Magnetotactic bacteria (Magnetospirillum sp. AMB-1): iGEM Research overview
First found at the bottom of a pond at Woods Hole in 1975 (Blakemore, 1975) the magnetotactic bacteria Magnetospirillum sp. AMB-1 is “easy to detect in samples collected from natural habitats without isolation and cultivation” (Moench, and Konetzka, 1978) and its genome was sequenced last year. (Matsunaga, and Okamura, et al, 2005) The bacteria that produces magnetite particles allowing them to align themselves with the earth’s magnetic field and providing a mechanism for them to move deeper into the ground and away from high oxygen environments (Simmons, Bazylinski, and Edwards, 2006). They are naturally found in oxic-anoxic transition zones (OATZ), which is the transition zone between water and sediment (Bazylinski, and Frankel, 2004).
The nature of the research is to use the magnetosomes, the parts containing the magnetic particles, for protein targeting. It has previously been shown that for visualization, luciferase can be targeted to the outside of the magnetosome by genetic insertion (Matsunaga, and Togo, et al, 2000), we propose to attempt to attach other proteins to the magnetosome. These fusion proteins could then be isolated from the bacterium and used for tissue specific targeting. We intend to start this investigation by tagging the magnetosome with avidin, a glycoprotein with strong affinity to biotin (Vitamin B7) (Wilchek, and Bayer, 1988). We hope that the isolated magnetosomes can then be used as a cellular biotin reporter that could possibly be detected via magnetic resonance imaging. We plan to do this by creating a fusion protein of MagA, the gene that produces the magnetosome coating and the avidin gene, which has already been artificially synthesized. [for sequence see http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=92791046]
A second potential use of this technology could be to tag the magnetosome with a protein attracted to cancerous cells, the magnetosome could then be used to tag cancer cells, by heating the magnetic particles up the cancerous cells could be destroyed.
A thorough review of magnetotactic bacteria is attached and can be found here:(Bazylinski, and Frankel, 2004) http://www.nature.com/nrmicro/journal/v2/n3/full/nrmicro842_fs.html
To create magnetosomes covered in Avadin. The basic idea is to create a fusion protein from MagA and Avadin, then isolate the magnetic particles, which will now be coated in avadin. Avadin forms one of the strongest bindings known with the molecule biotin.
Bayer, E. A. and Wilchek, M. (1978). The avidin-biotin complex as a tool in molecular biology. Trends Biochem. Sci. 3, N237-N239.
- http://www.weizmann.ac.il/Biological_Chemistry/scientist/Bayer/BayerAvidin.html great review
- http://www.avidity.com/apps.html current applications of tagging biotin
- Artifical synthesized Gene coding for avidin
- Bazylinski, D.A., and Frankel, R.B. (2004). Magnetosome formation in prokaryotes. Nat. Rev. Microbiol. 2, 217-230.
- Blakemore, R. (1975). Magnetotactic bacteria. Science 190, 377-379.
- Matsunaga, T., Okamura, Y., Fukuda, Y., Wahyudi, A.T., Murase, Y., and Takeyama, H. (2005). Complete Genome Sequence of the Facultative Anaerobic Magnetotactic Bacterium Magnetospirillum sp. strain AMB-1. DNA Res. 12, 157-166.
- Matsunaga, T., Togo, H., Kikuchi, T., and Tanaka, T. (2000). Production of luciferase-magnetic particle complex by recombinant Magnetospirillum sp. AMB-1. Biotechnol. Bioeng. 70, 704-709.
- Moench, T.T., and Konetzka, W.A. (1978). A novel method for the isolation and study of a magnetotactic bacterium. Arch. Microbiol. 119, 203-212.
- Simmons, S.L., Bazylinski, D.A., and Edwards, K.J. (2006). South-seeking magnetotactic bacteria in the Northern Hemisphere. Science 311, 371-374.
- Wilchek, M., and Bayer, E.A. (1988). The avidin-biotin complex in bioanalytical applications. Anal. Biochem. 171, 1-32.