Mycobacterium tuberculosis: Difference between revisions

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==References==
==References==
[Sample reference] [http://ijs.sgmjournals.org/cgi/reprint/50/2/489 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.]
Pascopella L, Collins FM, Martin JM, Lee MH, Hatfull GF, Stover CK, Bloom BR, Jacobs WR Jr. Use of in vivo complementation in Mycobacterium tuberculosis to identify a genomic fragment associated with virulence. Infect Immun. 1994;62:1313–1319. [PubMed]
 


Edited by student of [mailto:ralarsen@ucsd.edu Rachel Larsen] and Kit Pogliano
Edited by student of [mailto:ralarsen@ucsd.edu Rachel Larsen] and Kit Pogliano

Revision as of 09:16, 3 May 2007

A Microbial Biorealm page on the genus Mycobacterium tuberculosis

Classification

Higher order taxa

Domain: Bateria; Phylum: Actinobacteria; Class: Actinobacteria; Order: Actinomycetales; family: Mycobacteriaceae; Genus: Mycobacterium;

Species

The mycobacterium tuberculosis complex (MTC) consists of Mycobacterium africanum, Mycobacterium bovis, Mycobacterium canettii, Mycobacterium microti, Mycobacterium pinnipedii, Mycobacterium tuberculosis.

Description and significance

Mycobacterium tuberculosis is a pathogen that is capable of surviving in various harsh conditions. It infects a third of the human population and causes at least two millioin deaths each year.It infects both human and non-human primates as well as other animals such as dogs, cats, pigs birds and wild animals.

Genome structure

Mycobacterium tuberculosis has a circular DNA about 4,200,000 nucleotides long. The GC content is about 65%.

The four speices of the mycobacterium tuberculosis complex show a 95-100% DNA relatedness based on studies of DNA homology, and the sequence of the 16S rRNA gene are exactly the same for all five species. So some scientists should be grouped as a single speices while others argue that they should be grouped as varieties or subspecies of M. tuberculosis.

Cell structure and metabolism

The M. tuberculosis cell wall contains three classes of mycolic acids: -, keto-, and methoxymycolates, where -Mycolates are the most abundant form in M. tuberculosis. The cell wall also contains lipid complexes include acyl glcolipids and other complext free lipids and sulfolipids. There are porins in the membrane to facilitate transport. Beneath the cell wall, there are layers of arabinogalactan and peptidoglycan that lie just above the plasma membrane.

The M. tuberculosis genomes encodes about 190 transcriptional regulators, including sigma factors. Several regulators have been found to respond to environmental distress, such as extreme cold or heat, iron starvation, and oxidative stress.

Ecology

Mycobacterium tuberculosis has been found in early hominids origniated in East-Africa. Therefore, studying the population structure of the species might provide insights about homo sapiens's migratory and emographic history. Mycobacterium tuberculosis has also been known to be drug resistance. Understanding the biology of drug resistance enables researchers to predict and prevent furture spread of resistant strains.

Pathology

Mycobacterium tuberculosis infects both human and non-human primates as well as other animals such as dogs, cats, pigs birds and wild animals by producing pili that are recognized by IgG antibodies. Once inside the host cell, it is able to survive and replicate within the macrophages of the host by avoidng lysosomal fusion with the mycobacteria-containing phagosome. However, most of the host-microbe interaction is unknown.

Application to Biotechnology

Gene for histone-like protein (hupB [Rv2986c]) of Mycobacterium tuberculosis had been used to dinstinguishing members of the MTB complex from other mycobaacterial species and differentiating between members within the complex.

In addition, in vivo complementation in mycobacterium tuberculosis strain H37Ra can be used to identify genomic fragment associated with virulence.

Current Research

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

Since the pathogen-host interaction of Mycobacterium tuberculosis is still unknown, much of the current research is geared towards the understanding of the mechanism of virulence. For example, one such research showed that prokaryotic- and eukaryotic-like isoforms of the glyozxylate cycle enzyme isocitrate lyase (ICL) are jointly required for fatty acid catabolism and virulence in Mycobacterium tuberculosis. This discovery provide insight such as drugs that are glycoxylate cycle inhibitors could be used to treat tuberculosis.

References

Pascopella L, Collins FM, Martin JM, Lee MH, Hatfull GF, Stover CK, Bloom BR, Jacobs WR Jr. Use of in vivo complementation in Mycobacterium tuberculosis to identify a genomic fragment associated with virulence. Infect Immun. 1994;62:1313–1319. [PubMed]


Edited by student of Rachel Larsen and Kit Pogliano