Clustering of large complexes gives smaller ones more room to move.

COOK/BIOPHYSICAL SOCIETY

The tendency of large complexes to congregate drives the organization of the genome and other cellular structures, according to Peter Cook (University of Oxford, UK).

In a crowded, enclosed space (such as the cell), the aggregation of two large spheres increases the system's entropy by giving lots of little molecules more room to move around. In physics, this effect is known as depletion attraction. Using mathematical modeling, Cook and colleagues found that this attraction explains the looping of DNA found naturally in cells.

The model is based on transcription and replication complexes that are spaced along DNA like beads on a string. Measurements of the attraction between the “beads” suggest that the entropy gained by their clustering is enough to cover the energy costs of looping the DNA string between them.

In...

The Rockefeller University Press
2006
The Rockefeller University Press
2006
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