OxFord University: Flesh-eating bacteria inspire superglue

A bio-inspired superglue has been developed by Oxford University researchers that can’t be matched for sticking molecules together and not letting go.

It could prove to be a very useful addition to any toolbox for biotechnology or nanotechnology. You could use the glue to grab hold of proteins or stick them immovably to surfaces. You could even use it to assemble proteins and enzymes to build new structures on the nanometre scale.

‘We’re very interested in creating protein assemblies. We want to be able to treat proteins like Lego,’ explains Dr Mark Howarth, who with his graduate student Bijan Zakeri at the Department of Biochemistry developed the superglue. ‘But previously we’ve been limited to ill-controlled processes or have had to build using weak biological interactions.’

The Oxford biochemists came up with their new super-strength molecular glue by engineering an unusual protein from a type of bacteria that can cause life-threatening disease.

While many people carry Streptococcus pyogenes in their throat without any problems, the bacteria can cause infections. Some are mild, like impetigo in infants or a sore throat, but some can kill, like toxic shock syndrome or flesh-eating disease.

What attracted the biochemists’ interest was a specific protein which the bacteria use to bind and invade human cells.

‘The protein is special because it naturally reacts with itself and forms a lock,’ says Mark.

All proteins consist of amino acids linked together into long chains by strong covalent bonds. The long chains are folded and looped up into three-dimensional structures held together by weaker links and associations.

The protein FbaB from S. pyogenes has a 3D structure that is stabilised by another covalent bond. This strong chemical bond forms in an instant and binds the loops of the amino acid chain together with exceptional strength.

Mark and his colleagues reckoned with a bit of engineering they could split the protein around this extra covalent bond. Then, when the two parts were brought together again, they might dock and form this strong bond once more.

The two parts would be locked together immovably – stapling together anything else attached to their tails.That is what the researchers have now demonstrated in this week’s PNAS.

They’ve nicknamed the larger fragment which formed the bulk of the original protein ‘SpyCatcher’. Once SpyCatcher gets hold of the shorter protein segment, ‘SpyTag’, it never lets go.

At least, the researchers with their collaborators at the University of Miami tried to measure the force needed to pull apart SpyTag from SpyCatcher using an atomic force microscope.

But when they pulled on each end, the chemical links holding the proteins to the apparatus broke first. Boiling in detergent won’t separate the protein fragments either.

‘Our system forms rapid covalent bonds with high efficiency and high stability,’ says Mark.

When SpyCatcher and SpyTag are brought together, they bond in minutes with high yield. It doesn’t matter whether it is in acidic or neutral conditions, or whether it is 4°C or 37°C.

They will stick together in test tube reactions or inside cells. And importantly, they don’t stick to other things – there’s no equivalent of getting your fingers stuck to the Airfix model you’re building.

Mark explains that there isn’t really any equivalent way to bind biomolecules together. There are chemical reactions that can join two proteins together covalently but often only small proportions react, they take a long time, or they require UV light, toxic catalysts or reaction conditions that could damage living cells.

The ability to attach SpyCatcher and SpyTag onto other molecules you want to glue together could have many applications. For example, sticking all the enzymes involved in a chemical process into a small factory could speed reactions and increase yields.

Or you might want to bring all the elements together that plants use to turn sunlight into energy with only water as a waste product. Scientists have long wanted to come up with ways of achieving photosynthesis artificially for useable green energy.

But the first uses of the molecular superglue may well be in the research lab, grabbing hold of structures within biological cells. That way you could resist the forces generated by important motors, machines and transporters inside the cell.

Mark and his team are now working on developing the molecular superglue technology through Isis Innovation, the University of Oxford’s technology transfer company.

Spitzer & Chandra X/Ray Image: molecular cloud

This composite image, created using data from the Chandra X-ray Observatory and the Spitzer Space Telescope, shows the molecular cloud Cepheus B, located in our galaxy about 2,400 light years from the Earth.

A molecular cloud is a region containing cool interstellar gas and dust left over from the formation of the galaxy and mostly contains molecular hydrogen. #

The Spitzer data, in red, green and blue shows the molecular cloud (in the bottom part of the image) plus young stars in and around Cepheus B, and the Chandra data in violet shows the young stars in the field.

The Chandra observations allowed the astronomers to pick out young stars within and near Cepheus B, identified by their strong X-ray emission.

The Spitzer data showed whether the young stars have a so-called "protoplanetary" disk around them. Such disks only exist in very young systems where planets are still forming, so their presence is an indication of the age of a star system.

These data provide an excellent opportunity to test a model for how stars form. The new study suggests that star formation in Cepheus B is mainly triggered by radiation from one bright, massive star (HD 217086) outside the molecular cloud.

According to the particular model of triggered star formation that was tested, called the radiation-driven implosion (RDI) model, radiation from this massive star drives a compression wave into the cloud triggering star formation in the interior, while evaporating the cloud's outer layers.

Different types of triggered star formation have been observed in other environments. For example, the formation of our solar system was thought to have been triggered by a supernova explosion.

In the star-forming region W5, a "collect-and-collapse" mechanism is thought to apply, where shock fronts generated by massive stars sweep up material as they progress outwards.

Eventually the accumulated gas becomes dense enough to collapse and form hundreds of stars. The RDI mechanism is also thought to be responsible for the formation of dozens of stars in W5.

The main cause of star formation that does not involve triggering is where a cloud of gas cools, gravity gets the upper hand, and the cloud falls in on itself.

Image Credit: X-ray: NASA/CXC/PSU/K. Getman et al.; IRL NASA/JPL-Caltech/CfA/J. Wang et al.

World's smallest electric motor made from single molecule

Chemists at Tufts University have developed the world's first single molecule electric motor, which may potentially create a new class of devices that could be used in applications ranging from medicine to engineering.

The molecular motor was powered by electricity from a state of the art, low-temperature scanning tunneling microscope.

This microscope sent an electrical current through the molecule, directing the molecule to rotate in one direction or another.

The molecule had a sulphur base (yellow); when placed on a conductive slab of copper (orange), it became anchored to the surface.

The sulphur-containing molecule had carbon and hydrogen atoms radiating off to form what looks like two arms (gray); these carbon chains were free to rotate around the central sulphur-copper bond.

The researchers found that reducing the temperature of the molecule to five Kelvin (K), or about minus 450 degrees Fahrenheit (ºF), enabled them to precisely impact the direction and rotational speed of the molecular motor

The Tufts team plans to submit this miniature electric motor to the Guinness World Records. The research was published online Sept. 4 in Nature Nanotechnology.

Credit: Heather L. Tierney, Colin J. Murphy, April D. Jewell, Ashleigh E. Baber, Erin V. Iski, Harout Y. Khodaverdian, Allister F. McGuire, Nikolai Klebanov and E. Charles H. Sykes.

One box of Girl Scout cookies worth $15 billion - YouTube

In a paper published in the journal ACS Nano, scientists  described how graphene, a single-atom-thick sheet of carbon, can be made from just about any carbon source, including food, insects, and waste.

Read the original study: DOI: 10.1021/nn202625c

“I said we could grow it from any carbon source, for example, a Girl Scout cookie, because Girl Scout cookies were being served at the time,” says James Tour, professor of mechanical engineering and materials science and of computer science at Rice University. “So one of the people in the room said, ‘Yes, please do it. … Let’s see that happen.’”

A sheet of graphene is so thin that one sheet made from one box of shortbread cookies would cover nearly three football fields.

The scientists say the experiment is a whimsical way to make a serious point: that graphene, touted as a miracle material for its toughness and conductivity since its discovery in 2004, can be drawn from many sources.

Tour and graduate students Gedeng Ruan, lead author of the paper, and Zhengzong Sun, also tested other materials, including chocolate, grass, polystyrene plastic, insects (a cockroach leg) and even dog faeces.

In every case, the researchers were able to make high-quality graphene via carbon deposition on copper foil.

In this process, the graphene forms on the opposite side of the foil as solid carbon sources decompose; the other residues are left on the original side. Typically, this happens in about 15 minutes in a furnace flowing with argon and hydrogen gas and turned up to 1,050 degrees Celsius.

Tour expects the cost of graphene to drop quickly as commercial interests develop methods to manufacture it in bulk. In earlier research, Tour  described a long-sought way to make graphene-based transparent electrodes by combining graphene with a fine aluminum mesh.

The material could possibly replace expensive indium tin oxide as a basic element in flat-panel and touch-screen displays, solar cells, and LED lighting.

The new findings have “a lot to do with current research topics in academia and in industry,” Tour says. “Carbon—or any element—in one form can be inexpensive and in another form can be very expensive.”

Diamonds are a good example., he says. “You could probably get a very large diamond out of a box of Girl Scout cookies.”

Sandia National Laboratory, the Air Force Office of Scientific Research, and the Office of Naval Research MURI program funded the research.

More news from Rice University: www.media.rice.edu/media/

Discoverers of graphene bring graphene-based electronics a step closer

The researchers who unveiled graphene in 2004 and who were awarded the Nobel Prize in 2010 for “groundbreaking experiments regarding the two-dimensional material" have led new research that reveals more about the electronic properties of the wonder material.

The team says their findings promise to accelerate research looking at ways to build graphene-based devices such as touch-screens, ultrafast transistors and photodetectors, and will potentially open up countless more electronic opportunities.

Discoverers of graphene bring graphene-based electronics a step closer - Image 1 of 1

Chaos Theory Moves on: What about Entanglement?

At the level of atoms, our definition of chaos has run into a problem.

Chaos is usually defined by a system’s movement: Set a pendulum swinging, track exactly where it goes, and its motion will reveal whether it is chaotic. Atoms, however, are governed by the uncertainty principle, which means that their location cannot be known precisely. What’s more, the laws of quantum mechanics say that hypersensitivity to initial conditions, which is considered the primary characteristic of a chaotic system, is physically impossible for atoms—at least in the way it’s understood at the classical level.

This presents a serious quandary because quantum mechanics is considered the most basic set of universal laws. Chaos must have some connection with the quantum level, but how it manifests itself, or how to quantify it, has thus far eluded physicists. Work published recently in Nature helps shed light on this problem as researchers working with cooled atoms searched for what they call signatures of chaos.

If such hypersensitivity to initial conditions cannot happen in a quantum system, other red flags of classical chaos might still be detectable. This could indicate that chaos in some form could exist at the level of atoms, or, at the very least, would imply a connection between quantum events and classical chaos. “Though you will never be able to find hypersensitivity to initial conditions in the quantum system, you are able to tell if the outward signs produced by classical chaotic systems are the same in quantum systems,” says Poul Jessen of Arizona State University, the lead researcher on the Nature paper.

In order to see these signatures, physicists have taken the conditions that cause chaotic behavior in human-scale systems and applied them on the atomic level. Jessen and his collaborators recently succeeded in making a quantum “kicked top” out of cesium atoms for the first time.

Kicked tops are an excellent example of chaotic systems when it comes to classic physics. You start an object twirling—say, a gyroscope—and then give it a series of kicks and twists as it spins. The initial condition that decides whether a gyroscope moves stably or chaotically is the direction of its axis when it starts spinning.

In order to visualize the gyroscope’s behaviour, the different values of its angular momentum are plotted on the surface of a globe. Some initial orientations of its axis cause the momentum to swerve in a “chaotic sea,” covering most of the surface of the globe. But other orientations cause the spin to settle into stable, regular motion in one of three main “islands” in the sea.

In their experiment, researchers substituted atoms for gyroscopes and looked at how angular momenta affected the atoms’ quantum states. What they found was intriguing: Some spins of the quantum top locked the atoms into a stable set of islands, while other values let the atoms’ quantum states wander erratically.

The number and location of the islands, when plotted, corresponded eerily to the classical model. So while the atoms’ behavior could not technically be called chaotic because they cannot show hypersensitivity, they mimicked the evolution of the classical, chaotic system almost exactly. Other measurements indicated that the system might have some sensitivity to disturbances, another interesting link to chaotic behaviour.

These observations alone provided good evidence that something related to chaos was happening. But the most fascinating result was that one of the strangest properties of atoms, entanglement, shot up in areas corresponding to the chaotic sea. When two quantum-scale objects, like atoms or nuclei, are entangled, performing an action on one instantaneously affects the other even if vast distances separate the entangled objects. Einstein famously called entanglement “spooky action at a distance,” and it forms the basis of modern attempts to built quantum computers.

Could entanglement be a signature of chaos?

Read the full article in Seed magazine ..............