STRUCTURE-FUNCTION STUDIES OF IRON BIOMINERALIZING MAGNETOSOME ASSOCIATED PROTEINS

Magnetic nanoparticles are key components in many technologies and biotechnologies. Yet, it is not easy to modify them and control their shape and size. Natural organisms that perform such control are magnetotactic bacteria. Magnetotactic bacteria navigate along geomagnetic fields by forming magnetosomes chains. Magnetosomes are intracellular membrane-enclosed, nanometer-sized crystals of the magnetic iron mineral magnetite (Fe₃O₄) or gregite (Fe3S4). Biomineralization of magnetite within these unique prokaryotic organelles involves the nucleation and controlled growth of magnetite via magnetosome magnetite-binding proteins. In this work, we studied the structure-function relationships of Mms6, a magnetosome-associated protein, which is suggested to be involved in magnetite biomineralization. We used a novel approach in which scaffold proteins such as ferritin and MBP were linked to Mms6 to promote their study. Using this approach we were able, for the first time, to shed light on Mms6 functional component and show its effect on magnetite binding and mineralization. Moreover, such chimeras can be used as biotechnological tool for MRI applications as we demonstrated in vivo using the ferritin-Mms6 chimera.