Molekulare und strukturelle Untersuchungen zur Bildung von Magnetosomen und zur Assemblierung von Magnetosomenketten in Magnetospirillum gryphiswaldense

Abstract

For navigation along the earth's magnetic field Magnetospirillum gryphiswaldense and related magnetotactic bacteria (MTB) produce magnetosomes, which are organelles formed of the magnetosome membrane (MM) enclosing crystals of the magnetic iron oxide magnetite. The magnetosomes are usually aligned in a chain to ensure efficient geomagnetic field orientation. The MM harbors a set of MTB-specific proteins whose precise roles in magnetosome formation and alignment have remained largely elusive. This work reports on the functional analysis of the MM protein MamJ, which contains a conspicuous acidic repetitive domain and the small hydrophobic MamGFDC proteins, which constitute the most abundant proteins associated with the MM. The MamJ protein was found essential for magnetosome chain formation as it prevents spontaneous agglomeration of magnetosomes by aligning them along a novel cytoskeletal filament in M. gryphiswaldense. The MamGFDC proteins were found to control the growth of magnetite crystals of M. gryphiswaldense by an as-yet unknown mechanism.