Biology subjects

Bieluszewski, T.

Publications and source records attributed to Bieluszewski, T..

4 recordsLinked to original sources

bioRxiv2026

Chromatin crosstalk between HDA19 and NuA4 sets thresholds for stress gene activation in Arabidopsis

Histone acetylation by the plant NuA4 complex promotes high expression of growth-related genes while preventing gene body H2A.Z depletion and spurious activation of stress-responsive loci. How this NuA4-dependent chromatin state is modulated by histone deacetylases (HDACs) in plants remains unclear. Here, we investigate the interplay between NuA4 and HDACs in Arabidopsis by generating a collection of HDAC loss-of-function mutants in NuA4-proficient and NuA4-deficient backgrounds. Loss of individual HDACs did not rescue the severe growth defects of the NuA4(-) mutant; instead, most combinations further aggravated the phenotype, indicating that HDACs predominantly support rather than counteract NuA4 function. Focusing on the hda19-5Atepl1ballele, we show that loss of HDA19 causes strong developmental defects and constitutive activation of biotic stress-responsive genes, but not canonical heat-response genes. 3' RNA-seq and ChIP-seq reveal that upregulated genes in hda19-5Atepl1bdisplay increased H3K9ac and H2A.Zac with largely unchanged gene-body H2A.Z, and substantially overlap with genes induced in the NuA4-null Atepl1-2 mutant and in wild-type plants exposed to elevated temperature. Integration of our datasets with published HDA19 ChIP-seq maps shows that H2A.Zac is selectively increased at HDA19-bound H2A.Z peaks in hda19-5Atepl1b, consistent with a direct role for HDA19 in H2A.Z deacetylation. However, elevated H2A.Zac is neither necessary nor sufficient for transcriptional activation, whereas changes in H3K9ac correlate strongly with gene induction. We propose that NuA4 and HDA19 cooperate to tune chromatin at stress-related loci, with H3K9 acetylation as the primary driver of transcription and H2A.Z acetylation acting as a modulatory mark that shapes stress gene responsiveness.

plant biology↗

bioRxiv2025

Linker Histones Enhance Robustness in Diurnal Transcription Dynamics.

Linker histone H1 is crucial for chromatin organization and gene expression in Arabidopsis thaliana, influencing development and stress responses. To explore its role in diurnal gene regulation, we examined H1-deficient plants and found that H1 is essential for maintaining rhythmic gene expression. Genes losing synchronization often contained NAC transcription factor binding sites, indicating H1 may affect their accessibility. Nuclear imaging revealed that H1 subtly modulates nuclear size and chromatin distribution across the photoperiod. Epigenetic analysis showed typical diurnal changes--declines in H3K4me3 and active RNA Pol II in the evening and increases in H3K27me3. In H1 mutants, these patterns persisted but with elevated H3K4me3 and RNA Pol II (Ser2P) levels at night and in the morning. These results suggest that H1 fine-tunes chromatin and transcriptional rhythms, contributing to the temporal coordination of gene activity in response to environmental and developmental signals.

plant biology↗

bioRxiv2022

Natural variation in Arabidopsis responses to Plasmodiophora brassicae reveals an essential role for RPB1

Despite the identification of clubroot resistance genes in various Brassica crops our understanding of the genetic basis of immunity to Plasmodiophora brassicae infection in the model plant Arabidopsis thaliana remains limited. To address this issue we performed a screen of 142 natural accessions and identified 11 clubroot resistant Arabidopsis lines. Genome wide association analysis identified several genetic loci significantly linked with resistance. Three genes from two of these loci were targeted for deletion by CRISPR/Cas9 mutation in resistant accessions Est-1 and Uod-1. Deletion of Resistance to Plasmodiophora brassicae 1 (RPB1) rendered both lines susceptible to the P. brassicae pathotype P1+. Further analysis of rpb1 knock-out Est-1 and Uod-1 lines showed that the RPB1 protein is required for activation of downstream defence responses, such as the expression of phytoalexin biosynthesis gene CYP71A13. RPB1 has no known functional domains or homology to previously characterised proteins. The clubroot susceptible Arabidopsis accession Col-0 lacks a functional RPB1 gene; when Col-0 is transformed with RPB1 expression driven by its native promoter it is capable of activating RPB1 expression in response to infection but this is not sufficient to confer resistance. Constitutive over-expression of RPB1 in Col-0 leads to drastically reduced growth and activation of stress-responsive genes. Furthermore, we found that transient expression of RPB1 in Nicotiana tabacum induced programmed cell death in leaves. We conclude that RPB1 is a critical component of the defence response to P. brassicae infection in Arabidopsis, acting downstream of pathogen recognition but required for the elaboration of effective resistance.

plant biology↗

bioRxiv2019

NuA4-dependent H4 acetylation is adopted to specifically control photosynthesis-related genes

NuA4, an essential histone acetyltransferase complex, is required for efficient transcription in eukaryotes. Using genome editing, genomic approaches and biochemical assays, we characterized plant homologues of two key components of this complex, EPL1 and EAF1 in Arabidopsis thaliana. Surprisingly, we found that loss of AtEPL1, which is necessary for enzymatic activity of NuA4, is not lethal. Contrary to yeast, mutants lacking AtEAF1, responsible for complex targeting, display severe pleiotropic phenotype which copies that of Atepl1. Atepl1 and Ateaf1 mutants grow slowly, contain reduced chlorophyll levels and small chloroplasts. We provide evidence that these alterations are not caused by disturbance of GLK transcription factors, the major regulators of chloroplast development. Using ChIP-seq we show that H4 acetylation levels are dramatically reduced in the chromatin of the Atepl1 mutant, while H3 acetylation remains mostly unchanged. We use our data to define NuA4-dependent genes and show that chloroplast-related genes are significantly overrepresented in this group, consistent with the pale-green phenotypes of the mutants. We propose that NuA4 was adopted in plants to control nuclear-encoded photosynthesis genes. SignificancePhotosynthesis depends on chloroplast proteins, most of which are nucleus-encoded and thus subject to control mechanisms common across eukaryotes. Here we show that NuA4, an evolutionary conserved transcriptional coactivator, is necessary for proper development of photosynthetic apparatus. Surprisingly, in contrast to yeast and metazoans, plants engineered to lack core NuA4 subunits are capable of vegetative development despite dramatic genome-wide loss of NuA4-dependent H4K5 acetylation. This chromatin perturbation seems to directly affect 350 genes which, in addition to reduced H4K5ac levels, display decreased transcript levels but no loss of transcription-related H3K9ac. A significant proportion of these genes are related to chloroplast function, particularly to translation, an intriguing parallel to the yeast NuA4s role in transcription of ribosome biogenesis-related genes.

molecular biology↗