ATPase histone chaperone which facilitates loading of histone H3-H4 onto DNA in an ATP-dependent manner (PubMed:31848341, PubMed:33658433). Plays a genome-wide role in nucleosome organization and establishment of chromatin (PubMed:26582768, PubMed:31848341). Also plays a role in heterochromatin assembly by stabilizing recruitment of the histone methyltransferase clr4 to methylated histone H3, to promote the transition from H3K9me2 to H3K9me3 (PubMed:32269268). ATP + H2O = ADP + H(+) + phosphate Homohexamer (PubMed:31848341). Interacts with the FACT complex subunits spt16 and pob3 (PubMed:26582768). Interacts with histone H3-H4 (via N-terminus) (PubMed:31848341, PubMed:26582768). Abnormal nucleosome distribution (PubMed:26582768). Decreases level of clr4 at the subtelomeric and pericentromeric regions and at DSR (determinant of selective removal) islands containing meiotic genes; decreases di- and tri-methylation of histone H3 'Lys-9' at these regions (PubMed:32269268). Abnormal heterochromatin formation at the pericentromeric outer and inner repeat regions, the subtelomeric region, and the silenced mating-type locus (PubMed:26582768, PubMed:32269268). Impairs centromere function; leads to abnormal mitotic and meiotic chromosome segregation and sensitivity to thiabendazole (spindle poison) (PubMed:26582768). Decreases silencing of subtelomeric regions, including Tf2-type retrotransposons (PubMed:26582768, PubMed:32269268). Decreases histone H3 and H2A protein levels (PubMed:26582768). Abnormal transcription resulting in increased levels of cryptic transcripts (PubMed:26582768). Increases transcript levels of genes involved in the stress response (PubMed:26582768). Sensitive to methyl methanesulfonate (DNA damaging agent); double-knockout with nhp6, or triple-knockout with hht2 and hhf2 exacerbates the effect (PubMed:26582768). Sensitive to heat and cold; double-knockout with nhp6, clr3, clr4, or swi6, or triple-knockout with hht2 and hhf2 exacerbates the effect (PubMed:26582768, PubMed:32269268). Decreases cell viability and leads to slow cell population growth with elongated cells; double-knockout with clr4 or swi6 exacerbates the effect (PubMed:26582768, PubMed:32269268). Double knockout with abo2 results in lethality (PubMed:26582768). Belongs to the AAA ATPase family.