Posts Tagged ‘division’

Cell biology: Double agents for mitochondrial division

Mitochondrial organelles — the energy powerhouses of the cell — must divide and fuse dynamically to function. It emerges that two distinct dynamin enzymes enable mitochondrial division.

What does NASA look like under Trump?

As a life-long Democrat, recently flipped to Republican who often held multiple positions on issue after issue, Donald Trump has been notoriously hard to pin down when it comes to policy plans. However, we should be able to glean some details about the president-elect’s space policy from a recent op-ed in Space News by Robert […]

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Multiple dynamin family members collaborate to drive mitochondrial division

Mitochondria cannot be generated de novo; they must grow, replicate their genome, and divide in order to be inherited to each daughter cell during mitosis. Mitochondrial division is a structural challenge that requires a massive remodelling of membrane morphology1,2,3. Although division factors differ across organisms, the need for multiple constriction steps and a dynamin-related protein (Drp1, Dnm1 in yeast) has been conserved4,5,6. In mammalian cells, mitochondrial division has been shown to proceed with at least two sequential constriction steps: (1) endoplasmic reticulum (ER) and actin collaborate to generate constrictions suitable for Drp1 assembly; (2) Drp1 further constricts membranes until fission occurs2,7,8,9. However, in vitro experiments argue that Drp1 does not have the dynamic range to complete membrane fission per se7. In contrast to Drp1, the neuronal-specific classical dynamin-1 (Dyn1) has been shown to assemble on narrower lipid profiles and facilitates spontaneous membrane fission upon GTP hydrolysis10,11. Here we discovered that the ubiquitously expressed classical dynamin-2 (Dyn2) is a fundamental component of the mitochondrial division machinery. A combination of live-cell and electron microscopy reveals that Dyn2 works in concert with Drp1 to orchestrate sequential constriction events leading up to division. Our work underscores the biophysical limitations of Drp1 and positions Dyn2, which has intrinsic membrane fission properties, at the final step of mitochondrial division.

Bacterium breaks cell biology rules, slithers away

From ScienceDaily: Bacteria are immortal as long as they keep dividing. For decades it has been assumed that a continuous, proteinaceous ring is necessary to drive the division of most microorganisms. An international team of researchers has revealed that the symbiont of the marine roundworm breaks the ring dogma and divides without. … The division […]

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