New insights into DNA 'melting' reveal chink in bacteria's armour

June 22, 2018 by Kate Wighton, Imperial College London
Proteins interacting with DNA. Credit: Imperial College London

Scientists have shed light on DNA 'melting' – a crucial process fundamental to all life.

The researchers, from Imperial College London, who used bacteria in their experiments, say these findings may provide new insights into eradicating harmful bugs.

DNA encodes information to make proteins, which are key to all processes in . The DNA molecule is composed of two complementary strands, which are normally wrapped around each other in a helical structure.

When a cell wants to make proteins, the strands need to be pulled apart or 'melted' first, before a fundamental cellular process called transcription takes place.

Because transcription also takes place in human cells, the new findings may provide insights for conditions such as cancer and other diseases.

But although this DNA melting process is fundamental to life, scientists are still in the dark about the intricate details of how the cell's machinery captures and reads the DNA.

In the new research, published in Molecular Cell, the team used an extremely powerful technique called cryo-electron microscopy to physically see how the DNA melting happens in detail.

The experiments focused on a molecule called RNA , that captures and pulls apart the DNA, before reading the sequence in the melted out DNA strand to make a molecule called RNA.

This is then used as a template to make proteins. The findings revealed that the RNA polymerase molecule changes shape in a dramatic fashion when it locks onto DNA.

This shape-shifting allows it to capture and 'melt' the DNA at the same time.

Previously, researchers were unclear if RNA polymerase captured the DNA before unwinding the strands, or if DNA is melted out first before fully captured by the RNA polymerase. Now their new finds reveal these two events are integrated processes.

Professor Xiaodong Zhang, lead author of the study from the Department of Medicine, said these insights may help scientists design more effective antibiotics.

"How DNA melts is a fundamental part to all life – bacterial and human. Now that we know how RNA polymerase changes it shape to melt the DNA, this opens avenues for interfering with this pathway – and stopping bacterial growth."

And because this production system is the same in humans, these findings may also provide clues into disease, explained co-author Professor Martin Buck, from the Department of Life Sciences.

"Protein production can become dysregulated in diseases such as cancer, and these findings could give us greater understanding of how this can happen. The results may also have implications for gene-editing techniques such as CRISPR, which allows scientists to insert or remove genes—as these require targeted gene melting."

"Structures of bacterial RNA Polymerase complexes reveal mechanism of DNA loading and transcription initiation" by R.Glyde et al. is published in Molecular Cell.

Explore further: First-ever look at DNA opening reveals initial stage of reading the genetic code

More information: "Structures of bacterial RNA Polymerase complexes reveal mechanism of DNA loading and transcription initiation," Molecular Cell

Related Stories

New function in gene-regulatory protein discovered

October 20, 2017

Researchers at Umeå and Stockholm universities in Sweden and Johns Hopkins University School of Medicine in the U.S. have published a new study in the journal Molecular Cell. They show how the protein CBP affects the expression ...

Recommended for you

Can China keep it's climate promises?

March 26, 2019

China can easily meet its Paris climate pledge to peak its greenhouse gas emissions by 2030, but sourcing 20 percent of its energy needs from renewables and nuclear power by that date may be considerably harder, researchers ...

What happened before the Big Bang?

March 26, 2019

A team of scientists has proposed a powerful new test for inflation, the theory that the universe dramatically expanded in size in a fleeting fraction of a second right after the Big Bang. Their goal is to give insight into ...

Cellular microRNA detection with miRacles

March 26, 2019

MicroRNAs (miRNAs) are short noncoding regulatory RNAs that can repress gene expression post-transcriptionally and are therefore increasingly used as biomarkers of disease. Detecting miRNAs can be arduous and expensive as ...

In the Tree of Life, youth has its advantages

March 26, 2019

It's a question that has captivated naturalists for centuries: Why have some groups of organisms enjoyed incredibly diversity—like fish, birds, insects—while others have contained only a few species—like humans.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.