Toxoplasma gondii chromodomain protein 1 binds to heterochromatin and colocalises with centromeres and telomeres at the nuclear periphery

Abstract

Background: Apicomplexan parasites are responsible for some of the most deadly parasitic diseases afflicting humans, including malaria and toxoplasmosis. These obligate intracellular parasites exhibit a complex life cycle and a coordinated cell cycle-dependant expression program. Their cell division is a coordinated multistep process. How this complex mechanism is organised remains poorly understood. Methods and Findings: In this study, we provide evidence for a link between heterochromatin, cell division and the compartmentalisation of the nucleus in Toxoplasma gondii. We characterised a T. gondii chromodomain containing protein (named TgChromo1) that specifically binds to heterochromatin. Using ChIP-on-chip on a genome-wide scale, we report TgChromo1 enrichment at the peri-centromeric chromatin. In addition, we demonstrate that TgChromo1 is cell-cycle regulated and co-localised with markers of the centrocone. Through the loci-specific FISH technique for T. gondii, we confirmed that TgChromo1 occupies the same nuclear localisation as the peri-centromeric sequences. Conclusion: We propose that TgChromo1 may play a role in the sequestration of chromosomes at the nuclear periphery and in the process of T. gondii cell division. © 2012 Gissot et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.