Small, structured nucleic acid strands designed to interact with specific target molecules, known as aptamers, are particularly interesting to scientists as therapeutics against viruses and blood clotting disorders. Aptamers that bind strongly to target enzymes or proteins can prevent their activity, thereby regulating the biological process they control.
Aptamers frequently contain stacks of hydrogen-bonded guanine-rich sequences, called quadruplexes, which enable effective binding to targets. When these structures are disrupted or destroyed—perhaps through poor replication—the aptamer can no longer bind. Interestingly, the reversible formation and disruption of these quadruplexes have the potential to be controlled using external stimuli, leading to a switching on and off of the aptamer's binding. Using this idea, Shinzi Ogasawara and Mizuo Maeda at the RIKEN Advanced Science Institute in Wako, have developed a light-controlled switch to control quadruplex formation in an aptamer that binds specifically to thrombin1, the protein in blood that control blood coagulation.
The researchers developed a range of modified aptamers that contained various numbers of potential quadruplex structural units. Using light they were able to switch and select between a stable quadruplex and a non-structured state. Using light to control a switch allows accurate and easy control of the location, dosage, and timing. They then screened their variant aptamers to determine the best number and positions of the structural units to give effective regulation.
More specifically, Ogasawara and Maeda were able to control the switching behavior using light of specific wavelengths. In solution, they found that when the quadruplex is present, the aptamer binds strongly to thrombin. When the sample was irradiated at 410 nanometers, the double bonds within the complex changed from a so-called trans configuration to a cis configuration that disrupted the quadruplex and suppressed binding of the aptamer. Irradiation at 310 nanometers, however, changed the bonds back into the trans form, allowing the quadruplex to re-form and bind once again.
Ogasawara and Maeda realized that the release-and-bind steps could be repeated over two cycles. First, they irradiated a reaction sample at 410 nanometers for 5 minutes and then at 310 nanometers for 2 minutes. After repeating the irradiation cycle, they found that the switch was completely reversible, and they detected no side reactions, thus demonstrating its potential in living cells.
Ogasawara and Maeda now plan to apply this technique to investigate other important biological events involving quadruplexes, such as gene expression and the construction of molecular machines.
The corresponding author for this highlight is based at the Bioengineering Laboratory, RIKEN Advanced Science Institute
Saeko Okada | Research asia research news
Transport of molecular motors into cilia
28.03.2017 | Aarhus University
Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
29.03.2017 | Materials Sciences
29.03.2017 | Physics and Astronomy
29.03.2017 | Earth Sciences