Tropheryma whipplei: Difference between revisions

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Genus: Tropheryma  
Genus: Tropheryma  
Species: Whipplei
Species: Whipplei
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==Description and significance==
==Description and significance==

Revision as of 05:02, 4 June 2007

Classification

Higher order taxa

Cellular Organisms; Bacteria; Actinobacteria; Actinobacteria (class); Actinobacteridae; Actinomycetales; Micrococcineae; Cellulomonadaceae; Tropheryma; Tropheryma Whipplei

Genus

Genus: Tropheryma Species: Whipplei

Description and significance

The reason why Troperyma Whipplei is so damaging to the human body is because it is the master of disguise. Very little is known of its physiology; however, it has a thick cell wall and an atypical envelope. It exhibits giant rope-like structures when in culture that are similiar-looking to Mycobacterium Tuberculosis. As themaster of disguise, it not only has its own changing set of proteins encoded by its own genome, but also hides itself in the membranes stolen from the host cells. This makes it all the more hard to identify as a foreign body in the host, which is the human body. Even though, in actuality, it causes very few cases of diseases, it is still remarkable that this tiny genome has such a grand capability of manipulating itself and using its environment to hide and how rapidly this change can occur. It is for this very reason that it is important enough to have its genome sequenced. It was first described as the initiator of Whipple's Disease by George Whipple in 1907; however, it was not a reproducible culture until 2000, when it was then grown in human fibroblasts.


Description

False-colour image of Tropheryma whipplei in which the genome is represented by the yellow-coloured regions. Courtesy Dr. Axel von Herbay.



Description


Fluorescent in situ hybridisation of a small intestinal biopsy in a case of Whipple's disease (confocal laser scanning microscopy). Tropheryma whipplei rRNA is blue, nuclei of human cells are green and the intracellular cytoskeletal protein vimentin is red. Magnification approximately 200 x. From: Fredricks DN, Relman DA. J Infect Dis 2001; 183: 1229-37. Reproduced with permission from University of Chicago Press. Copyright: Infectious Diseases Society of America, 2001.



Genome structure

Troperyma Whipplei is the only reduced genome species, being less than 1Mb within the Actinobacteria. Though this human pathogen is small, it has a sequence of 927, 303 bp and is a circular genome. It encodes 808 predicted protein-coding genes. It has several specific genome features including: deficiencies in amino acid metabolism; a mutation in DNA gyrase, which leads to the potential resistance to quinolone antibiotics; lacks a clear thioredoxin and thioredoxin reductase homologs. A large chromosomal inversion was discovered when two available Tropheryma Whipplei genome sequences were aligned. The extremeties are located within two paralogous genes, which belong to a large cell-surface protein family defined by the presence of a common repeat highly conserved at the nucleotide level. It is these repeats that seem to spark a rearrangements in the Trophermya Whipplei. This, in turn, causes a varying expression of cell surface proteins, and thereby may be a new mechanism it uses to evade host defenses.

Cell structure and metabolism

Of course the main interesting feature of Trophermya Whipplei is its ability to be the master of disguise, as discussed above, as well as the fact that it is the only human pathogen of the Actinobacteria that has a reduced genome. Its genome revealed that this bacterium in particular is well equipped for energy metabolism, nucleotide biosynthesis, and regulatory processes in comparison with microbes of a similar genomic size.


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

[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 Sophia Gevorkian, student of Rachel Larsen and Kit Pogliano.