ABOVE: Fluorescence microscopy image of liquid-like droplets (yellow) containing DNA (dark spots) along with poly-L-lysine and adenosine triphosphate

Cells often organize the molecules they contain by packaging them into membrane-bound compartments. But cells can also achieve interior organization using a process known as phase separation, where distinct sets of molecules end up contained in different, immiscible liquids.

To study how these membraneless organelles arise, researchers have created tiny, liquid-like droplets using DNA and poly-L-lysine, a protein made up entirely of the amino acid lysine. They found that the stability of droplets was highly dependent on the sequence of the DNA molecules they contained. For example, sequences containing only thymine (T) bases formed droplets more readily than DNA made up entirely of adenine (A).

The result reveals one way that cells might be able to fine tune phase separation and therefore intracellular organization, study coauthor Anisha Shakya of the...

A. Shakya, J.T. King, “DNA local-flexibility-dependent assembly of phase-separated liquid droplets,” Biophys J, doi:10.1016/j.bpj.2018.09.022, 2018.

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