Built to Fold


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Embedded in the genome is yet another code made up of two-letter signals that repeat themselves periodically.
Discovered in 2006 by Dr. Eran Segal of the Computer Science and Applied Mathematics Department and his group, this code appears at intervals of 10 base pairs (the “letters” of the genetic code) in certain DNA sequences. It facilitates the bending of segments of about 150 base pairs into protein-DNA complexes called nucleosomes – neat, spherical beads strung on the DNA strand.
Two new studies by his group, which appeared recently in Nature and Nature Genetics, provide evidence that this code is universal, from yeast to humans, and that it helps to shape those organisms and streamline the process of gene expression. The group, including research students Noam Kaplan and Yair Field, along with Yaniv Lubling, carried out this research in collaboration with the groups of Jonathan Widom at Northwestern University in Evanston, Illinois, Jason Lieb at the University of North Carolina in Chapel Hill, North Carolina, and Tim Hughes at the University of Toronto. “In the 2006 study, we worked with several hundred DNA sequences. Today, with new advances in technology, we can test something like 10 million,” says Segal.
In the second study, Segal and his team revisited previous Institute research from the group of Prof. Naama Barkai of the Molecular Genetics Department. They discovered that differences in gene expression are tied to changes in the placement of nucleosomes, which, in turn, might constitute a previously unidentified genetic mechanism for achieving change across evolution.
Dr. Eran Segal’s research is supported by the Chais Family Fellows Program for New Scientists; the Hana and Julius Rosen Fund; and the Cecil and Hilda Lewis Charitable Trust.