ABOVE: Chromatin “tree” structure

Researchers have uncovered how chromatin, a mix of DNA and proteins that makes up chromosomes, folds at the molecular level. Chromatin is composed of branches that bend back on themselves and are spaced along a backbone, giving the structure gaps that allow it to be tightly packed, according to a study published in Science Advances last Friday (January 10).

Simulated 3-D structure of chromatin showing its porosity (white spaces)

A team co-led by Igal Szleifer and Vadim Backman, both biomedical engineers at Northwestern University, used mathematical modeling and microscopy to understand the 3-D structure of the genome of human cells at the nanoscale. They found that chromatin consists of tree-like domains of varying sizes, forming a “3D forest,” the study authors write. The complexity of this configuration suggests that chromatin has more organization and structural hierarchy than previously thought, which...

“If genes are the hardware, chromatin is the software,” says Backman in a press release. “If the structure of chromatin changes, it can alter the processing of the information stored in the genome, but it does not alter the genes themselves. Understanding chromatin folding holds the key to understanding how cells differentiate and how cancer happens.”

In this 3-D chromatin model, red represents the smallest loops of branched chromatin and green represents the largest. 

K. Huang et al., “Physical and data structure of 3D genome,” Sci Adv, doi:10.1126/sciadv.aay4055, 2020.

Emily Makowski is an intern at The Scientist. Email her at emakowski@the-scientist.com.

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