Developmental biology - Cell Chirality|
Taking A Chiral Path Through The Looking-Glass
Cellular molecules posess momentum from the direction they spin in order to attach to another molecule...
Like our hands, many molecules in nature exist in two versions that are mirror images of each other. Handedness, or chirality, only occurs naturally in some types of molecules and is from the ancient Greek word for hand - "cheir". It explains the workings of molecules and could pave the way for science to make new molecular bonds.
Exploring the mystery of 'right or left' handed molecules, a research team from DESY (Deutsches Elektronen-Synchrotron), Universität Hamburg and University College London propose a new way to create custom-made mirror molecules. Why? Because this technique can make ordinary molecules spin so fast - they lose their normal symmetry and shape, form mirrored versions of each other — and into new substances. Also, to understand why proteinds prefer left handed chirality. Group leader Jochen Küpper writes about this innovative methodology in the journal Physical Review Letters.
"If these molecules are stirred fast enough, they lose their symmetry and form two mirror forms, depending on their sense of rotation. So far, very little is known about this phenomenon of rotationally-induced chirality, because hardly any methods for its generation exist that can be followed experimentally."
"For unknown reasons, life as we know it on Earth almost exclusively prefers left-handed proteins, while the genome is organised as the famous right-handed double helix," explains Andrey Yachmenev, who lead this theoretical work in Küpper's group at the Center for Free-Electron Laser Science (CFEL). "For more than a century, researchers are unravelling the secrets of this handedness in nature, which does not only affect the living world: mirror versions of certain molecules alter chemical reactions and change the behaviour of materials."
An example of the dual nature of chirality: the right-handed version of caravone (C10H14O) gives caraway seed its distinctive taste, while the left-handed version is key to the taste of spearmint.
Küpper's team has now computationally devised a way to achieve induced chirality within realistic parameters in the lab using corkscrew-shaped laser pulses known as optical centrifuges. Testing their quantum-mechanical calculations on phosphine (PH3), they show that at rotation rates of trillions of times per second the phosphorus-hydrogen bond that the molecule rotates around becomes shorter than the other two of these bonds. Depending on the sense of rotation, two chiral forms of phosphine emerge.
Explains Yachmenev: "Using a strong static electric field, the left-handed or right-handed version of the spinning phosphine can be selected." The method promises a completely new path through the looking-glass into the mirror world, and should in principle also work with heavier molecules that would require weaker laser pulses and electric fields. Heavier and slower molecules are preferred for now as they are less toxic than phosphene.
Spinning new chiral bonds could deliver tailor-made mirror molecules, and generate new investigations into molecular interactions within the environment. According to Küpper, a professor of physics and chemistry at Universität Hamburg, "Faciliating a deeper understanding of the phenomenon of handedness could contribute to the development of chirality-based tailor-made molecules and materials, novel states of matter, and has potential use in novel metamaterials or optical devices."
Knowing which proteins and RNAs directly interact is essential for understanding cellular mechanisms. Unfortunately, discovering such interactions is costly and often unreliable. To overcome these limitations, we developed rec-YnH, a new yeast two and three-hybrid-based screening pipeline capable of detecting interactions within protein libraries or between protein libraries and RNA fragment pools. rec-YnH combines batch cloning and transformation with intracellular homologous recombination to generate bait–prey fusion libraries. By developing interaction selection in liquid–gels and using an ORF sequence-based readout of interactions via next-generation sequencing, we eliminate laborious plating and barcoding steps required by existing methods. We use rec-Y2H to simultaneously map interactions of protein domains and reveal novel putative interactors of PAR proteins. We further employ rec-Y2H to predict the architecture of published coprecipitated complexes. Finally, we use rec-Y3H to map interactions between multiple RNA-binding proteins and RNAs—the first time interactions between protein and RNA pools are simultaneously detected.
Alec Owens, Andrey Yachmenev, Sergei N. Yurchenko and Jochen Küpper./span>
DESY (short for Deutsches Elektronen-Synchrotron) is one of the world's leading particle accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety - ranging from the interaction of tiny elementary particles to the behaviour of innovative nanomaterials and the vital processes that take place between biomolecules to the great mysteries of the universe. The accelerators and detectors that DESY develops and builds at its locations in Hamburg and Zeuthen are unique research tools. DESY is a member of the Helmholtz Association, and receives its funding from the German Federal Ministry of Education and Research (BMBF) (90 per cent) and the German federal states of Hamburg and Brandenburg (10 per cent).
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When rotated rapidly, symmetric molecules like phosphine (PH) lose symmetry. The bond between phosphorus (GOLD) and hydrogen(SHORT ROD) along the axis of rotation, is shorter than its other two bonds (shadows represent movement). Credit: DESY, Andrey Yachmenev. Questions on chirality? Visit Khan Academy