The evolutionary dynamics of alpha-satellite.
Alpha-satellite is a family of tandemly repeated sequences found at all normal human centromeres. In addition to its significance for understanding centromere function, alpha-satellite is also a model for concerted evolution, as alpha-satellite repeats are more similar within a species than between species. There are two types of alpha-satellite in the human genome; while both are made up of approximately 171-bp monomers, they can be distinguished by whether monomers are arranged in extremely homogeneous higher-order, multimeric repeat units or exist as more divergent monomeric alpha-satellite that lacks any multimeric periodicity. In this study, as a model to examine the genomic and evolutionary relationships between these two types, we have focused on the chromosome 17 centromeric region that has reached both higher-order and monomeric alpha-satellite in the human genome assembly. Monomeric and higher-order alpha-satellites on chromosome 17 are phylogenetically distinct, consistent with a model in which higher-order evolved independently of monomeric alpha-satellite. Comparative analysis between human chromosome 17 and the orthologous chimpanzee chromosome indicates that monomeric alpha-satellite is evolving at approximately the same rate as the adjacent non-alpha-satellite DNA. However, higher-order alpha-satellite is less conserved, suggesting different evolutionary rates for the two types of alpha-satellite.
Rudd
M Katharine
MK
Institute for Genome Sciences & Policy, Duke University, Durham, North Carolina 27708, USA.
Wray
Gregory A
GA
Willard
Huntington F
HF
D000818:Animals; D002503:Centromere / Q000235:genetics*; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics*; D004276:DNA, Satellite / Q000235:genetics*; D019143:Evolution, Molecular; D015894:Genome, Human / Q000235:genetics*; D006801:Humans; D008957:Models, Genetic; D002679:Pan troglodytes / Q000235:genetics
D004276:DNA, Satellite