Wednesday, December 3, 2014

Synthetic enzymes hint at life without DNA or RNA

Life might not have to be based on DNA or RNA <i>(Image: Mohamed Sadath/Getty)</i> 
Enzymes that don't exist in nature have been made from genetic material that doesn't exist in nature either, called XNA, or xeno nucleic acid.

It's the first time this has been done and the results reinforce the possibility that life could evolve without DNA or RNA, the two self-replicating molecules considered indispensible for life on Earth.

"Our work with XNA shows that there's no fundamental imperative for RNA and DNA to be prerequisites for life," says Philipp Holliger of the Laboratory of Molecular Biology in Cambridge, UK, the same laboratory where the structure of DNA was discovered in 1953 by Francis Crick and James Watson.

It's not all about the base

Holliger's team has made XNAs before. Their unnatural XNA contains the same bases – adenine, thymine, guanine, cytosine and uracil – on which DNA and RNA rely for coding hereditary information. What's different is the sugar to which each base is attached.

In DNA and RNA, the sugars are deoxyribose and ribose, respectively. Holliger made new types of genetic material by replacing these with different sugars or other molecules.

Now, they have taken a step closer to mimicking early life on the planet by showing that XNAs can also serve as enzymes – indispensible catalysts for speeding up chemical reactions vital for life.

One of the first steps towards life on Earth is thought to be the evolution of RNA into self-copying enzymes.

For the rest of the story: http://www.newscientist.com/article/dn26641-synthetic-enzymes-hint-at-life-without-dna-or-rna.html#.VH9sK8mOouh

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