Discovery Narrows Search For Precursor Of All Life Forms

New Haven, Conn. -- Yale scientists report they have synthesized molecules like those that probably gave rise to the earliest life forms on Earth nearly 4 billion years ago, thus creating a biochemist's version of "Jurassic Park" populated by exotic molecular "fossils" that have long since become extinct.

In the May 26 issue of the Proceedings of the National Academy of Sciences, the Yale biologists report the creation of one of these "fossils," an unusual hybrid molecule made up of a scaffold from deoxyribonucleic acid (DNA) with chemical "scissors" attached to it.

Ronald R. Breaker, who created the first DNA enzymes in 1994 with colleagues at The Scripps Research Institute, said he "looted the tool box of proteins" to get the amino acid "scissors," which destroy messenger ribonucleic acid (RNA) in humans and many other organisms. The feat was accomplished using a technique known as test-tube evolution.

Breaker's tailor-made enzyme is the first known nucleic acid enzyme that uses an amino acid to trigger chemical activity, and it brings scientists a step closer to finding the precursor of all life -- a single molecule containing both genetic code and an enzyme capable of triggering self-replication.

"If we can raid a protein's tool box to take one of its favored chemical groups -- in this case, a key amino acid called histidine found in a protein called RNase A -- then we should be able to raid the entire tool box and make use of anything we find there to make highly sophisticated DNA or RNA enzymes," said Breaker, who collaborated with Yale postdoctoral associate Adam Roth.

Which Came First -- DNA, RNA Or Proteins?

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Contact: Cynthia Atwood
Cynthia.Atwood@yale.edu
203-432-1326
Yale University
5-Jun-1998