Centromeres are regions of chromosomes specialised for tethering the spindle microtubules and withstanding the pulling forces during chromosome segregation. In most species the centromeric identity depends on the timely deposition of a histone H3 variant called CENP-A. This process is tightly regulated, in part by post-translational modifications of CENP-A, its chaperones and licensing factors. In the holocentric nematode Caenorhabditis elegans, KNL-2 (M18BP1) is the crucial factor for CENP-A recruitment, but the spatiotemporal regulation of its function remains unknown. In this thesis, we examine KNL-2 localisation and post-translational modifications. We find that a pool of KNL-2 is sequestered in nucleoli in interphase and re locates to chromatin in prophase thanks to CDK¬1 activity. We show that KNL-2 phosphorylation regulates condensin II levels on chromatin and that KNL-2 functions in CENP-A loading and chromosome condensation are independent. Finally, we optimise a proteomic approach (APEX2), to discover new interactors of KNL-2 and CENP-A.