In new research, Hao Yan and his colleagues at Arizona State University's Biodesign Institute describe a pair of tweezers shrunk down to an astonishingly tiny scale. When the jaws of these tools are in the open position, the distance between the two arms is about 16 nanometers—over 30,000 times smaller than a single grain of sand.
The left panel shows tweezers in the open position, with the enzyme (green) on the upper arm and the co-factor (gold) on the lower arm. Supplying a complementary fuel strand causes the tweezers to close, producing the reaction of the enzyme-cofactor pair. (Right panel) while a set strand restores the tweezers to their open position.
Credit: The Biodesign Institute/Nature Communications
The group demonstrated that the nanotweezers, fabricated by means of the base-pairing properties of DNA, could be used to keep biological molecules spatially separated or to bring them together as chemical reactants, depending on the open or closed state of the tweezers.
In a series of experiments, regulatory enzymes—central components in a host of living processes—are tightly controlled with the tweezers, which can switch reactions on or off depending on their open or closed condition.
"The work has important implications for regulating enzymatic function and may help usher in a new generation of nanoscale diagnostic devices as well as aid in the synthesis of valuable chemicals and smart materials", said Yan.
Results of the new research appear in the current issue of the journal Nature Communications. Minghui Liu, a researcher in Biodesign's Center for Single Molecule Biophysics and the Department of Chemistry and Biochemistry at ASU is the paper's lead author. Other authors include Jinglin Fu, Yan Liu, Neal Woodbury from ASU and Christian Hejesen and Kurt Gothelf from Aarhus University, Denmark.
Enzymes are large molecules responsible for thousands of chemical interactions essential to life. A primary role for enzymes is to accelerate or catalyze myriad chemical reactions involved in processes ranging from digestion to DNA synthesis. To do this, enzymes lower the activation energy— the minimum energy needed for chemical reactions to occur—thereby speeding up the rate of such reactions. Enzymes are critical factors for health and disease, helping cells maintain their delicate homeostasis. When mutations lead to over- or under-production in certain key enzymes, severe genetic diseases—some of them, lethal—can result.
Because of the central importance of enzymes for biological systems, researchers want to gain a better understanding of how normal enzymatic reactions occur and how they may go awry. Such knowledge may encourage the development of techniques to mimic cellular processes involved in enzyme regulation.
In the current study, the authors create a nanoscale tool designed to manipulate enzymatic reactions with fine-grained control. The group dubs their device a tweezer-actuated enzyme nanoreactor.
The clever design separates an enzyme and a cofactor essential for successful reactions on separate arms of the tweezer-like instrument (See Figure 1). Enzyme function is inhibited when the tweezers are in their open position and the two molecules are held apart. Enzyme activation takes place when the tweezer prongs close, bringing enzyme and cofactor in contact. (The closing of the tweezers occurs when a specific DNA sequence is added, altering the thermodynamics of the system and causing a conformational change in the structure.)The current study explores reactions in regulatory enzymes—multitasking entities that are important for modulating biochemical pathways. Regulatory enzymes, which can catalyze reactions over and over again, accomplish their feats by binding with biomolecular cofactors. (Hormone production and regulation are just one example of regulatory enzyme activity.)
Engineering nanostructures from the bottom up, using DNA as a construction material, affords researchers exacting control over the resulting geometry. Previously, Yan has created nanostructures in two and three-dimensions, ranging from flat shapes to bowls, baskets, cages, Möbius strips and a spider-like autonomous walker.
In the tweezer design, a pair of 14 nm arms is connected at their ends by means of a 25 nucleotide single strand of DNA. This strand controls the opening and pinching of the tweezers, much the way a spring acts in a pair of gardening shears.
Two types of complementary sequence strand interact with this component, either forming a rigid DNA double helix, which supports the tweezers in their open position (set strands) or disabling the structural support and closing the tweezers, (fuel strands).
Two techniques were used to measure and analyze the resulting structures with nanoscale precision: Fluorescence Resonance Energy Transfer (FRET) and Atomic Force Microscopy (AFM). Experiments demonstrated a high yield for enzyme-bound tweezers, and successful switching between open and closed states was observed. The use of FRET allowed the process to be monitored in real time.
Lengthening the cofactor linker dangling from one of the tweezer's arms enhanced successful opening and closing of the enzyme tweezers. Analysis revealed a 5-fold increase in enzymatic activity in the closed state compared with the open state. The study also demonstrated durability in the tweezers, which were able to cycle between the open and closed positions 9 times without losing structural integrity. The process was only limited by the accumulation of set strands and fuel strands.
Future work will explore similar responsive enzyme nanodevices capable of selective chemical amplification, with potentially broad impacts for medical diagnostics. Nanoreactors may also be applied as precision biocatalysts for the production of useful chemicals and smart materials.
In addition to his position in Biodesign's Center for Single Molecule Biophysics, Hao Yan holds the Milton D. Glick Distinguished Chair in Chemistry and BiochemistryWritten by: Richard harth
Joseph Caspermeyer | EurekAlert!
Gut microbiome regulates the intestinal immune system, researchers find
19.12.2018 | Brown University
Greener days ahead for carbon fuels
19.12.2018 | DOE/Lawrence Berkeley National Laboratory
Different eras of civilization are defined by the discovery of new materials, as new materials drive new capabilities. And yet, identifying the best material...
Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.
Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
19.12.2018 | Materials Sciences
19.12.2018 | Materials Sciences
19.12.2018 | Life Sciences