Place: Kleiner Physik-Hörsaal, Geschwister-Scholl-Platz
Date: 05.06.09, Time: 15:30 h
Making nanomagnets by microbes: The biomineralization of magnetosomes in bacteria
Prof. Dirk Schüler
Fakultät für Biologie, Ludwig Maximilians-Universität München, Biozentrum Planegg-Martinsried
The biomineralization of magnetosomes is an intriguing example for the biogenic synthesis of a hierarchical self-assembled nanostructure. In magnetotactic bacteria these specialized membrane-enveloped organelles serve as navigational tools for orientation along geomagnetic field lines. Magnetosome formation is a complex biological process, and genes and poteins controlling intracellular differentiation, magnetite crystallization, and chain assembly are under our current investigation. Bacterial magnetic nanoparticles are also of interest for biotechnological and biomedical applications as they represent a novel class of small (30-45 nm), uniform particles with defined magnetic and crystalline characteristics. As the size and shape of magnetite crystals as well as the composition of the enveloping membrane are under genetic control, this provides the opportunity to design magnetic nanoparticles with altered physical and biochemical characteristics. For instance, genetic engineering is being used for in vivo functionalization of magnetosomes, such as the introduction of biomolecular coupling groups, fluorescence markers, and other functional moieties to the magnetosome membrane. Understanding the biomineralization process at the molecular level can also be used for the synthesis of size and shape-adjusted magnetosome particles by the controlled expression of specific proteins that regulate the size of growing magnetite crystals. Finally, highly ordered chains of intracellular magnetic nanoparticles represent one of the highest structural levels found in a prokaryotic cell. Assembly of bacterial magnetosome chains is controlled at the genetic and structural level and involves the action of specialized cytoskeletal structures, which could be applied to the in vitro formation of organized magnetic nanostructures.