Thermus aquaticus
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| Thermus aquaticus | ||||||
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Description and significance
[1] Thermus Aquaticus isolated in 1969 by brocks and Freee of University of Indiana have proved to be of extreme importance in the field of Microbiology due to it's thermostability. It is a gram negative bacteria both motile (presence of a flagellum) or immotile.
Genome structure
This section discusses the genome structure Thermus Aquaticus contains pillus like structures used in conjugation. 12 genes in 3 loci were found to encode for preplin like proteins essential for natural transfomation. Core enzyme Taq Rna polymerase consists of 4 different subunits: Alpha(2), Beta, Beta prime, and Omega, complexed with Sigma factor. The enzyme is claw shaped with a clamp that closes on an internal channel containing Magnesium ions and the active site. Sigma interacts with core enzyme and specifically binds to promoter to widen the channel allowing DNA into interior of polymerase complex
Cell structure and metabolism
Thermus Aquaticus not only can function at high temperatures but they thrive in higher temperatures. Optimum growth is seen between 60 and 75 degrees celsius (could go as low as 35
degrees celsius to as high as 85 degrees celsius). PH ranges from 7.5 to 8.0 generally but some strains could be between 5.1 to 9.5. This organism is a chemotroph using
carbohyddrates, amino acids, caboxylic acids and peptides for growth. Monosaccharides are generally used for carbons sources but sucrose, maltose(Icelandic stains) and even some
fewer strains use glucose. There is also a variance in the proteins isolated from different strains; Elastin, Fibrin and Casein. Not all strains can hydrolize all substrates.
Membranes of these proteins are remarkably temperature stable and the heat stability of the enzymes and proteins synthesis systems allow them to function efficiently at high
tempratures. Many factors contribute to the stability of the proteins:
1) Highly organized hydrophobic interiors 2) More hydrogen bonds and presence of other non covalent bonds strengthen the structure. 3) Larger quantities of amino acids like Proline make peptide chain less flexible. 4) Proteins aided and stabilized by special chaperone proteins. 5) Some evidence that DNA is stabilized by histone like proteins. 6) Their membrane lipids tend to be more saturated and more branched and posses higher molecular weight resulting in a higher melting point and in turn more thermostable.
Ecology
u Aquaticus was first isolated in the Great Fountain region of Yellowstone National Park from neutral and alkaline springs in 1969 by Brocks and Freeze. This discovery disproved the previous beliefs that bacteria could not function properly at higher temperatures. After this discovery, some strains of Thermus Aquaticus were discovered in hot springs in Iceland.
CONTROVERSY: After the isolation of Thermus Aquaticus, samples of it were deposited in the American Type Culture Collection, which is a public repository and other scientists were able to obtain samples and do more research. By about 1980's it was pretty obvious the potential for commercialising the enzymes from this organism were extremely high and lots of profits and revenue were involved. A Swiss pharmacuedical copany called Laroche patened it and so the National Park Systems were not receiving any; of the profits eventhough the organism was isolated at a national park which is public property and so this is called "great Taq ripoff". Since then researches at the parks sign an agreement of "benefits sharing" so portions of profits can get back to park services.
Pathology
Thermus Aquaticus has not been associated with pathogenecy.
Application to Biotechnology
Enzymes derived from Thermus Aquaticus have had an incredibly important role in facilitating many aspects of biotechnology correlated with DNA amplification and enabling researchers
to study proteins and enzymes under conditions not possible before and this is all due to the thermostability of the protiens and there ability to function at even higher rates at high
temperatures. Some of the isolated enzymes and their roles in facilitaitng applications in biotechnology are as follows:
1) Adolase- a themostable enzyme (protein enzyme that functions well at high temperature. 2) RNA polymerase- first polymerase isolated from Taq in1974. 3) Restriction Endonucleases 4) DNA polymerase- isolated in 1976, could be isolated in purer form and later discoveered to be used in PCR, for amplifying short segments of DNA (before the discovery of the Taq DNA, enzymes needed to be added after each cycle of denaturing of DNA, but with the use of the Taq DNA polymerase it was not necessary anymore.) This enzyme was soon cloned, sequenced, and produced in mass quantities for commercial sale. 5) Other enzymes with high optimal temperatures allowing researchers to study them in extreme conditions are:DNA ligase, Alkaline Phosphotase, NADH Oxidase, Isocitrade, Dehydrogenase, Amylomaltase and Fructose1,6-Biophosphate-Dependedent L Lactate Dehydrgenase.
Current Research
References
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