The CENP-B box, a nucleotide motif involved in centromere formation, has multiple origins in New World monkeys

Centromere protein B (CENP-B), a protein participating in centromere formation, binds to centromere satellite DNA by recognizing a 17-bp motif called the CENP-B box. This motif is found in hominids (humans and great apes) at an identical location in repeat units of their centromere satellite DNA. We have recently reported that the CENP-B box exists at diverse locations in three New World monkey species (marmoset, squirrel monkey and tamarin). However, the evolutionary origin of the CENP-B box in these species was not determined. It could have been present in a common ancestor, or emerged multiple times in different lineages. Here we present results of a phylogenetic analysis of centromere satellite DNA that support the multiple emergence hypothesis. Repeat units almost invariably formed monophyletic groups in each species and the CENP-B box location was unique for each species. The CENP-B box is not essential for the immediate survival of its host organism. On the other hand, it is known to be required for de novo centromere assembly. Our results suggest that the CENP-B box confers a long-term selective advantage. For example, it may play a pivotal role when a centromere is accidentally lost or impaired.