Evolution of Alpha‐Satellite DNA

Abstract

Abstract Alpha satellite deoxyribonucleic acid (DNA) is based on 171 bp tandem repeats located in the centromeric and pericentromeric regions of all primate chromosomes. In humans, most of the alpha satellite repeats are organised in a hierarchical fashion, creating complex units called higher order repeats, composed of 2 to more than 30 diverged monomers in length. Monomeric alpha satellite DNA predates higher order arrays of alpha satellite and may represent direct descendant of the ancestral primate centromere sequence. Comparison of centromeric alpha satellite DNA sequences in different primate species reveals that alpha satellite DNA evolves through a series of amplification events resulting in the spreading of ‘new’ subfamilies, which replace the ‘old’ ones and confer centromere function. Transcripts of alpha satellite play an important role in kinetochore formation and the establishment of pericentromeric heterochromatin and are indispensable for the proper cell division. Key Concepts: Complex higher order repeats (HORs) are predominant form of alpha satellite DNA in the great ape and humans. Alpha satellite HORs evolve much faster than monomers and contribute substantially to divergence between chromosomes of primates. Two distinct chromosomal domains, the centromere and heterochromatin are assembled and maintained on the alpha satellite DNA sequence. Alpha satellite DNA evolves through proximal amplification events occurring within the central active region of the centromere. Transcription of alpha satellite DNA is crucial for centromere/kinetochore assembly and function during cell division.