CELL BIOLOGY: Full to Bursting

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Science  11 May 2007:
Vol. 316, Issue 5826, pp. 801b
DOI: 10.1126/science.316.5826.801b

Peroxisomes are membrane-bounded intracellular organelles that carry out important oxidative reactions in lipid metabolism. In order to adequately supply daughter cells, peroxisomes must multiply and divide throughout the cell cycle. Guo et al. have examined the maintenance and division of peroxisomes in yeast—specifically, how peroxisomal membrane lipids and proteins are dynamically and spatially regulated during the cell cycle. They find that as peroxisomes mature, they accumulate larger quantities of the enzymes involved in lipid metabolism. One of these, acyl-CoA oxidase, is primarily localized to the matrix (the interior of the peroxisome) in immature organelles but is partly found in association with the inner surface of the peroxisomal membrane in mature organelles. Once at the membrane, acyl- CoA oxidase binds to the protein Pex16p; this interaction activates the transformation of endogenous lipids into components that induce bending of the outer leaflet of the membrane, which, in turn, activates peroxisomal membrane proteins that mediate division of the organelle. Thus, peroxisomes have an internal sensing mechanism that triggers their own multiplication as they grow. — SMH

J. Cell Biol. 177, 289 (2007).

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