Streptomyces avermitilis: Difference between revisions

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(2) [http://www.springerlink.com/content/7jtmb74kpepq0gd4/fulltext.pdf Demain, A. "Pharmaceutically active secondary metabolites of microorganisms." ''Appl. Microbiol. Biotechnol.'' 1999. Vol 52, p. 455-463.]
(2) [http://www.springerlink.com/content/7jtmb74kpepq0gd4/fulltext.pdf Demain, A. "Pharmaceutically active secondary metabolites of microorganisms." ''Appl. Microbiol. Biotechnol.'' 1999. Vol 52, p. 455-463.]
(3) [http://www.pnas.org/cgi/reprint/211433198v1 Omura, S., Ikeda, H., Ishikawa, J., Hanamoto, A. "Genome sequence of an industrial microorganism ''Streptomyces avermitilis'': Deducing the ability of producing secondary metabolites." ''The Kitasato Institute for Life Sciences'', Kitasato University, Tokyo. August 2001.]
(4) [http://www.pbf.hr/bioinformatika/Articles/Ikeda%20et%20al%202003.pdf Ikeda, H., Ishikawa, J., Hanamoto, A., Shinose, M.  "Complete genome sequence and comparative analysis of the industrial microorganism ''Streptomyces avermitilis''." ''Nature Biotechnology.'' May 2003. Vol 21, p. 526-531.]


Edited by Jennifer Woods, student of [mailto:ralarsen@ucsd.edu Rachel Larsen]
Edited by Jennifer Woods, student of [mailto:ralarsen@ucsd.edu Rachel Larsen]

Revision as of 16:29, 29 August 2007

A Microbial Biorealm page on the genus Streptomyces avermitilis

Classification

Bacteria; Actinobacteria; Actinobacteridae; Actinomycetales; Streptomycineae; Streptomycetaceae; Streptomyces; Streptomyces avermitilis

Species

NCBI: Taxonomy

Streptomyces avermitilis

Description and significance

Streptomyces avermitilis was first isolated in 1979 at Kitasato Institute from a soil sample collected at Kawana, Ito City, Shizuoka Prefecture, Japan. It was sent to Merck Sharp & Dohme Research Laboratories for screen testing. (1)

This particular Streptomyces species dwells in terrestrial soils and has a brownish-gray spore mass. The spores are spherical (as opposed to oval) with a smooth spore surface and come in chains of more than 15. The sporophores form spiral side branches on aerial mycelia. (1)

S. avermitilis is an important species to have its genome sequenced because it produces certain secondary metabolites, called avermectins, that have antihelmintic and insecticidal properties. (2)

Genome structure

The chromosome of Streptomyces avermitilis contains over 9 million base pairs (9.02-Mb), putting it at the top as one of the largest bacterial genomes sequenced as of yet. It also has a higher GC content (70.7%) than almost any other organism, making the S. avermitilis chromosome unique in its size and structure (3). This linear chromosome contains 7,574 open reading frames (ORFs), as well as unique terminal-inverted repeats at both ends that bind terminal proteins. Of the 7,574 ORFs, 60.2% (or 4,563) encode funtional proteins and about 35% (or 2,663) cluster into 721 paralogous families. Of these 721, two main gene families are represented -- one relating to membrane-spanning components of ABC transporters, and the other relating to two-component transcriptional regulator systems. These results suggest that at least a third of all S. avermitilis genes may have emerged as a result of gene duplication during evolution (4).

Comparing the genomes of S. avermitilis and S. coelicolor A3(2) revealed a 6.5-Mb highly conserved internal region where all the essential genes are located (SAV1625-7142 in S. avermitilis). This region is structurally similar to other circular bacterial chromosomes, implying that this 6.5-Mb internal region may be the underlying backbone of all Streptomyces chromosomes and may have evolved from an ancestor common to all bacteria with circular chromosomes. Conversely, there are also variable, less conserved regions found near both telomeres. More than half the genes related to secondary metabolism (17 out of 30) were found in subtelomeric regions, while no known essential genes were found there (4).

S. avermitilis also contains the plasmid SAP1. SAP1 has 96 ORFs, 34.4% (or 33) of which encode funtional proteins (4).

Overall, the gene content of S. avermitilis suggests that its genome may have evolved by acquisition of novel gene functions that aided in its adaption to the intense competition, unpredictable fluctuation of nutrients, and extremely variable physical conditions of soil environments (4).

Cell structure and metabolism

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

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

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

References

(1) Burg, R., Miller, B., Baker, E., Birnbaum, J. et. al. "Avermectins, New Family of Potent Anthelmintic Agents: Producing Organism and Fermentation." Antimicrobial Agents and Chemotherapy. March 1979. Vol 15, No 3, p. 361-367.

(2) Demain, A. "Pharmaceutically active secondary metabolites of microorganisms." Appl. Microbiol. Biotechnol. 1999. Vol 52, p. 455-463.

(3) Omura, S., Ikeda, H., Ishikawa, J., Hanamoto, A. "Genome sequence of an industrial microorganism Streptomyces avermitilis: Deducing the ability of producing secondary metabolites." The Kitasato Institute for Life Sciences, Kitasato University, Tokyo. August 2001.

(4) Ikeda, H., Ishikawa, J., Hanamoto, A., Shinose, M. "Complete genome sequence and comparative analysis of the industrial microorganism Streptomyces avermitilis." Nature Biotechnology. May 2003. Vol 21, p. 526-531.

Edited by Jennifer Woods, student of Rachel Larsen