Sim3 Shares Some Common Roles With the Histone Chaperone Asf1 in Fission Yeast

An H3/H4 histone chaperone, Asf1, plays an essent ial role in maintaining genomic stabil i ty in many species, including f ission yeast . Here, we showed that overexpression of a CENP-A chaperone Sim3 suppres sed the temperature sensi t i ve phenotype of asf1-33 and asf1-30 mutants and the defect in chromat in st ructure, and prevented the accumulat ion of DNA damage in asf1-33 mutants at high temperatures. Fur thermore, asf1-33 and Δsim3 were synthet ic lethal . Consistent with this, shutdown of s im3 expression in asf1-33 Δsim3 double mutants that contained extragenic s im3 resul ted in growth retardat ion. In addi t ion, the Δs im3 mutant displayed sens i t ivi ty to thiabendazol and hydroxyurea, which suggests that Sim3 plays a general role in maintaining chromatin st ructur e . Our resul ts sugges t a possibil i ty that Sim3 funct ions as a histone chaperone.