The evolutionary dynamics of alpha-satellite

• Published in: Genome Research 2006-01, Vol.16 (1), p.88-96
• Main Authors: Rudd, M Katharine, Wray, Gregory A, Willard, Huntington F
• Format: Article
• Language: English
• Subjects: Animals; Centromere - genetics; Chromosomes, Human, Pair 17 - genetics; DNA, Satellite - genetics; Evolution, Molecular; Genome, Human - genetics; Humans; Letters; Models, Genetic; Pan troglodytes - genetics
• ISSN: 1088-9051; 1549-5469; 1549-5477
• DOI: 10.1101/gr.3810906

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.