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      MamY is a membrane-bound protein that aligns magnetosomes and the motility axis of helical magnetotactic bacteria

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          To navigate within the geomagnetic field, magnetotactic bacteria synthesize magnetosomes, which are unique organelles consisting of membrane-enveloped magnetite nanocrystals. In magnetotactic spirilla, magnetosomes become actively organized into chains by the filament-forming actin-like MamK and the adaptor protein MamJ, thereby assembling a magnetic dipole much like a compass needle. However, in Magnetospirillum gryphiswaldense, discontinuous chains are still formed in the absence of MamK. Moreover, these fragmented chains persist in a straight conformation indicating undiscovered structural determinants able to accommodate a bar magnet-like magnetoreceptor in a helical bacterium.

          Here, we identify MamY, a membrane-bound protein that generates a sophisticated mechanical scaffold for magnetosomes. MamY localizes linearly along the positive inner cell curvature (the geodetic cell axis) likely by self-interaction and curvature sensing. In a mamY deletion mutant, magnetosome chains detach from the geodetic axis and fail to accommodate a straight conformation coinciding with reduced cellular magnetic orientation. Co-deletion of mamKY completely abolishes chain formation, whereas upon synthetic tethering of magnetosomes to MamY, the chain configuration is regained, emphasizing the structural properties of the protein. Our results suggest MamY as membrane-anchored mechanical scaffold essential to align the motility axis of magnetotactic spirilla with their magnetic moment vector and to perfectly reconcile magnetoreception with swimming direction.

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          Most cited references 57

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                Author and article information

                [1 ]Department of Microbiology, University of Bayreuth, Bayreuth, Germany
                [2 ]Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Planegg-Martinsried, Germany
                [4 ]Department of Biology I, Ludwig-Maximilian-University Munich, Planegg-Martinsried, Germany
                Author notes
                [* ]Corresponding author and lead contact: Dr. Frank D. Müller, Department of Microbiology, University of Bayreuth, 95447 Bayreuth, Germany. frank.mueller@

                Present address: European Molecular Biology Laboratory, Heidelberg, Germany.


                Present address: Thermo Fisher Scientific (formerly FEI Company), Eindhoven, The Netherlands.


                Present address: Bundeswehr Institute of Microbiology, Bundeswehr, Munich, Germany.

                Nat Microbiol
                Nat Microbiol
                Nature microbiology
                12 June 2019
                29 July 2019
                November 2019
                29 January 2020
                : 4
                : 11
                : 1978-1989

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