Mycobacterium leprae

A Microbial Biorealm page on the genus Mycobacterium leprae

Classification

Higher order taxa

Bacteria; Actinobacteria; Actinobacteria; Actinobacteridae; Actinomycetales; Corynebacterineae; Mycobacteriaceae ; Mycobacterium [Others may be used. Use NCBI link to find]

Species

NCBI: Taxonomy

Mycobacterium leprae

Description and significance

Mycobacterium leprae is responsible for leprosy or Hansen's disease. Cases of leprosy have been recorded as early as 600 B.C. In 2004, The World Health Organization reported that there were 407,791 new cases of leprosy. Leprosy is a serious world issue, in Brazil, India, Democratic of Congo, Tanzania, Nepal, Mozambique, Madagascar, Angola and the Central African Republic leprosy is a major problem. Mycobacterium leprae is an intracellular bacterium, infecting nerve, skin and mucosal cells. In laboratory environments, Mycobacterium leprae is cultured on the feet of mice or on nine banded armadillos due to the inability to culture in vitro.

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated.

Genome structure

There are 3,268,203 nucleotides comprising the single circular chromosome of M. leprae. There are 2770 genes with in M. leprae. This is composed of coding for 1605 proteins and contains 1115 pseudogenes, primarily genes that were involved in metabolism but genes involved with DNA repair(mutT, dnaQ, alkA, dinX, and dinP genes) and detoxification(peroxidase genes). Many of the pseudogenes were involved in catabolism, the biosynthetic pathways tend to be well conserved. This was likely due to a number of recombination events, deletions and decay. Only 49% of the genome encodes for proteins. There is a 57% GC content. The genome was finished being sequenced in 10/02/2001 by the Sanger Institute.

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Cell structure and metabolism

Mycobacterium leprae is a acid fast gram positive bacterium. With a slow doubling time of 27 hours. This slow doubling time makes it paricularly hard to fight.

Many of the pseudogenes primarily occur in the metabolic pathways. Entire metabolic pathways have been lost to this genomic down sizing. M. leprae can no longer produce siderophores, a key part of oxidative, microaerophilic and anarobic chains. Many regulatory elements of metabolism have also been lost and also many catabolic pathways too. M. leprae is dependent on the host cell to provide many of the nutrients and metabolites.

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

[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". Metabolism in Mycobacterium leprae: its relation to other research on M. leprae and to aspects of metablism in other mycobacteria and intracellular parasitesInternational Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Walker, S., Lockwood, D. "Leprosy". Clinics in Dermatology. 2007. Volume 25. p. 165-172.

[1] Wheeler, P.R. "Metabolism in Mycobacterium leprae: its relation to other research on M. leprae and to aspects of metablism in other mycobacteria and intracellular parasites." International Journal of Leprosy and other Mycobacterial Disease. June 1984. Volume 2. p. 208-230.

[2] Franzblau, S.G., Harris, E.B. "Biophysical optima for metabolism of Mycobacterium leprae". Journal of Clinical Microbiology. June 1988. Volume 6. p. 1124-1129.

[3] Wheeler, P.R. "Metabolism in Mycobacterium leprae, M. tuberculosis and other pathogenic mycobacteria". British Medical Bulletin. 1988. Volume 44. p. 547-561. Edited by student of Rachel Larsen and Kit Pogliano