Formation of functional CENP-B boxes at diverse locations in repeat units of centromeric DNA in New World monkeys

Kazuto Kugou,Akihiko Koga,Hiroshi Masumoto,Hirohisa Hirai

doi:10.1038/srep27833

Abstract

Centromere protein B, which is involved in centromere formation, binds to centromeric repetitive DNA by recognizing a nucleotide motif called the CENP-B box. Humans have large numbers of CENP-B boxes in the centromeric repetitive DNA of their autosomes and X chromosome. The current understanding is that these CENP-B boxes are located at identical positions in the repeat units of centromeric DNA. Great apes also have CENP-B boxes in locations that are identical to humans. The purpose of the present study was to examine the location of CENP-B box in New World monkeys. We recently identified CENP-B box in one species of New World monkeys (marmosets). In this study, we found functional CENP-B boxes in CENP-A-assembled repeat units of centromeric DNA in 2 additional New World monkeys (squirrel monkeys and tamarins) by immunostaining and ChIP-qPCR analyses. The locations of the 3 CENP-B boxes in the repeat units differed from one another. The repeat unit size of centromeric DNA of New World monkeys (340–350 bp) is approximately twice that of humans and great apes (171 bp). This might be, associated with higher-order repeat structures of centromeric DNA, a factor for the observed variation in the CENP-B box location in New World monkeys.

Highlights

The centromere is the part of a chromosome to which spindle fibers attach via the kinetochore and serves as the forefront of chromosome migration during cell division
With respect to functional constraints, even if a CENP-B box sequence is formed by mutations in centromeric DNA, it may not function or may function poorly when it arises at a different position in the repeat units
By immunofluorescence staining of cultured cells, we observed the co-localization of CENP-A and CENP-B accumulation signals in 4 of the 6 New World monkey species examined

Summary

Introduction

The centromere is the part of a chromosome to which spindle fibers attach via the kinetochore and serves as the forefront of chromosome migration during cell division. The location of CENP-B box in the repeat units of centromeric DNA in the great apes is identical to that in humans[11]. This uniform location might be a result of functional constraints or evolutionary processes. With respect to functional constraints, even if a CENP-B box sequence is formed by mutations in centromeric DNA, it may not function or may function poorly when it arises at a different position in the repeat units. The evolutionary process explanation suggests that the CENP-B boxes present in extant hominid species (humans and great apes) may have been derived from a CENP-B box that occurred in their common ancestor and/or from CENP-B boxes that emerged recurrently at this particular position in multiple lineages. These results provide molecular evidence for the existence of multiple, functional CENP-B boxes

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