Study Reveals Key Step in Protein Synthesis

Scientists at the University of California, Sta. Cruz have trapped the ribosome, a protein-building molecular machine essential to all life, in a key transitional state. For the first time, scientists can see how the ribosome translates genetic code into proteins in a precise manner without making mistakes.

In making a new protein, genetic instructions are first copied from the DNA sequence of a gene to a messenger RNA molecule. The sequence is read by the ribosome which matches each three-letter codon of genetic code with a specific protein building block, one of 20 amino acids. The matching of codons to amino acids is done through transfer RNA molecules, each carrying a specific amino acid to the ribosome and lines it up with the matching codon on the messenger RNA.

The key step, called translocation, occurs after the bond is formed, joining a new amino acid to the growing protein chain. The transfer RNA leaves that amino acid behind and moves to the next site on the ribosome, along with a synchronous movement of the messenger RNA to bring the next codon and its associated amino acid into position for bond formation. The new study shows the ribosome in the midst of a key step in this process.

For more details about this study, read the news release from the UC Sta. Cruz at http://news.ucsc.edu/2013/06/ribosome.html.