DNA evolves at different rates, depending on the structure of the chromosomes

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The structure of how DNA is stored in archaea makes a significant difference in how quickly it evolves, according to a new study by researchers at Indiana University.

The study, led by molecular biologist Stephen Bell, professor emeritus and chair of the Department of Molecular and Cellular Biochemistry at Indiana University (IU) Bloomington’s College of Arts and Sciences, was recently published in Natural microbiology. His findings could have an impact on research into the treatment of genetic diseases such as cancer.

“The most exciting thing we’ve revealed is the idea that the shape of a DNA molecule can affect its ability to change,” Bell said. “At the beginning of the 20th century, modernist architecture had the idea that the form of a building should follow its function. But what we see in these organisms is that over time form actually affects evolution. The way DNA is structured can change it, creating an evolutionary feedback loop.

Archaea, single-celled microorganisms discovered in the 1970s, are one of three domains of life on Earth, which scientists use to classify all life forms. The other two areas are bacteria and eukaryotes, which include mammals and humans. Archaea is perhaps the oldest realm of the three.

“You can think of archaea as molecular fossils,” Bell said. “Studying them is like stepping into a time machine and looking back around 2 billion years.”

Previous research by Bell and his IU collaborators, Rachel Samson, assistant researcher in the Department of Molecular and Cellular Biochemistry; and Naomichi Takemata, a postdoctoral researcher in Bell’s lab, found that some species of archaea organize their chromosomes, which store DNA, into two compartments.

For this new study, Catherine Badel, a postdoctoral researcher at the Bell laboratory, Samson and Bell measured chromosome mutation rates in 11 species of a certain genus of archaea. Their analysis demonstrated that DNA in one compartment, where it was more compactly stored, changed at a much faster rate than the other compartment.

The finding is important, Bell said, because understanding the form and function of DNA can help researchers better understand all life forms, including humans. This knowledge could one day help researchers improve treatments for genetic diseases or other genetic errors.

“We have to understand how something works before we can figure out how to fix it when something is wrong,” he said.

This research builds on previous work by Bell and co-workers, who in a previous study found similarities between human and archaeal chromosomes.


Key similarities discovered between human and archaeal chromosomes


More information:

Catherine Badel et al, Chromosome organization affects genome evolution in Sulfolobus archaea, Natural microbiology (2022). DOI: 10.1038/s41564-022-01127-7

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Ida M. Morgan