Question

How and when does formylmethionine become attached to the initiator tRNA in bacteria?

Short answer

Formylmethionine (fMet) is attached to the initiator tRNA in bacteria during the initiation of protein synthesis. A formyl group is added to tRNA-bound methionine by the enzyme methionyl-tRNA transformylase, transforming it into formylmethionine. It's important to note that this initiation is specific to prokaryotes.

Step-by-step solution

Understand Role of tRNA

tRNA (transfer RNA) is an integral part of protein synthesis. It aids in the process by bringing specific amino acids to the ribosome as per the instructions on the mRNA. The initiator tRNA is the first tRNA molecule to bind to the mRNA during the initiation of protein synthesis.

Understand the Role of Formylmethionine

Formylmethionine (fMet) is a modified amino acid used by bacteria, mitochondria, and plastids, as the first amino acid of every protein. This modification involves the addition of a formyl group to methionine. Consequently, the first position in the mRNA is usually coding for methionine in eukaryotes and formylmethionine in prokaryotes.

Attachment of Formylmethionine to tRNA

In bacteria, formylmethionine becomes attached to the initiator tRNA when a special enzyme known as methionyl-tRNA transformylase adds a formyl group (derived from formic acid) to the methionine amino acid already bound to the tRNA. This attachment occurs during the initiation of protein synthesis.