Methionine—tRNA ligase

Methionine—tRNA ligase is an enzyme that plays a crucial role in the process of protein synthesis within cells. This enzyme, also known as methionyl-tRNA synthetase, is responsible for the attachment of methionine to its corresponding transfer RNA (tRNA), a critical step in the initiation of protein synthesis. Methionine—tRNA ligase is encoded by the MARS gene in humans and is essential for the proper functioning of the genetic code and the synthesis of proteins necessary for cell survival and function.

Function

Methionine—tRNA ligase belongs to the class-I aminoacyl-tRNA synthetase family, enzymes that play a key role in the translation process of converting genetic information from mRNA into protein. This enzyme specifically catalyzes the ligation of methionine to its corresponding tRNA molecule, forming methionyl-tRNA. This reaction is ATP-dependent and occurs in two steps:

1. Activation of methionine by ATP to form methionyl-AMP
2. Transfer of methionine from methionyl-AMP to tRNA, resulting in methionyl-tRNA

Methionyl-tRNA is then utilized in the initiation of protein synthesis, as methionine is typically the first amino acid incorporated into nascent proteins in eukaryotic cells. This process is vital for the accurate translation of the genetic code into functional proteins.

Clinical Significance

Mutations in the MARS gene, which encodes the methionine—tRNA ligase enzyme, have been associated with various human diseases. These include Charcot-Marie-Tooth disease, a disorder affecting the peripheral nerves, and interstitial lung disease, among others. Understanding the function and regulation of this enzyme is crucial for developing therapeutic strategies for diseases caused by mutations in the MARS gene.

Evolution

Methionine—tRNA ligase is highly conserved across different species, highlighting its fundamental role in protein synthesis. Comparative studies of this enzyme in various organisms help in understanding the evolutionary adaptations of the protein synthesis machinery.

See Also

• Aminoacyl-tRNA synthetase
• Protein synthesis
• Transfer RNA
• Methionine