Essentiality of CENP-A Depends on Its Binding Mode to HJURP

CENP-A incorporation is critical for centromere specification and is mediated by the chaperone HJURP. The CENP-A-targeting domain (CATD) of CENP-A specifically binds to HJURP, and this binding is conserved. However, the binding interface of CENP-A-HJURP is yet to be understood. Here, we identify the critical residues for chicken CENP-A or HJURP. The A59Q mutation in the α1-helix of chicken CENP-A causes CENP-A mis-incorporation and subsequent cell death, whereas the corresponding mutation in human CENP-A does not. We also find that W53 of HJURP, which is a contact site of A59 in CENP-A, is also essential in chicken cells. Our comprehensive analyses reveal that the affinities of HJURP to CATD differ between chickens and humans. However, the introduction of two arginine residues to the chicken HJURP αA-helix suppresses CENP-A mis-incorporation in chicken cells expressing CENP-AA59Q. Our data explain the mechanisms and evolution of CENP-A essentiality by the CENP-A-HJURP interaction. [Display omitted] •Two binding modes are found for the HJURP-CENP-A interaction•The CENP-A α1-helix is critical in chicken cells but not in human cells•HJURP strongly interacts with CATD in humans, even with mutations in the CENP-A α1-helix•The enhanced HJURP-CATD binding suppresses a deficiency for the CENP-A α1-helix in chicken Hori at al. find a critical CENP-A residue in its α1-helix for HJURP interaction in chicken cells but not in human cells. They demonstrate that the essentiality of this residue depends on the affinities of HJURP to CENP-A, explaining a mechanism for evolution of CENP-A essentiality.