Recently, scientists of University of Texas Southwestern Medical Center (UT Southwestern) has revealed a new genetic code that determines protein functions, whose encoding mechanism plays a central role in biological processes.
Every cell in our body contains tens of thousands of proteins, and cells exercise their functions through these proteins. Amino acids are the basic units of proteins, which are connected to each other according to an instruction of the genetic code, and assembled into different types of proteins. The researchers of the UT Southwestern found that protein function depends not only on their amino acid sequence, also depends on the speed of the assembly of amino acids. The study published as the cover article in the last issue of the journal Molecular Cell.
It has long been known that each amino acid has a number of synonymous codons, different organisms (from humans to fungi) of these codons have their own preferences. Studies have shown that more frequent use of codon (preferred codons) can speed up the production chain of amino acids, and less use of the codon will slow down this process. These codons like speed limit signs on the road, control the protein production speed.
The genetic code, which is composed of nucleic acids, is the core of life, which not only specifies the amino acid sequence of the protein, but also controls the assembly and folding of proteins. Fast/slow codon usage determines the speed of the assembly of proteins, which in turn affects the protein folding. Such mechanism of the speed control of the genetic code can ensure the proper exercise of their functions of proteins in different cells.
The researchers showed that the same amino acid sequence with different assembly rate would form different proteins with different functions. This finding is of great significance for the identification of human pathogenic mutations. This study also suggests that disease-causing mutations may not need to change the amino acid sequence. In fact, the vast majority of human DNA mutations do not affect the amino acid sequence.
Codon Usage Influences the Local Rate of Translation Elongation to Regulate Co-translational Protein Folding, Molecular Cell.