Aminoacyl-tRNA synthetase

Definition

Aminoacyl-tRNA synthetase is an essential enzyme that facilitates the attachment of the appropriate amino acid to its corresponding transfer RNA (tRNA) molecule, a crucial step in the process of translation and protein synthesis. This enzyme ensures that each tRNA carries the correct amino acid, enabling accurate translation of the genetic code into proteins. The specificity and accuracy of aminoacyl-tRNA synthetase play a vital role in maintaining the fidelity of protein synthesis, making it indispensable for cellular function.

5 Must Know Facts For Your Next Test

1. There are 20 different aminoacyl-tRNA synthetases, each specific to one amino acid and its corresponding tRNAs.
2. The enzyme catalyzes a two-step reaction: first, it activates the amino acid with ATP to form an aminoacyl-AMP intermediate, then it transfers the amino acid to the tRNA.
3. The accuracy of aminoacyl-tRNA synthetase directly influences the correctness of protein synthesis, as mischarging tRNAs can lead to faulty proteins.
4. Each synthetase has an active site that precisely recognizes both the amino acid and the tRNA, ensuring high specificity in its function.
5. Some aminoacyl-tRNA synthetases also have proofreading capabilities to correct any mistakes in charging tRNAs with their respective amino acids.

Review Questions

• How does aminoacyl-tRNA synthetase contribute to the accuracy of protein synthesis?
  • Aminoacyl-tRNA synthetase contributes to the accuracy of protein synthesis by ensuring that each tRNA is charged with the correct amino acid. It achieves this through its specificity for both the amino acid and its corresponding tRNAs, minimizing the risk of errors during translation. This precise pairing is crucial because even a single mistake in the amino acid sequence can lead to dysfunctional proteins and affect cellular function.
• What are the implications of errors made by aminoacyl-tRNA synthetase on cellular function?
  • Errors made by aminoacyl-tRNA synthetase can lead to incorrect amino acids being incorporated into proteins, resulting in dysfunctional or nonfunctional proteins. These faulty proteins can disrupt normal cellular processes, potentially leading to diseases or impairments in cell function. Additionally, such errors may also affect metabolic pathways and overall organismal health, highlighting the importance of this enzyme's fidelity.
• Evaluate how the specificity and proofreading capabilities of aminoacyl-tRNA synthetase influence evolutionary processes in living organisms.
  • The specificity and proofreading capabilities of aminoacyl-tRNA synthetase are crucial for maintaining high fidelity in protein synthesis, which is fundamental for cellular functions and organismal development. Over evolutionary time, organisms that possess more accurate enzymes are likely to have an advantage in producing functional proteins that support survival and adaptation. This increased accuracy can lead to better fitness and adaptability in changing environments, contributing to natural selection and evolution within species.

Related terms

tRNA:

Transfer RNA (tRNA) is a type of RNA molecule that transports specific amino acids to the ribosome during protein synthesis, matching them with the corresponding codons in the mRNA.

Translation: Translation is the process by which ribosomes synthesize proteins by decoding messenger RNA (mRNA) sequences into polypeptide chains, with the help of tRNA and aminoacyl-tRNA synthetase.

Codon: A codon is a sequence of three nucleotides in mRNA that specifies a particular amino acid or signals the termination of protein synthesis.