Unstable Tandem Repeats in Promoters Confer Transcriptional Evolvability

It is widely known that large sections of DNA are non-coding regions. Tandem repeats (TRs), which are short stretches of DNA that are repeated head-to-tail, have been found to influence the activity of neighbouring genes.

It has been found that TRs preferentially form in nucleosome-free regions and thus controls nucleosome positioning. This directly affects the chromatin structure which in turn, alters gene activity. It was also found that variation in TR length will result in a change in nucleosome positioning.

Researchers also found that promoters containing TRs showed significantly higher amounts of expression divergence than promoters lacking TRs. They concluded that genes driven by TRs have significantly higher rates of transcriptional divergence.

It was concluded that TRs are variable elements in promoters which allows for shifts in gene activity and thus facilitate the evolution of gene expression. These pieces of DNA which were labelled as ‘junk’ pieces of DNA, may actually be enabling organisms to quickly adapt to changes in their environment by altering gene activity.

Article can be viewed at:

Vinces, Legendre, Caldara, Hagihara & Verstrepen 2009, ‘Unstable tandem repeats in promoters confer transcriptional evolvability’, Science, 324, 5931, pp. 1213-1216.

Science Daily 2009, Saved by junk DNA: Vital role in the evolution of human genome, viewed 1 June 2009, http://www.sciencedaily.com/releases/2009/05/090528203730.htm.