Laser spotlight reveals machine 'climbing' DNA

Oct 26, 2012

(Phys.org)—New imaging technology has revealed how the molecular machines that remodel genetic material inside cells 'grab onto' DNA like a rock climber looking for a handhold.

The experiments, reported in this week's Science, use to generate very bright patches close to single cells. When coupled with fluorescent tags this 'spotlight' makes it possible to image the inner workings of cells fast enough to see how the inside change size, shape, and composition in the presence of DNA.

The Oxford team built their own technology for the study, which is a collaboration between the research groups of Mark Leake in Oxford University's Department of Physics and David Sherratt in Oxford University's Department of Biochemistry.

The molecular machines in question are called Structural Maintenance of Chromosome (SMC) complexes: they remodel the inside every living cell and work along similar principles to a large family of molecules that act as very small motors performing functions as diverse as trafficking vital material inside cells to allowing muscles to contract.

The researchers studied a particular SMC, MukBEF (which is made from several different ), inside the bacterium E.coli. David Sheratt and his team found a way to fuse 'fluorescent proteins' directly to the DNA coding for MukBEF, effectively creating a single dye tag for each component of these machines.

Up until now conventional techniques of biological physics or biochemistry have not been sufficiently fast or precise to monitor such tiny machines inside living cells at the level of single molecules.

'Each machine functions in much the same way as rock-climber clinging to a cliff face,' says Mark Leake of Oxford University's Department of Physics, 'it has one end anchored to a portion of while the other end opens and closes randomly by using chemical energy stored in a ubiquitous bio-molecule called adenosine triphosphate, or 'ATP': the universal molecular fuel for all living cells.

'This opening and closing action of the machine is essentially a process of mechanical 'grabbing', in which it attempts to seize more free DNA, like the rock-climber searching for a new handhold.'

It is hoped that pioneering biophysics experiments such as this will give fresh insights into the complex processes which are vital to life, and pave the way for a whole new approach to biomedical research at the very tiny length scale for understanding the causes of many diseases in humans, and how to devise new strategies to combat them.

Explore further: Cell resiliency surprises scientists

More information: Science 26 October 2012: Vol. 338 no. 6106 pp. 528-531 DOI: 10.1126/science.1227126

Related Stories

DNA cages 'can survive inside living cells'

Jul 04, 2011

(PhysOrg.com) -- Scientists at Oxford University have shown for the first time that molecular cages made from DNA can enter and survive inside living cells.

Proteins shine a brighter light on cellular processes

Mar 20, 2012

Scientists have designed a molecule which, in living cells, emits turquoise light three times brighter than possible until recently. This improves the sensitivity of cellular imaging, a technique where biological ...

Scientists capture single cancer molecules at work

Dec 08, 2011

Researchers have revealed how a molecule called telomerase contributes to the control of the integrity of our genetic code, and when it is involved in the deregulation of the code, its important role in the development of ...

Recommended for you

Ocean microbes display remarkable genetic diversity

12 hours ago

The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacteria species essential to the marine ecosystem. An estimated billion billion billion of the single-cell creatures live i ...

Cell resiliency surprises scientists

13 hours ago

New research shows that cells are more resilient in taking care of their DNA than scientists originally thought. Even when missing critical components, cells can adapt and make copies of their DNA in an alternative ...

Cell division speed influences gene architecture

Apr 23, 2014

Speed-reading is a technique used to read quickly. It involves visual searching for clues to meaning and skipping non-essential words and/ or sentences. Similarly to humans, biological systems are sometimes ...

User comments : 0

More news stories

Ocean microbes display remarkable genetic diversity

The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacteria species essential to the marine ecosystem. An estimated billion billion billion of the single-cell creatures live i ...

Genetic code of the deadly tsetse fly unraveled

Mining the genome of the disease-transmitting tsetse fly, researchers have revealed the genetic adaptions that allow it to have such unique biology and transmit disease to both humans and animals.

Cell resiliency surprises scientists

New research shows that cells are more resilient in taking care of their DNA than scientists originally thought. Even when missing critical components, cells can adapt and make copies of their DNA in an alternative ...