Most bacteria have a highly organized subcellular architecture to control cell shape, cell division and chromosome segregation. We study the structure and function of a unique bacterial organelle, magnetosome, which functions as a cellular compass to navigate along the Earthfs magnetic field. Magnetosomes are found in various kinds of magnetotactic bacteria such as Magnetospirillum magnetotacticum and consist of membrane-enclosed biomineralized magnetite crystals that are assembled into a straight chain with some structures such as cytoskeletal filaments, magnetosomal matrix, and interparticle connection. Interestingly, the magnetosomes are positioned at the center of the cell, along the long axis of the cell in Magnetospirillum species to donate the half of the chained magnetosomes to the daughter cells. How do the bacteria synthesize the magnetosome, construct the chained structure and control the positioning in the cell?@
Ongoing Research: In Biomolecule & Cell Research Division, we are pioneering biological phenomena and biological samples for bio-AFM studies. We have studied the localization of a novel prokaryotic actin homologue, MamK, which forms cytoskeletal filament to support the bacterial organelle magnetosomes. Immunostaining studies showed a linear distribution of MamK in the cell and of MamK in association with magnetosomes [J.Bact., 189: 8737-8740 (2007)]. On the other hand, we have succeeded in visualization of the magnetosomes using atomic force microscopy (AFM) [Proc. Natl. Acad. Sci. USA, 107: 9382-9387 (2010)]. We are now going to visualize the MamK polymerization process into filamentous bundles with AFM in the presence or absence of magnetosomes to investigate the interaction between magnetosomes and the bacterial actin-like cytoskeleton.
T. Hino, Y. Matsumoto, S. Nagano, H. Sugimoto, Y. Fukumori, T. Murata, S. Iwata, and Y. Shiro gStructural basis of biological N2O generation by bacterial nitric oxide reductaseh, Science, 330:1666-1670 (2010).
D. Yamamoto, T. Azuma, T. Uchihashi, H. Sasaki, H. Watanabe, T. Ando, and Y. Fukumori, gVisualization and structural analysis of the bacterial magnetic organelle magnetosome using atomic force microscopyh, Proc. Natl. Acad. Sci. USA, 107: 9382-9387 (2010).
A. Taoka, C. Umeyama, and Y. Fukumori, gIdentification of iron transporters expressed in the magnetotactic bacterium Magnetospirillum magnetotacticumh, Cur. Microbiol. 58: 177-181 (2009).
N. Numoto, T. Nakagawa, A. Kita, Y. Sasayama, Y. Fukumori and K. Miki, gStructural basis for the heterotropic and homotropic interactions of invertebrate giant hemoglobinh Biochemistry, 47: 11231-11238 (2008).
Y. Fukumori and A. Taoka, gMagnetotactic bacteria's organella, magnetosome-localization, and cytoskeletonh Tanpakushitsu Kakusan Koso, 53:1746-1751 (2008).
A. Taoka, R. Asada, LF. Wu and Y. Fukumori Y, gThe Polymerization of Actin-Like Protein MamK Associated with Magnetosomesh, J. Bacteriol., 189: 8737-8740 (2007).
N. Pradel, CL. Santini, A. Bernadac, Y. Fukumori and LF. Wu, gBiogenesis of actin-like bacterial cytoskeletal filaments destined for positioning prokaryotic magnetic organellesh, Proc. Natl. Acad. Sci. USA, 103: 17485-17493 (2006).
A. Taoka, R. Asada, H. Sasaki, K. Anzawa, L.F. Wu, and Y. Fukumori, gSpatial localizations of Mam22 and Mam12 in the magnetosomes of Magnetospirillum magnetotacticumh, J.Bacteriol., 188, 3805-3812 (2006).
N. Numoto, T. Nakagawa, A. Kita, Y. Sasayama, Y. Fukumori and K.Miki, gStructure of an extracellular giant hemoglobin of the gutless beard worm Oligobrachia mashikoih, Proc. Natl. Acad. Sci. USA, 102, 14521-14526 (2005).