Professor Profile: The DNA Stretcher

DNA is in all of us. It’s what we’re made of. Every kind of science is being applied to better understand the material of life. Physicists, for example, are trying to stretch and prod DNA to see how it responds.

We wondered why, so we asked Professor Mark Williams who teaches biological physics at Northeastern and has been studying DNA stretching for several years.
What is DNA Stretching?
It takes really small “fingers” to stretch DNA. These nanofingers have to be specially made and calibrated.

What do you learn from these measurements?
To explain it simply, DNA is a double-stranded helix that is held together by base pairs. These base pairs create a genetic code.

“All living things have this DNA that stores information, and they also have to read that information somehow when they replicate and when they want to make proteins,” explains Williams.

When you pull DNA molecules, the DNA can be opened up, which exposes the base pairs. This is where Williams shines. “We use this method to study various proteins in the cell that interact with DNA. The idea is to try and understand how proteins interact with DNA by mimicking the process of opening the DNA and seeing how things affect that.”

DNA Stretching and HIV
There are several reasons why scientists would stretch DNA.

Williams has spent years using DNA stretching to study HIV replication and the proteins involved with the replication. “The idea is to try and understand how these proteins allow HIV to replicate,” Williams explains. “Hopefully that understanding will help contribute to the development of drugs that target proteins associated with HIV.”
Williams has a lab of graduate and post-doc students who help him with his research here at Northeastern University.

Williams has received two grants from the National Institute of Health—one of the major federal funding organizations—to continue his work with DNA stretching and HIV replication.

His most recent grant was renewed in May 2010.
National Recognition
Williams has received national recognition for his work.

Just recently, he was quoted in three separate articles focused on the science of DNA stretching.

These pieces were published in Chemical & Engineering News, New Scientist and Science News. “It’s really great,” Williams says. “It makes me realize that people know who I am and that I’m an expert in this field… It’s hard in science to know if you are really well-known.”

*In 2010, Williams was promoted to full professor at Northeastern University. He recently edited a book called “Biophysics of DNA Protein Interactions: From Single Molecules to Biological Systems” and was just appointed to the Nucleic Acids Research editorial board.

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