Evolutionary conservation of SSR sites
In 2009 Donald E. Riley and John N. Krieger (Dept. of Urology, Univ. of Washington, Seattle) published two back-to-back papers analyzing the evolution of simple sequence repeats (SSRs). These reports deserve more attention than they have so far received:
Riley, D.E. & J.N. Krieger. 2009. UTR dinucleotide simple sequence repeat evolution exhibits recurring patterns including regulatory sequence motif replacements. Gene 429: 80-86.
Riley, D.E. & J.N. Krieger. 2009. Embryonic nervous system genes predominate in searches for dinucleotide simple sequence repeats flanked by conserved sequences. Gene 429: 74-79.
What follows is excerpted from a poster which I presented at the 2009 annual meeting of the Society for Neuroscience. My primary purpose in presenting this poster was to highlight these papers by Riley and Krieger.
Riley & Krieger recently reported a peculiar category of SSR, found predominantly in genes involved in nervous system function and development.
These genes contain dinucleotide repeat (diSSR) sites with highly conserved upstream flanking sequences in their untranslated regions.
Among all the examples whose functions are known, most either are critical for mammalian nerve cells (such as ion channels, synapse-associated proteins, neurotransmitter receptors, axon pathfinders) or are expressed during embryonic nervous system development.
The function for such diSSRs remains unknown, but they are expected to influence folding of transcribed single-strand RNA.
Remarkably, most of these mutation-prone diSSR sites are conserved over deep evolutionary time.
It is the diSSR sites, not their specific motif sequences nor their numbers of repeats, that are conserved.
Conserved diSSR sites display recurring patterns of motif replacement in various mammalian lineages.
"Some function is evidently being preserved in the repetitive (and hypermutable) nature of these sites, one which can persist through, or perhaps even exploit, the accumulation of sequence- transforming mutations" [Science 326:229].
Comments and questions: dgking@siu.edu
SIUC / Zoology / David King
https://dgkinglab.siu.edu/RileyKrieger.htm
Last updated: 23 March 2023 / dgk