Phages are viruses that attack bacteria by injecting their DNA, then usurping bacterial machinery to reproduce. Eventually, they make so many copies of themselves that the bacteria burst. By looking at this process in a unique type of virus called a jumbo phage, scientists hope to learn how to make new antibiotics that can address the growing crisis of resistance.

The jumbo phage has more than four times the DNA of an average phage. It uses this genetic material to create a restricted space inside bacteria where it can copy its DNA while surrounded by a protective shield made of protein.

Researchers at UC San Francisco have discovered that the shield works via a set of “secret handshakes.” They allow only a specific set of useful proteins to pass through.

DNA (deoxyribonucleic acid), the molecular “blueprint” carrying the genetic instructions that influence the growth, development, reproduction and predispositions of individual humans, can undergo different types of mechanical stress inside cells. For instance, it can be twisted or stretched, impacting its overall structure and dynamics.

Researchers at the University of York recently explored how DNA behaves under torsion and tension using molecular dynamics simulations. These atomic-scale simulations yielded interesting new findings, which were published in a paper in Physical Review Letters.

“I have always been interested in studying how DNA behaves inside the cell,” Dr. Agnes Noy, senior author of the paper, told Phys.org. “We are used to thinking of DNA as a relaxed ‘perfect’ double helix, but the reality is far from that. Inside cells, DNA is under/overtwisted, resulting in the formation of ‘supercoiled’ loops, resembling what can happen to long cords or garden hoses in our homes.”