Magnetosome biogenesis in magnetotactic bacteria

The orientation of magnetotactic bacteria is based on the presence of unique organelles, magnetosomes, which are intracellular, membrane-enclosed, nanometre-sized crystals of magnetic iron minerals.In the past decade, substantial advances have been made in our understanding of magnetosome biogenesis using two genetically tractable Magnetospirillum species.Magnetosome biogenesis entails the invagination of the magnetosome membrane, recruitment of specific proteins, iron transport and redox-controlled biomineralization of magnetite crystals; magnetosomes are then assembled and positioned into well-ordered linear chains that are among the most complex structures seen in prokaryotic organisms.Key functions of magnetosome biogenesis are encoded by about 30 genes that are clustered in a genomic 'magnetosome island', although additional auxiliary functions are contributed by general cellular metabolic and regulatory pathways, including aerobic and anaerobic respiration.A non-magnetotactic bacterium has recently been 'magnetized' through the heterologous expression of genes that encode the magnetosome biogenesis pathway, which is a proof-of-principle demonstration that non-magnetotactic bacteria that are more facile for laboratory investigation could be 'magnetized' to provide new models for genetic dissection and synthetic biology.Bacterial magnetosomes are promising nanomaterials for various bioremediation, biomedical and bionanotechnological applications.