Arash Komeili

Assistant Professor
Ph.D.  Cell Biology    UCSF, 2001
B.S.    Biology    MIT, 1996

261A Koshland Hall #3102
Berkeley, California 94720-3102
komeili@berkeley.edu
office: 510-642-2140   lab: 510-642-2140   fax:  510-642-4995

     Recent publications      People

It has become increasing clear that bacterial cells are highly organized with many ultrastructural similarities to eukaryotic cells. In addition to a dynamic cytoskeleton composed of homologues of actin, tubulin and intermediate filaments, many bacteria also possess intracellular membranous organelles. Our lab uses magnetosomes as a model system for studying the molecular mechanisms of organelle biogenesis and maintenance in bacteria.

The magnetosome chains of magnetotactic bacteria are one of the best-studied examples of membranous bacterial organelles. Magnetosome chains (see figure to the right) contain 15-20 approximately 50-nm magnetite crystals that act like the needle of a compass to orient magnetotactic bacteria in geomagnetic fields, thereby simplifying their search for their preferred microaerophilic environments. The unique properties of magnetosomal magnetite crystals have drawn attention to their potential use in biotechnology, bioremediation, and geobiology and have made them a genetically tractable system for the study of biomineralization. In addition to these applications, the cell biological characteristics of magnetosomes make them ideal for the study of organelle biology in bacteria. Each magnetite crystal within a magnetosome is surrounded by a lipid bilayer, and specific soluble and transmembrane proteins are sorted to the magnetosome membrane. These results suggest that to build a magnetosome a bacterium must be able to generate a membranous comparmtent, target the appropriate set of proteins to this membrane and control their number and position within a cell.

My lab uses a combination of cell biological, genetic and biochemical approaches to define the physical characteristics of the magnetosome and identify key genes involved in controlling its production and function. Our earlier work showed that the magnetosome membrane is an independent organelle that pre-exists the formation of magnetite and that magnetite synthesis proceeds simultaneously from multiple adjacent magnetosomes. Recently, the work of several groups including ours has led to the identification of a large genomic region with many genes encoding proteins that are localized to the magnetosome and are essential for magnetite formation. The challenge now is to understand the specific functions of these genes and how their products interact to form a magnetosome.

Komeili A. Molecular mechanisms of magnetosome formation. Annual Review of Biochemistry. 76: 351-366 (2007). Reprint.

Komeili A. Cell biology of magnetosome formation. In Magnetoreception and Magnetosomes in Bacteria. Ed. D. Schüler. Berlin: Springer-Verlag. 163-174 (2006).

Komeili A, Li Z, Newman DK, Jensen GJ. Magentosomes are cell memebrane invaginations organized by the actin-like protein, MamK. Science. 311: 242-245 (2006). Reprint

Komeili A, Vali H, Beveridge TJ, Newman DK. Magnetosome vesicles are present prior to magnetite formation and are activated by the MamA protein. PNAS. 101:3839-44 (2004).

Weiss B.P., Kim S.S., Kirschvink J.L., Sankaran M., Kobayashi A., Komeili A. Magnetic Tests for Magnetosome Chains in Martian Meteorite ALH84001. PNAS. 101:8281-4 (2004).

Weiss B.P., Kim S.S., Kirschvink J.L. , Sankaran M., Kobayashi A., Komeili A.. Ferromagnetic resonance and low temperature magnetic tests for biogenic magnetite. Earth and Planetary Science Letters. 224:73-89 (2004).

Komeili A, O'Shea EK. 2001. New perspectives on nuclear transport. Annu Rev Genetics. 35:341-64.

Komeili A, Wedaman KP, O'Shea EK, Powers T. 2000. Mechanism of Metabolic Control. Target of rapamycin signaling links nitrogen quality to the activity of the Rtg1 and Rtg3 transcription factors. J Cell Biol. 151:863-878.

Komeili A, O'Shea EK. 2000. Nuclear transport and transcription. Curr Opin Cell Biol. 12:355-60.

Komeili A, O'Shea EK. 1999. Roles of phosphorylation sites in regulating activity of the transcription factor Pho4. Science. 284:977-80.