Cell Biology

How Different Are We?

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Science  27 Jun 2003:
Vol. 300, Issue 5628, pp. 2005
DOI: 10.1126/science.300.5628.2005c

Subcellular organelles—membrane-bound intracellular compartments—have been thought to be an invention of eukaryotes. Now Seufferheld et al. challenge this dogma by the discovery of subcellular organelles within bacteria. Within the cytoplasm of Agrobacterium tumefaciens the so-called volutin granules displayed all the hallmarks of acidocalcisomes, an organelle found in unicellular eukaryotes. The granules were surrounded by a membrane and contained large concentrations of P, Mg, K, and Ca. The membrane, which had a distinct composition from the plasma membrane, contained a proton pump. The lumen of the granules was acidic and could accumulate externally added calcium. Thus, this organelle seems to be of very ancient origin, having appeared before the separation of prokaryotes and eukaryotes.—SMH

J. Biol. Chem. 10.1074/jbc. M304548200 (2003).

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