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Published Online December 22, 2005
Science DOI: 10.1126/science.1123231

Reports

Submitted on November 30, 2005
Accepted on December 12, 2005

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

Arash Komeili 1*, Zhuo Li 2, Dianne K. Newman 3, Grant J. Jensen 2

1 Divisions of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA; Present address: Department of Plant and Microbial Biology, University of California, Berkeley, Mail Code 3102, Berkeley, CA 94720, USA.
2 Divisions of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
3 Divisions of Geological and Planetary Sciences; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.

* To whom correspondence should be addressed.
Arash Komeili , E-mail: komeili{at}nature.berkeley.edu

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.


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Science. ISSN 0036-8075 (print), 1095-9203 (online)