Characterization of subtelomeric regions and associated genes of Toxoplasma gondii.

SUSANA M CONTRERAS; ELÍAS M RIVERA; LAURA KAMENETZKY; JOSEFINA OCAMPO; LAURA VANAGAS; SERGIO O ANGEL

Woods Hole

Congreso; Molecular Parasitology Meeting XXXII; 2021

Molecular Parasitology Meetings

Toxoplasma gondii telomere-associated regions (TAS) were defined at chromosome ends based on the enrichment of H2A.X, the presence of satellite DNA, gene-free regions, and the presence of genes from the FamB and FamC subtelomeric families. In addition to the enrichment of histone H2A.X, almost all chromosomes showed peaks of the active promoter label H3K4me3 bordering the telomeric TTTAGGG sequence. The length of the TgTAS regions ranges from 14 to 233 Kbp, predominantly including sat350 satellite DNA, and including single copy genes in addition to FamB and FamC. The FamB is also represented in Neospora caninum (4), Hamondia hammondi (7) and T. gondii (15). FamC is also represented in N. caninum (3), H. hammondi (4) and T. gondii (14), suggesting an expansion from its ancestral version. FamB and FamC genes code for integral membrane proteins and have conserved and variable regions. They present a general model of one exon, although there are genes with several short exons that would code for the highly variable C-terminal region. However, phylogenetical analysis suggests that FamB and FamC genes are not evolutionarily related. Only 7 out of 15 FamB genes and 10 out of 14 FamC genes show evidence of transcription in Toxodb. The expression of these genes was confirmed by RT-PCR. Only Tsf8 (FamC) has proteomic evidence in toxodb. Antibodies against the protein rTsf8 detect a 49-kDa band in T. gondii lysate by WB, and a putative apical labeling by IFA. rTsf8 reacted poorly with serum from T. gondii-infected individuals.Toxoplasma gondii telomere-associated regions (TAS) were redefined at chromosome ends based on the enrichment of H2A.X, the presence of satellite DNA, gene-free regions, and the presence of genes from the FamB and FamC subtelomeric families. In addition to the enrichment of histone H2A.X, almost all chromosomes showed peaks of the active promoter label H3K4me3 bordering the telomeric TTTAGGG sequence. The length of the TgTAS regions ranges from 14 to 233 Kbp. Predominantly including sat350 satellite DNA and including single-copy genes in addition to FamB and FamC. The FamB is also present in Neospora caninum (4), Hamondia hammondi (7), and T. gondii (15). FamC is also represented in N. caninum (3), H. hammondi (4), and T. gondii (14), suggesting an expansion from its ancestral version. FamB and FamC genes code for integral membrane proteins and have conserved and variable regions. These genes present a general model of one exon, and some of them have several short exons that would code for the highly variable C-terminal region. However, phylogenetical analysis suggests that FamB and FamC genes are not evolutionarily related. Only 7 out of 15 FamB genes and 10 out of 14 FamC genes show evidence of transcription in Toxodb. We confirmed by RT-PCR the transcriptional expression status of these genes. Only Tsf8 (FamC) has proteomic evidence in Toxodb. Antibodies against the protein rTsf8 detect by a 49-kDa band in T. gondii in WB lysate and putative apical labeling by IFA. rTsf8 reacted poorly with serum from T. gondii-infected individuals.