methionyl-tRNA aminoacylation

Definition

Target type: biologicalprocess

The process of coupling methionine to methionyl-tRNA, catalyzed by methionyl-tRNA synthetase. The methionyl-tRNA synthetase is a class-I synthetase. The activated amino acid is transferred to the 2'-OH group of a methionine-accetping tRNA. The 2'-O-aminoacyl-tRNA will ultimately migrate to the 3' position via transesterification. [GOC:mcc, ISBN:0716730510]

Methionyl-tRNA aminoacylation is a fundamental biological process that involves the attachment of the amino acid methionine (Met) to its cognate transfer RNA (tRNA), specifically tRNAu003csupu003eMetu003c/supu003e. This reaction is catalyzed by methionyl-tRNA synthetase (MetRS), a highly specific enzyme that plays a crucial role in protein synthesis.

The process can be divided into two main steps:

**Step 1: Activation of Methionine**

* MetRS first binds to ATP and methionine, forming a complex.
* The enzyme then catalyzes the transfer of AMP from ATP to methionine, generating methionine adenylate (Met-AMP) and releasing pyrophosphate (PPi).
* This step is an energy-requiring reaction, and the energy is provided by the hydrolysis of ATP to AMP and PPi.

**Step 2: Transfer of Methionine to tRNAu003csupu003eMetu003c/supu003e**

* The activated methionine (Met-AMP) remains bound to MetRS.
* tRNAu003csupu003eMetu003c/supu003e then binds to the enzyme-substrate complex.
* MetRS catalyzes the transfer of methionine from Met-AMP to the 3'-end of tRNAu003csupu003eMetu003c/supu003e, forming methionyl-tRNAu003csupu003eMetu003c/supu003e.
* AMP is released as a byproduct.

The resulting methionyl-tRNAu003csupu003eMetu003c/supu003e is now ready to participate in protein synthesis, where it serves as the initiator tRNA, delivering methionine to the ribosome to start the formation of a polypeptide chain.

**Specificity of MetRS:**

* MetRS exhibits high specificity for both methionine and tRNAu003csupu003eMetu003c/supu003e.
* It possesses a unique active site that recognizes and binds to the specific structural features of methionine and tRNAu003csupu003eMetu003c/supu003e.
* This specificity ensures that the correct amino acid is attached to the correct tRNA, preventing errors in protein synthesis.

**Regulation of Methionyl-tRNA Aminoacylation:**

* The activity of MetRS is tightly regulated to ensure an adequate supply of methionyl-tRNAu003csupu003eMetu003c/supu003e for protein synthesis.
* Regulation can occur at various levels, including transcriptional and post-translational mechanisms.
* These regulatory mechanisms are important for maintaining cellular homeostasis and responding to changes in environmental conditions.

In summary, methionyl-tRNA aminoacylation is a highly specific and tightly regulated process that is essential for protein synthesis. It involves the activation of methionine and its subsequent transfer to tRNAu003csupu003eMetu003c/supu003e, generating the initiator tRNA that plays a critical role in the initiation of protein translation.'
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Proteins (1)

Compounds (1)