Researchers at Tsinghua University in Beijing have created a mirror-image version of a protein that performs two of the most fundamental processes of life: copying DNA and transcribing it into RNA. The work is a “small step” along the way to making mirror-image life forms, says molecular biologist Jack Szostak of Harvard Medical School in Boston, Massachusetts. “It’s a terrific milestone,” adds his Harvard colleague George Church, who hopes one day to create an entire mirror-image cell. Many organic molecules are ‘chiral’: that is, they can exist in mirror-image forms that cannot be superimposed, like a right-handed and left-handed glove. But life almost always employs one version: cells use left-handed amino acids, and have DNA that twists like a right-handed screw, for instance. In principle, looking-glass versions of these molecules should work together in the same way as normal ones — but they might be resistant to attack by conventional viruses or enzymes that have not evolved in a looking-glass world. http://www.nature.com/news/mirror-image-enzyme-copies-looking-glass-dna-1.19918
This discovery moves us one step closer to making synthetic organisms with reverse biochemistry. One of the great mysteries of life concerns what is called life's "chirality"—that is, its "handedness." Just like you and I, the very macromolecules that make up our cells exhibit "left-handed" or "right-handed" tendencies; it’s strange and maybe counterintuitive, but a molecule of a certain chirality is incompatible with its mirror-image complement, like a right-handed and left-handed glove. In the case of terrestrial life, amino acids are always left-handed, and DNA twists in a clockwise fashion. Now, this "small step" toward the creation of mirror-image organisms, that Chinese reserachers took by managing to synthesize a polymerase enzyme that can copy DNA and render it into RNA, means the possibility of generating synthetic life forms founded upon a reverse biochemistry and capable of self-replication. Aside from its superficial resemblance to a “mad scientist” scheme, the creation of a functioning mirror-image biochemistry has many important practical implications. For example, enzymes and other biomolecules of opposite chirality could be synthesized for medical purposes—they might be immune to attack by viruses or resistant to the biochemistry of ordinary bacteria. http://futurism.com/newest-discover...ynthetic-organisms-with-reverse-biochemistry/
