Magnetosomes Are Cell Membrane Invaginations Organized by the Actin-Like Protein MamK

@article{Komeili2006MagnetosomesAC,
  title={Magnetosomes Are Cell Membrane Invaginations Organized by the Actin-Like Protein MamK},
  author={Arash Komeili and Zhuo-Yue Li and Dianne K. Newman and Grant J. Jensen},
  journal={Science},
  year={2006},
  volume={311},
  pages={242 - 245}
}
Magnetosomes are membranous bacterial organelles sharing many features of eukaryotic organelles. Using electron cryotomography, we found that magnetosomes are invaginations of the cell membrane flanked by a network of cytoskeletal filaments. The filaments appeared to be composed of MamK, a homolog of the bacterial actin-like protein MreB, which formed filaments in vivo. In a mamK deletion strain, the magnetosome-associated cytoskeleton was absent and individual magnetosomes were no longer… Expand
Structure of the magnetosome‐associated actin‐like MamK filament at subnanometer resolution
TLDR
While MamK is closest in sequence to the bacterial actin MreB, the longitudinal contacts along each MamK strand most closely resemble those of eukaryotic actin, which gives rise to the nonstaggered architecture. Expand
Biogenesis and subcellular organization of the magnetosome organelles of magnetotactic bacteria.
TLDR
A number of studies have elucidated the possible factors involved in the formation of the magnetosome membrane and biomineralization of magnetic minerals and highlight some of these recent advances with a particular focus on the cell biology of magnetosomes formation. Expand
Polymerization of the Actin-Like Protein MamK, Which Is Associated with Magnetosomes
TLDR
It is demonstrated that MamK polymerizes into filamentous bundles in vitro and is used as an antigen to generate the anti-MamK antibody. Expand
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TLDR
The results demonstrate the mechanism of biogenesis of prokaryotic cytoskeletal filaments that are structurally and functionally distinct from the known MreB and ParM filaments and prove the authenticity of the MamK filaments. Expand
Segregation of prokaryotic magnetosomes organelles is driven by treadmilling of a dynamic actin-like MamK filament
TLDR
A novel mechanism for prokaryotic organelle segregation is proposed that, similar to the type-II bacterial partitioning system of plasmids, relies on the action of cytomotive actin-like filaments together with specific connectors, which transport the magnetosome cargo in a fashion reminiscent of eukaryoticActin-organelle transport and segregation mechanisms. Expand
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TLDR
The results suggest MamY is membrane-anchored mechanical scaffold that is essential to align the motility axis of magnetotactic spirilla with their magnetic moment vector and to perfectly reconcile magnetoreception with swimming direction. Expand
The Bacterial Actin MamK
TLDR
It is demonstrated that MamK is an ATPase that, in the presence of ATP, assembles rapidly into filaments that disassemble once ATP is depleted, which is consistent with observations indicating that accessory factors are required for filament disassembly and for spatial organization of filaments in vivo. Expand
Prokaryotic Cytoskeletons
As discovered over the past 25 years, the cytoskeletons of bacteria and archaea are complex systems of proteins whose central components are dynamic cytomotive filaments. They perform roles in cellExpand
Greigite magnetosome membrane ultrastructure in 'Candidatus Magnetoglobus multicellularis'.
TLDR
Observations of cell membrane invaginations, the trilaminar membrane structure of immature magnetosomes, and empty vesicles together suggested that greigite magnetosome formation begins by invagination of the cell membrane, as has been proposed for magnetite magnetOSomes. Expand
Genetics and cell biology of magnetosome formation in magnetotactic bacteria
TLDR
A total of 28 conserved genes present in various magnetic bacteria were identified to be specifically associated with the magnetotactic phenotype, most of which are located in the genomic magnetosome island. Expand
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