[ODP-064] Magnetosomal protein MamJ regulates polymerization of MamK cytoskeleton for magnetosome positioning
Magnetotactic bacteria (MTB) use magnetic organelle called magnetosome which are composed of a magnetite crystal surrounded by a lipid membrane. Magnetosomes function as magnetic sensor to navigate them along the geomagnetic field to reach the microaerobic environment effectively. In the MTB cells, magnetosomes are positioned in a chain-like arrangement along long axis of their cells. Although two magnetosome-associated proteins, MamK and MamJ, are essential for the magnetosome arrangement, the detailed mechanism of magnetosome arrangement has not been clarified. Here, we purified both of monomeric MamK and MamJ. We analyzed effects of MamJ on polymerization of MamK filaments. We compared structures of MamK filaments polymerized with and without MamJ using fluorescence microscopy and High-speed AFM. The microscopic observations indicated that MamJ prevents forming large bundles of MamK filaments. More than 60% of MamK filaments were longer than 500 nm when MamK polymerized without MamJ, whereas MamK forms short straight filaments when it polymerized with MamJ. The average length of MamK filaments polymerized with MamJ was about 100 nm. These results suggested that MamJ effects on the property of MamK polymerization and forms short MamK filaments. We will discuss about the role of MamJ-MamK interaction on MamK polymerization.