Tópico: Códons sinônimos não são tão sinônimos assim, afetam a expressão gênica

[Buckaroo Banzai]

Biologists Discover How 'Silent' Mutations Influence Protein Production

ScienceDaily (Apr. 10, 2009) —

... Synonymous mutations do not change the amino-acid sequence of a protein, but they can nevertheless influence the amount of the protein that is produced. The researchers identified the mechanism underlying this regulation: synonymous mutations determine mRNA folding and thereby the eventual protein level. The researchers also identified a class of mutations that did not directly affect protein levels but slowed bacterial growth. ...

To answer this question, Joshua B. Plotkin, senior author and the Martin Meyerson Assistant Professor in the Department of Biology in Penn's School of Arts and Sciences, and colleagues at Harvard University and the University of Edinburgh engineered a synthetic library of 154 genes that varied randomly at synonymous sites. All the genes encoded the same green fluorescent protein, enabling the researchers to easily study the effects of such mutations on protein levels when expressed in the bacterium Escherichia coli.

The silent mutations changed the amount of fluorescent protein by as much as 250-fold, without changing the properties of the protein. Codon bias, the probability that one codon of three adjacent nucleotides will code for one amino acid over another, was previously thought to be the cause for protein expression variance, but it did not correlate with gene expression in these experiments. ...

http://www.sciencedaily.com/releases/2009/04/090409142258.htm