Biologists have revealed the mystery of DNA folding during chromosome binding

Biologists at Johns Hopkins University have found an important clue to solve a long-standing unresolved problem – how long strands of DNA “shrink” when homologous chromosomes in the cell nucleus form a tight connection. A research article is published in the journal Developmental Cell.

One of the options for how the chromosomes “contact” with each other looks like this: they come together, just like buttons fastened on a shirt. If the chromosomes are properly “buttoned up,” the eyes and limbs of the flies form as they should. But incorrectly fastened chromosomes lead to vision problems, to legs on the head instead of antennas and other defects.

Human DNA is harder than a fly, but chromosomes “fasten” the same way in special cases, and knowing how this process works can help explain gene expression, in particular how genetic abnormalities can lead to disease.

“The meter (the total length of the strands, approx. Indicator.Ru) of the DNA in the human body must be folded into a very compact form and do it in the same way every time – and we hardly know how it works,” the lead author of the work notes , graduate student at Johns Hopkins University Kyle Witz. “Fastening is only one way of contacting chromosomes, and our work is a very important first step towards a better understanding of this process.”

Fastening is a specialized way that some human chromosomes connect during development. But in flies, this process is easy, which makes them an ideal model for study. A team of scientists found that chromosomes in some parts of the body of a fly are better connected with each other than in others.

Scientists have processed the chromosomes of fruit fly larvae so that they glow. In this way, scientists were able to see if the process was going on correctly or not. Scientists observed it inside the cells of the eye of fruit flies. In case of improper “fastening”, the experimental subjects would have problems with color perception and, in general, with eyesight. But it was found that the chromosomes in these cells are connected correctly. But in the antennas of flies this connection took place in a different way, and the wrong “fastening” led to amazing mutations, namely to the legs growing on the head instead of antennas.

“Our work adds another piece to the puzzle of understanding how DNA is put together to make sure genes work properly,” said Robert Johnston, research director at Johns Hopkins University.