amino acid repeats cause extraordinary coding sequence variation in the social amoeba dictyostelium discoideum氨基酸重复导致非凡的编码序列的变化社会变形虫dictyostelium discoideum.pdfVIP

Amino Acid Repeats Cause Extraordinary Coding Sequence Variation in the Social Amoeba Dictyostelium discoideum 1. 2. 1¤ 1 3 Clea Scala , Xiangjun Tian , Natasha J. Mehdiabadi , Margaret H. Smith , Gerda Saxer , 1 1 2 2 Katie Stephens , Prince Buzombo , Joan E. Strassmann , David C. Queller * 1 Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas, United States of America, 2 Department of Biology, Washington University in St. Louis, St. Louis, Missouri, United States of America, 3 Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America Abstract 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’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. Citation: Scala C, Tian X, Mehdiabadi NJ, Smith MH, Saxer G,