Histone variant H2B.Z acetylation is necessary for maintenance of Toxoplasma gondii biological fitness

• Published in: Biochimica et biophysica acta. Gene regulatory mechanisms Vol. 1866; no. 3; p. 194943
• Main Authors: Vanagas, Laura, Muñoz, Daniela, Cristaldi, Constanza, Ganuza, Agustina, Nájera, Rosario, Bonardi, Mabel C., Turowski, Valeria R., Guzman, Fanny, Deng, Bin, Kim, Kami, Sullivan, William J., Angel, Sergio O.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.09.2023
• Subjects: Acetylation; Animals; Cell cycle; Differentiation; Histones - metabolism; Mice; Mitosis; Nucleosomes - metabolism; Positive charge patch; Protein Processing, Post-Translational; Toxoplasma - genetics; Virulence; Positive charge patch; Differentiation; Mitosis; Virulence; Cell cycle
• ISSN: 1874-9399; 1876-4320; 1876-4320
• DOI: 10.1016/j.bbagrm.2023.194943

Through regulation of DNA packaging, histone proteins are fundamental to a wide array of biological processes. A variety of post-translational modifications (PTMs), including acetylation, constitute a proposed histone code that is interpreted by “reader” proteins to modulate chromatin structure. Canonical histones can be replaced with variant versions that add an additional layer of regulatory complexity. The protozoan parasite Toxoplasma gondii is unique among eukaryotes in possessing a novel variant of H2B designated H2B.Z. The combination of PTMs and the use of histone variants are important for gene regulation in T. gondii, offering new targets for drug development. In this work, T. gondii parasites were generated in which the 5 N-terminal acetylatable lysines in H2B.Z were mutated to either alanine (c-Myc-A) or arginine (c-Myc-R). The c-Myc-A mutant displayed no phenotype over than a mild defect in its ability to kill mice. The c-Myc-R mutant presented an impaired ability to grow and an increase in differentiation to latent bradyzoites. The c-Myc-R mutant was also more sensitive to DNA damage, displayed no virulence in mice, and provided protective immunity against future infection. While nucleosome composition was unaltered, key genes were abnormally expressed during in vitro bradyzoite differentiation. Our results show that regulation of the N-terminal positive charge patch of H2B.Z is important for these processes. We also show that acetylated N-terminal H2B.Z interacts with some unique proteins compared to its unacetylated counterpart; the acetylated peptide pulled down proteins associated with chromosome maintenance/segregation and cell cycle, suggesting a link between H2B.Z acetylation status and mitosis. •Toxoplasma gondii variant histone H2B.Z N-tail has 5 acetylatable lysines.•We generated mutants where lysines were replaced by alanines or arginines (+ patch).•Positive patch affects growth, differentiation, DNA damage response and virulence.•Pull down with acetylated and non-acetylated peptides retrieved specific interactors.•H2B.Z acetylation regulates a positive charge patch important for parasite fitness.