A hidden and never before recognized layer of information in the genetic code has been uncovered by a team of scientists at the University of California, San Francisco (UCSF) thanks to a technique developed at UCSF called ribosome profiling, which enables the measurement of gene activity inside living cells — including the speed with which proteins are made.
By measuring the rate of protein production in bacteria, the team discovered that slight genetic alterations could have a dramatic effect. This was true even for seemingly insignificant genetic changes known as “silent mutations,” which swap out a single DNA letter without changing the ultimate gene product. To their surprise, the scientists found these changes can slow the protein production process to one-tenth of its normal speed or less.
As described today in the journal Nature, the speed change is caused by information contained in what are known as redundant codons — small pieces of DNA that form part of the genetic code. They were called “redundant” because they were previously thought to contain duplicative rather than unique instructions.