Tantalizing clues to the chemical origins of life

Tantalizing clues to the chemical origins of life
A synthetic molecule can reshuffle itself to match a DNA template.
Katharine Sanderson Published online 12 June 2009 | Nature(**tantalizing=tentador,utópico)
The new molecule can adapt its sequence to a DNA template.Science / AAAS
Chemists in the United States have made an artificial DNA-like molecule that can change its sequence to bind to a DNA template without the help of enzymes. The findings could shed light on how molecules underpinning life were first able to emerge from a chemical soup.
The vexing question of how strands of DNA or RNA might have first formed has led many chemists to try and recreate the situation in the lab, using synthetic molecules that stack together to form DNA-like strands. Now, Reza Ghadiri at the Scripps Research Institute in La Jolla, California, has taken a different tack — coming up with a molecule that can pair up with different sequences of DNA by rearranging its own sequence.
RNA and DNA both have a backbone made from sugars and phosphorous-containing units called phosphates. Each unit of the DNA or RNA strand also contains one of four bases. The sequence of these bases — adenine, thymine, guanine and cytosine in the case of DNA — forms the genetic code.
Scientists trying to make self-replicating systems have constructed long DNA- and RNA-like molecules from small, information-carrying units that stack together, in the same way that DNA stacks together from nucleotide units in nature. The problem with these is that, once assembled, the sequence of bases cannot usually be changed.
Ghadiri, however, tried a different approach, hoping to find a method of anchoring bases reversibly so that they bind to the backbone but can also come off again.