A protease-mediated switch regulates the growth of magnetosome organelles in Magnetospirillum magneticum

Abstract

Significance Biomineralization, the process by which elaborate three-dimensional structures are built out of organic and inorganic molecules, is central to health and survival of many organisms. In some magnetotactic bacteria, the growth of magnetosome membranes is closely correlated to the progression of mineral formation. However, the molecular mechanisms of such regulation are not clear. We show that the serine protease MamE links magnetosome membrane growth to the controlled production of magnetite nanoparticles through the processing of mineral-associated MamD protein. Our results indicate that membrane growth directly controls mineral growth and shed light on how an organelle’s size can determine its physiological output. Manipulation of the MamE pathway may also open the door for control of nanoparticle size in future biotechnological applications.