Thanks to this technology, it has now been proven that the seemingly chaotic cluster of bacterial DNA is in fact organized and can function dynamically. Moreover, the H-NS protein is a potential target for developing medication to treat bacterial infections. The research findings will be published in the scientific journal Nature on November 16, 2006.
Unlike cells in the human body, bacteria do not have a nucleus. These micro-organisms are much less complex than our human body cells, but this, rather surprisingly, makes it more difficult to determine how the DNA in a bacterial cell is organized. Prior to the use of the newly developed optical tweezers instrument, it was very difficult to study the spatial organization of bacterial DNA.
In human and animal cells, DNA-strands are coiled up inside chromosomes and extremely well organized. The bacterial chromosome is much more dynamically organized by a small group of proteins that non-specifically bind the DNA. Consequently, these proteins have more, and more general, functions. The DNA appears to be unorganized, like a ball of noodles in the cell – or so it seemed at least.
For cell division or DNA repair, the bacterium must duplicate its DNA, and this cannot be done without choreographed order. DNA duplication is the result of (among other factors) the action of DNA binding motor proteins: they slide along the DNA and replicate every nucleotide in the DNA-sequence. It was already known that certain proteins prevented the DNA from becoming entangled; but what was unknown is how it was then possible for a motor protein to slide along the DNA-strands. This mystery has now been solved.
Gijs Wuite, Remus Dame and Maarten Noom, the authors of the article to be published in Nature, began by demonstrating that a specific protein (namely, histone-like nucleoid structuring protein, H-NS) bridges two DNA strands. H-NS is a small protein that has on both its ends a small, ball-like element that can attach to DNA, probably fitting in the small cavities along the DNA’s spiral staircase-like structure. Remus Dame: “It’s great that in our measurements the helical shape of the DNA emerges. But what is much more important is that we were able to measure the strength with which the H-NS is bound to the DNA.” It is a weak bond: each H-NS arm is loosely bound to a DNA-helix.
Moreover this bond is unstable: over a certain period of time, the arm of the H-NS comes loose, in order to then reattach itself to the DNA. Because there is a lot of H-NS protein between the two parallel DNA-helices, the overall bridging activity is unhindered if each protein occasionally let’s go and then reattaches itself. Gijs Wuite: “And this precisely explains why motor proteins are unhindered by H-NS when they move along the DNA: the force these proteins exert is greater, and H-NS simply allows them to pass. This has never before been demonstrated.”
Department Science Communication | alfa
Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials
17.01.2018 | Universität des Saarlandes
Black hole spin cranks-up radio volume
15.01.2018 | National Institutes of Natural Sciences
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
17.01.2018 | Ecology, The Environment and Conservation
17.01.2018 | Physics and Astronomy
17.01.2018 | Awards Funding