Dataset Information

Two distinct SWI/SNF complexes direct chromatin-linked transcriptional programs in Toxoplasma

ABSTRACT: Chromatin remodeling complexes dynamically modify DNA accessibility to mediate changes in gene expression during eukaryotic cell cycle progression, developmental transitions, and environmental adaptation. Higher eukaryotes have multiple remodeler subtypes based on the incorporation of different ATPases; however, the coordination and functional specificity of these diverse complexes is not well understood. Apicomplexan parasites such as Toxoplasma gondii have a limited set of chromatin remodelers offering a divergent setting in which to explore the function of homologous complexes. These parasites have selectively retained the Myb domain–containing proteins with homology to chromatin-associated regulators like SNF2h and SWI3. Here, a comprehensive analysis of the Myb protein family in Toxoplasma defines the composition of two SWI3 complexes with mutually exclusive ATPase homologous—TgSNF2a and TgSNF2b. Integrating transcriptomics with a custom chromatin-profiling strategy, we show that TgSNF2a is essential for the timely transcription of genes, while TgSNF2b ensures global transcriptional competency and fidelity throughout the cell cycle and developmental transitions. Cell cycle–resolved chromatin profiling conclusively shows the shift from TgSNF2b to TgSNF2a occupancy when regulated genes transition from being poised to being actively transcribed. Our findings demonstrate that TgSNF2a and TgSNF2b perform distinct yet interdependent regulatory roles shaped by their chromatin context. This work uncovers ancestral principles of chromatin regulation and offers new insight into the functional diversification of SWI/SNF complexes across eukaryotes.

INSTRUMENT(S):

ORGANISM(S): Toxoplasma Gondii Gt1

TISSUE(S): Permanent Cell Line Cell

DISEASE(S): Toxoplasmosis

SUBMITTER: Dominic Schwarz

LAB HEAD: Sebastian Lourido

PROVIDER: PXD066820 | Pride | 2026-04-26

REPOSITORIES: Pride

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Dataset's files

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			Action	DRS
	20230518_Exploris_ES902_LouridoLab_DS_RH-Tir1_mNG_IP.msf	Msf
	20230518_Exploris_ES902_LouridoLab_DS_RH-Tir1_mNG_IP.mzML	Mzml
	20230518_Exploris_ES902_LouridoLab_DS_RH-Tir1_mNG_IP.mzid	Mzid
	20230518_Exploris_ES902_LouridoLab_DS_RH-Tir1_mNG_IP.raw	Raw
	20230518_Exploris_ES902_LouridoLab_DS_tgDS006_mNG_IP.raw	Raw

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Publications

Two distinct SWI/SNF complexes direct chromatin-linked transcriptional programs in <i>Toxoplasma</i>.

Schwarz Dominic D Tapia Benicio B Lourido Sebastian S

bioRxiv : the preprint server for biology 20250716

Chromatin remodeling complexes dynamically modify DNA accessibility to mediate changes in gene expression during eukaryotic cell cycle progression, developmental transitions, and environmental adaptation. Higher eukaryotes have multiple remodeler subtypes based on the incorporation of different ATPases; however, the coordination and functional specificity of these diverse complexes is not well understood. Apicomplexan parasites such as <i>Toxoplasma gondii</i> have a limited set of chromatin rem ...[more]

PMID: 40791499

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Project description:Mitosis entails global alterations to chromosome structure and nuclear architecture, concomitant with transient silencing of transcription. How cells transmit transcriptional states through mitosis remains incompletely understood. While many nuclear factors dissociate from mitotic chromosomes, the observation that certain nuclear factors and chromatin features remain associated with individual loci during mitosis originated the hypothesis that they could provide transcriptional memory through mitosis. To obtain the first genome-wide view of the dynamics of chromatin structure during mitosis, we compared the DNase sensitivity of interphase and mitotic chromatin at two stages of cellular maturation in a rapidly dividingmurine erythroblastmodel. Despite global chromosome condensation visible during mitosis at the microscopic level, the chromatin accessibility landscape is largely unaltered. However, mitotic chromatin accessibility is locally dynamic, with individual loci maintaining none, some, or all of their interphase accessibility. Mitotic reduction in accessibility occurs primarily within narrow, highly hypersensitive sites that frequently coincide with transcription factor binding sites, whereas broader domains of moderate accessibility tend to be more stable. In mitosis, proximal promoters generally maintain their accessibility, whereas distal regulatory elements preferentially lose accessibility. Promoters with the highest degree of accessibility preservation in mitosis tend to also be accessible across many murine tissues in interphase. Transcription factor GATA1 exerts site-specific changes in interphase accessibility that are most pronounced at distal regulatory elements, but does not visibly influence mitotic accessibility. We conclude that features of open chromatin are remarkably stable through mitosis and are modulated at the level of individual genes and regulatory elements. Dnase-Seq data is integrated with Chip-seq [GSE36589, GSE30142] and RNA-seq to examine epigentic changes in mitosis. We performed DNase-seq on two cell lines, G1E and G1E-ER4, both on an asynchronus population, and on a sample of cells in mitosis; each of the 4 experiments in triplicate.

Dataset Information

Two distinct SWI/SNF complexes direct chromatin-linked transcriptional programs in Toxoplasma

Dataset's files

Publications

Two distinct SWI/SNF complexes direct chromatin-linked transcriptional programs in <i>Toxoplasma</i>.

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Dataset Information

Two distinct SWI/SNF complexes direct chromatin-linked transcriptional programs in Toxoplasma

Dataset's files

Publications

Two distinct SWI/SNF complexes direct chromatin-linked transcriptional programs in &lt;i&gt;Toxoplasma&lt;/i&gt;.

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OmicsDI is part of the ELIXIR infrastructure

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Two distinct SWI/SNF complexes direct chromatin-linked transcriptional programs in <i>Toxoplasma</i>.