Shine–Dalgarno sequence

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Shine-Dalgarno sequence
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The Shine–Dalgarno (SD) sequence is a

tRNA
may add amino acids in sequence as dictated by the codons, moving downstream from the translational start site.

The Shine–Dalgarno sequence is common in

early genes.[1]

The Shine–Dalgarno sequence was proposed by Australian scientists John Shine and Lynn Dalgarno in 1973.

Recognition

Translation start sites

Using a method developed by Hunt,

3' end of E. coli 16S ribosomal RNA (rRNA) (that is, the end where translation begins) is pyrimidine-rich and has the specific sequence YACCUCCUUA. They proposed that these ribosomal nucleotides recognize the complementary purine-rich sequence AGGAGGU, which is found upstream of the start codon AUG in a number of mRNAs found in viruses that affect E. coli.[1] Many studies have confirmed that base pairing between the Shine–Dalgarno sequence in mRNA and the 3' end of 16S rRNA is of prime importance for initiation of translation by bacterial ribosomes.[5][6]

Given the complementary relationship between rRNA and the Shine–Dalgarno sequence in mRNA, it was proposed that the sequence at the 3'-end of the rRNA determines the capacity of the prokaryotic ribosome to translate a particular gene in an mRNA.[7] Base pairing between the 3'-end of the rRNA and the Shine–Dalgarno sequence in mRNA is a mechanism by which the cell can distinguish between initiator AUGs and internal and/or out-of-frame AUG sequences. The degree of base pairing also plays a role in determining the rate of initiation at different AUG initiator codons.

Translation termination

In 1973 Dalgarno and Shine proposed that in

F1 phage, a class of viruses that infect bacteria, the sequence coding for the first few amino acids often contains termination triplets in the two unused reading frames.[further explanation needed][10] In a commentary on this paper, it was noted that complementary base pairing with the 3'-terminus of 16S rRNA might serve to abort peptide bond formation after out-of-phase initiation.[11]

Sequence and protein expression

Mutations in the Shine–Dalgarno sequence can reduce or increase[12] translation in prokaryotes. This change is due to a reduced or increased mRNA-ribosome pairing efficiency, as evidenced by the fact that compensatory mutations in the 3'-terminal 16S rRNA sequence can restore translation.

See also

References

  1. ^
    S2CID 17854788
    .
  2. PMID 21265752
    .
  3. PMID 4321896
    .
  4. PMID 4197338
    .
  5. S2CID 36679385
    .
  6. PMID 1107998
    .
  7. S2CID 4162567
    .
  8. PMID 4202225
    .
  9. PMID 14340106
    .
  10. PMID 4375722
    .
  11. doi:10.1038/260012a0
    .
  12. PMID 1826903
    .

Further reading

External links
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