genes), cardiac (1 gene) and renal (1 gene) disease (3).


==Cell structure and metabolism==
==Cell structure and metabolism==

Revision as of 02:44, 21 August 2007

A Microbial Biorealm page on the genus Schizosaccharomyces pombe

Classification

Higher order taxa

Superkingdom: Eukaryota, Kingdom: Fungi, Phylum: Ascomycota, Subphylum: Dikarya, Subphylum: Taphrinomycotina, Class: Schizosaccharomycetes, Order: Schizosaccharomycetales, Family: Schizosaccharomycetaceae, Genus: Schizosaccharomyces (6)

Species

Schizosaccharomyces pombe (6)

Also known as: Schizosaccharomyces malidevorans (6)

Description and significance

Genome structure

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology

S. pombe is found in alcoholic beverages, and therefore, it does not play a role in the environment. However, it is one of the yeasts that play an important role in the ecology of Kombucha fermentation (5). Kombucha is a traditional fermentation of sweetened tea, involving a symbiosis of yeast species and acetic acid bacteria. The study of yeast ecology in Kombucha fermentation reveals that S. pombe works with other yeast species such as B. bruxellensis, C. stellata, T. delbrueckii, and Z. bailii (5). S. pombe and other yeasts would ferment the sugar in the tea medium to ethanol, and then ethanol is oxidized by the acetic acid bacteria to produce acetic acid. S. pombe is suited to the Kombucha environment because of its ability to tolerate high-sugar foods (5). Isolates of S. pombe, T. delbrueckki and Z. bailii exhibit tolerance up to 60% glucose concentration and are commonly associated with alcoholic fermentation for wine and champagne production. As the fermentation progressed, species with low acid tolerance decreased in population (5). Species such as S. pombe, with moderate tolerance to acidic conditions, die off after day 10. In general, Kombucha fermentation is initiated by osmotolerant species of yeast, which are capable of growing in the presence of high concentrations of sugar. The process is then succeeded and ultimately dominated by acid-tolerant species (5).

Pathology

The yeast Schizosaccaromyces pombe is a harmless, rapidly growing eukaryote. Therefore, there are no pathologies associated with this particular organism (2).

Application to Biotechnology

As of now, S. pombe is not used in any applications to biotechnology but remains an important model used in researching cell division in molecular genetics and cell biology (1).

Current Research

Enter summaries of the most recent research here--at least three required

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Rachel Larsen

Retrieved from "https://microbewiki.kenyon.edu/index.php?title=Schizosaccharomyces_pombe&oldid=19990"