Mycoplasma mobile

From MicrobeWiki, the student-edited microbiology resource

A Microbial Biorealm page on the genus Mycoplasma mobile

Classification

Higher order taxa

Cellular organisms; Bacteria; Firmicutes; Mollicutes; Mycoplasmatales; Mycoplasmataceae; Mycoplasma

Genus

Mycoplasma Mobile;


NCBI: Taxonomy

Description and significance

Mycoplasma mobile, a flask-shaped piscine mycoplasma (approximately 1.0 x 0.3 µm), is thought to be pathogenic and was first isolated from a tench fish host. Mycoplasma mobile is known for its gliding motility at speeds as fast as 7 µm/second. Many of the mycoplasma organisms have this gliding motility, defined as “a smooth translocation over a solid surface,” but none as extreme as the ability of Mycoplasma mobile. M. mobile has been observed to move in the direction of the tapered end of the cell, known as the “head,” and glides at high speeds without reversing directions or stopping. M. mobile has also been found to be very strong, able to “tow an erythrocyte roughly 10 times its size, without significant loss in speed and has been measured to exert up to 27 pN of force ability.” Because little has been discovered about the genes responsible for gliding motility, scientists thought it would be useful to sequence the complete genome and proteome of Mycoplasma mobile. They felt that comparing the genomic sequence of M. mobile to those of other immotile or slower-gliding mycoplasmas could help paint a clearer picture of the gliding mechanism. The results of these analyses leave open the possibility that gliding motility might have arisen independently more than once in the mycoplasma lineage.

Genome structure

The M. mobile genome consists of a single circular chromosome. It has been found to have 777,079 bp. Its GC content (24.9 %), is considered low compared other mycoplasmas, which are already typically GC-poor (24%–40%). Scientists investigating Mycoplasma mobile have found coding sequences for 635 proteins in the genome, 88% of which have been shown to be expressed proteins. M. mobile contains a single copy each of the 16S–23S–5S ribosomal DNAs. Unlike as found with other mycoplasma organisms such as the similar M. pulmonis, the 5S rDNA is not located within the 16S–23S rDNA operon, but is located about 180° away (with respect to the circular chromosome) from it. This is an implication that a major genome rearrangement may have occured about this axis. There was evidence for 28 tRNA genes in the M. mobile genome, the fewest of any organism reported at the time. Other unique features were discovered, including a long repeating unit of DNA of 2435 bp. This DNA unit is present in five copies which code for almost identical proteins, but are uniquely expressed. Many tandem duplications and evidence of lateral gene transfer are present in the M. mobile genome.

Cell structure and metabolism

Mycoplasmas are wall-less bacteria known for having small physical dimensions and genome sizes. Mycoplasma mobile is a flask-shaped mycoplasmas, and has been found to be a Gram-positive eubacteria. Scientists interested in the gliding motility of M. mobile have studied the genome but have not found genes similar to other forms of cell motility in bacteria such as flagellae or pili. They also did not find forms of motility similar to those of eukaryotes, such as genes encoding for myosin, kinesin, or actin, which have been found in genome sequences of other gliding mycoplasmas. What has been discovered is that gliding by M. mobile is an ATP-powered process and that M. mobile has several large ultrastructural proteins that help with surface adhesion. Because gliding is ATP powered, any proteins with ATPase functionality in the genome could be considered motility gene candidates. The metabolism of M. mobile, or basic breakdown of proteins, is like that of other mycoplasmas, but with an emphasis on protein synthesis and transport of compounds. M. mobile is able to metabolize glucose, sucrose, fructose, maltose/maltodextrin, xylose, and trehalose as energy sources. M. mobile should also be able to produce and use glycogen and starches, as can many other mycoplasma species. Fermenting of sugars appears to be the single method of producing ATP in M. mobile.

Ecology

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

Pathology

M. mobile is believed to be pathogenic, adapted to living on fish hosts. Four antibodies have been found on the cell surface. Its optimal growth occurs at around 20°C, lower than most other well-studied mycoplasmas, (around 37°C). Aside from the difference in optimal growth temperature its doubling time ( 10 h) is in the range of other mycoplasmas with mammalian hosts. M. mobile also contains a set of repetitive elements presumed to be a variable surface antigen. A correlation of mycoplasma pathogenicity with motility implies that motility is involved in the pathogeninc process.

Application to Biotechnology

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

Current Research

- M. mobile can be used as a microtransporter and run on a set track - a microrotary motor run by bacteria

..to be continued

References

Jaffe, J. D., Miyata, M. & Berg, H. C. (2004a). "Energetics of gliding motility in Mycoplasma mobile." J Bacteriol 186, 4254–4261.


Jaffe, J. D., Stange-Thomann, N., Smith, C., DeCaprio, D., Fisher, S., Butler, J., Calvo, S., Elkins, T., FitzGerald, M. G., Hafez, N., Kodira, C. D., Major, J., Wang, S., Wilkinson, J., Nicol, R., Nusbaum, C., Birren, B., Berg, H. C., and Church, G. M., (2004b). "The complete genome and proteome of Mycoplasma mobile." Genome Res 14, 1447–1461


Ohtani N., Miyata M. (2007)"Identification of a novel nucleoside triphosphatase from Mycoplasma mobile: a prime candidate motor for gliding motility." Biochem J. 2007 Apr 1; 403(1):71-7.


Hiratsuka Y., Miyata M., Uyeda T.Q.(2005)"Living microtransporter by uni-directional gliding of Mycoplasma along microtracks." Biochem Biophys Res Commun. 2005 May 27;331(1):318-24.


Kusumoto A., Seto S., Jaffe J.D., and Miyata M., 2004. "Cell surface differentiation of Mycoplasma mobile visualized by surface protein localization." Microbiology 150 (2004), 4001-4008; DOI 10.1099/mic.0.27436-0


Hiratsuka Y., Miyata M., Tada T., and Uyeda T.Q.P., 2006. "A microrotary motor powered by bacteria" PNAS. 2006 September 12; 103(37): 13618-13623.


Edited by student of Rachel Larsen and Kit Pogliano