MIT Scientists Decipher Second Genetic Code Essential to Life

NEW YORK — Scientists said Thursday they have taken the first step toward deciphering a second genetic code essential to life and have shown that it is simpler and more powerful than they expected.

“It looks like an elegantly simple logic that’s remained obscure for all these years, but I think we’re finally getting a handle on it,” said one of the researchers, Paul Schimmel, a biochemist at the Massachusetts Institute of Technology in Cambridge.

“It’s a spectacular example of biological logic, or the logical system that nature uses,” he said in a telephone interview Thursday.

Deciphering the code could help doctors understand and possibly treat some genetic diseases, he said.

Schimmel said the logic of the second code could have application in development of new logics for computers.

‘May Be Instructive’

“Here’s an example of nature’s logic,” Schimmel said. “As we work it out, it may be instructive as we design new systems for computers. Nature’s logic is simple, but it’s also profound and has a powerful logical capability.”

But the importance of the finding lies primarily in its elucidation of a longstanding biological mystery, however, not in any short-term practical applications, he said.

The second code governs the final assembly of proteins inside living cells, and works with the original genetic code, Schimmel said. Its existence has been known for decades, but until now it has not been deciphered, he said.

A report of his findings appeared Thursday in Nature, a British scientific journal.

The original genetic code was deciphered in 1961. Researchers found that the sequence of distinct chemical subunits in the genetic material DNA, or deoxyribonucleic acid, determined which protein would be made by that gene.

A Change in Protein

A change in the DNA sequence results in a change in the protein.

DNA doesn’t make proteins directly, however. It hands off its instructions to a chemical called messenger RNA, which in turn relays the information to a third chemical called transfer RNA.

The transfer RNA then uses a second genetic code to actually assemble proteins from their amino acid building blocks.

Schimmel and his MIT colleague, Ya-Ming Hou, broke the code for the amino acid called alanine. (Each molecule of transfer RNA is coded for one of the 20 amino acids.)

DNA and RNA molecules are made up of subunits called base pairs. The MIT researchers found to their surprise that the code for alanine was carried in a single base pair on the alanine transfer RNA molecule.

It should now be a straightforward process to decipher the transfer RNA codes for the remaining 19 amino acids, Schimmel said.