Toxoplasma gondii H2B.Z histone acetylation is involved in parasite development

VANAGAS L; CRISTALDI, CONSTANZA; GANUZA A; SULLIVAN WJ; KIM K; ANGEL SO*

Woods Hole

Congreso; Annual Molecular Parasitology Meeting; 2021

Molecuar Parasitology Society

T. gondii and other apicomplexan parasites possess an unusual H2B variant called H2B.Z which is found in nucleosomes containing H2A.Z, another histone variant. H2A.Z and H2B.Z are positioned at transcription start sites (TSS) together with H3K4Me3 and both histone variants are highly acetylated at their N-terminal tails. We over-expressed myc-tagged H2B.Z in RH strain in which the acetylatable lysine residues were maintained (c-Myc-K-OE) or mutated to either the neutral amino acid alanine (c-Myc-A-OE) or the positively charged arginine (c-Myc-R-OE). c-Myc-A-OE and c-Myc-R-OE were used to disrupt the endogenous essential H2B.Z gene using CRISPR/Cas9. c-Myc-R/KO presented a lower growth rate and an increment in bradyzoite differentiation rate compared to the parental in vitro. Infection of C57BL/6 mice with 100 ? 10,000 c-Myc-R/KO tachyzoites showed no virulence, but elicited the expected immune response, and did not develop brain cysts. Mice previously infected with c-Myc-R/KO were protected from parental RH strain infection. ChIP-qPCR with anti-c-Myc and ?H2A.Z antibodies showed that neither H2B.Z nor H2A.Z were enriched in promoters of active and silent genes, in c-Myc-R/KO. c-Myc-A/KO did not show any phenotypical change in vitro and a modest delay in killing infected mice. These findings suggest that regulation of positive lysine charge of the N-terminal region of H2B.Z is relevant for the genome localization, which would regulate gene expression and, as a consequence would be important in the control of parasite development and survival during animal infection