A Rensselaer researcher has developed a new tool to help unravel the function of an elusive DNA structure. The findings, which were presented at the 230th national meeting of the American Chemical Society (ACS) in Washington, D.C., could lead to a better understanding of diseases such as cancer and diabetes.

Image of Standard DNA

The standard version of the human genome is a double-stranded helix of complementary bases: adenine binds to thymine and cytosine binds to guanine. “Our focus is on a different type of DNA structure, the ‘G-quartet,’ that arises from hydrogen bonds between guanines only,” says Linda McGown, professor and chair of the Department of Chemistry and Chemical Biology at Rensselaer.

Scientists have long speculated about the existence of these G-quartets, as well as the role they might play in the human body, but direct evidence has remained elusive. To help answer these questions, McGown and her students at Rensselaer and Duke University have been examining this unusual structure, which is a rectangular array of four guanines, each hydrogen-bonded to its two nearest neighbors.

McGown has developed a strategy to compare the way proteins bind to G-quartets in different types of cells. “This is essentially a fishing experiment,” she says. Using hooks made of sequences from the DNA genome, she hopes to catch proteins that might bind to G-quartets.

For example, McGown recently discovered that insulin binds to a G-quartet formed by a sequence that occurs in the insulin promoter gene. “The possibility that insulin may participate in its own regulation is intriguing, and adds to the growing evidence relating G-quartet formation and diabetes,” she says.

She plans to apply her technique to G-quartet-forming sequences that occur in other regions of human chromosomes and have been implicated in cancer, aging, and genetic diseases.  Her goal is to increase understanding of the role of G-quartets in health and disease, leading to the identification of new biomarkers and medical therapies.

McGown was among 18 Rensselaer researchers presenting at the ACS meeting in Washington, along with Rensselaer President Shirley Ann Jackson, who spoke at a special event celebrating the 10th anniversary of the ACS Scholars Program. Her talk focused on the urgent need to build the next generation of scientists, which she asserts requires fostering a national plan and a national will to succeed.

Read the press release.

Published September 6, 2005