Amino Acid Repeats Cause Extraordinary Coding Sequence Variation in the Social Amoeba Dictyostelium discoideum

作者：Scala Clea; Tian Xiangjun; Mehdiabadi Natasha J; Smith Margaret H; Saxer Gerda; Stephens Katie; Buzombo Prince; Strassmann Joan E; Queller David C^*

来源：PLos One, 2012, 7(9): e46150.

DOI：10.1371/journal.pone.0046150

Protein sequences are normally the most conserved elements of genomes owing to purifying selection to maintain their functions. We document an extraordinary amount of within-species protein sequence variation in the model eukaryote Dictyostelium discoideum stemming from triplet DNA repeats coding for long strings of single amino acids. D. discoideum has a very large number of such strings, many of which are polyglutamine repeats, the same sequence that causes various human neurological disorders in humans, like Huntington%26apos;s disease. We show here that D. discoideum coding repeat loci are highly variable among individuals, making D. discoideum a candidate for the most variable proteome. The coding repeat loci are not significantly less variable than similar non-coding triplet repeats. This pattern is consistent with these amino-acid repeats being largely non-functional sequences evolving primarily by mutation and drift.

• 出版日期2012-9-28