Question

What is the role of aminoacyl-tRNA synthetase? The ability of aminoacyl-tRNA synthetases to recognize tRNAs has sometimes been called the "second genetic code." Why has the function of this type of enzyme been described this way?

Short answer

Aminoacyl-tRNA synthetase catalyzes the esterification of a specific amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. This matching of amino acids to tRNAs is critical to the protein synthesis process and forms an additional layer of 'coding' or 'interpretation' which is why the function of this enzyme is referred to as the 'second genetic code'.

Step-by-step solution

Role of Aminoacyl-tRNA Synthetase

Aminoacyl-tRNA synthetase plays a critical role in protein synthesis. This enzyme attaches the appropriate amino acid onto its tRNA. It does this by catalyzing the esterification of a specific amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA.

Why is it called the 'Second Genetic Code'

The function of aminoacyl-tRNA synthetase has been described as the 'second genetic code' because it essentially interprets the genetic code. In other words, it pairs the right amino acid with its corresponding tRNA. This pairing process is crucial to ensure that the amino acids are correctly inserted into the polypeptide chain as per the mRNA code during translation. This critical step influences the fidelity of protein synthesis, essentially adding an extra layer of 'interpretation' or 'coding' to the process, hence the term 'second genetic code'.