Magnetosomes are cell membrane invaginations organized by the actin-like protein MamK

Science. 2006 Jan 13;311(5758):242-5. doi: 10.1126/science.1123231. Epub 2005 Dec 22.


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 organized into chains. Thus, it seems that prokaryotes can use cytoskeletal filaments to position organelles within the cell.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actins / chemistry
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / physiology*
  • Cell Membrane Structures / chemistry
  • Cell Membrane Structures / physiology
  • Cell Membrane Structures / ultrastructure*
  • Cryoelectron Microscopy
  • Ferrosoferric Oxide
  • Magnetospirillum / cytology
  • Magnetospirillum / genetics
  • Magnetospirillum / physiology
  • Magnetospirillum / ultrastructure*
  • Mutation
  • Organelles / chemistry
  • Organelles / physiology
  • Organelles / ultrastructure*


  • Actins
  • Bacterial Proteins
  • Ferrosoferric Oxide