Schizosaccharomyces pombe centromere protein M is19 links M is16 and M is18 to recruit CENP ‐A through interacting with NMD factors and the SWI / SNF complex

CENP ‐ A is a centromere‐specific variant of histone H 3 that is required for accurate chromosome segregation. The fission yeast S chizosaccharomyces pombe and mammalian M is16 and M is18 form a complex essential for CENP ‐ A recruitment to centromeres. It is unclear, however, how the M is16‐ M is18 complex achieves this function. Here, we identified, by mass spectrometry, novel fission yeast centromere proteins M is19 and M is20 that directly interact with M is16 and M is18. Like M is18, M is19 and M is20 are localized at the centromeres during interphase, but not in mitosis. Inactivation of M is19 in a newly isolated temperature‐sensitive mutant resulted in CENP ‐ A delocalization and massive chromosome missegregation, whereas Mis20 was dispensable for proper chromosome segregation. M is19 might be a bridge component for M is16 and M is18. We isolated extragenic suppressor mutants for temperature‐sensitive mis18 and mis19 mutants and used whole‐genome sequencing to determine the mutated sites. We identified two groups of loss‐of‐function suppressor mutations in non‐sense‐mediated m RNA decay factors ( upf2 and ebs1 ), and in SWI / SNF chromatin‐remodeling components ( snf5 , snf22 and sol1 ). Our results suggest that the M is16‐ M is18‐ M is19‐ M is20 CENP ‐ A ‐recruiting complex, which is functional in the G 1‐ S phase, may be counteracted by the SWI / SNF chromatin‐remodeling complex and non‐sense‐mediated m RNA decay, which may prevent CENP ‐ A deposition at the centromere.