Label-free Quantitative Acetylomics Revealed Toxoplasma gondii Genotype-Specific Acetylome Signatures

Distinct genotypic and pathogenicity differences exist between strains of the opportunistic protozoan Toxoplasma gondii. The label-free quantitative acetylomics approach was applied to investigate the differences in the level of acetylation between RH strain, PRU strain and PYS strain of T. gondii. The results showed that lysine acetylation in RH strain was the largest (458 acetylated proteins) among the three strains. The PYS strain had the second-largest acetylome (188 acetylated proteins), whereas lysine acetylation in PRU strain (115 acetylated proteins) was the smallest. Motif analysis revealed four, three and four motifs enriched from lysine acetylation sequences in RH strain, PRU strain and PYS strain respectively, suggesting specificity of acetyltransferases in these strains. Our analysis also identified 15 DAPs (differentially expressed acetylated proteins), 3 DAPs and 26 DAPs in RH strain vs PRU strain, PRU strain vs PYS strain and PYS strain vs RH strain, respectively. Compared with PYS strain and PRU strain, histone acetyltransferase and glycyl-tRNA synthase had higher expression levels in RH strain, reflecting genotype-specific differences in stress tolerance. These findings provide novel insight into the acetylomic profiles of major genotypes of T. gondii and provide an important resource for further analysis of the roles of the acetylated parasite proteins in the regulation of cellular functions.