Question

How to prove that Shine-Dalgarno sequence is important for protein translation?

Answer 1

We know that codons are read in a group of three. For this, we need the ribosome to know where to start.

Let us take a simple example.

“Our cat can see the mat.”

This sentence makes complete sense. However, if we shift the starting point even by one position, the sentence may be read as

“Urc at cans eet hem at”

Which completely changes the meaning.

Thus, ‘Shine-Dalgarno’ sequence provides the correct binding site for the ribosome on messenger RNA. The position of this sequence is approximately 8 bases upstream of the start site codon ‘AUG’. It helps to recruit and align the ribosome to the mRNA thus initiating protein synthesis.

This sequence is present in both bacteria and archaeas well as in certain mitochondrial and chloroplast transcripts in eukaryotes.

The Shine-Dalgarno sequence is complementary to the 3’ end of the ribosomal RNA. The consensus sequence is 5’-UAAGGAGG-3’ subsequently followed by the initiation codon AUG.