Biology subjects

Ausin, I.

Publications and source records attributed to Ausin, I..

3 recordsLinked to original sources

bioRxiv2024

The H3K4me3 binding ALFIN-LIKE proteins recruit SWR1 for gene-body deposition of H2A.Z

The H2A.Z histone variant is highly enriched over gene bodies, playing an essential role in several genome-templated processes, including transcriptional regulation and epigenetic patterning across eukaryotes. The SWR1 chromatin remodeling complex deposits H2A.Z. How SWR1 is directed to gene bodies is largely unknown. Here, we show that ALFIN-LIKE (AL) proteins are responsible for H2A.Z gene body patterning in Arabidopsis. AL proteins encode H3K4me3-binding PHD domains, and by ChIP-seq, we confirm preferential binding of AL5 to H3K4me3 over H3K4me1/2 in planta. We observe a global reduction in H2A.Z in al septuple mutants (al7m), especially of over H3K4me3-enriched genic regions. While MBD9 recruits SWR1 to nucleosome-free regions, ALs act non-redundantly with MBD9 for deposition of H2A.Z. Notably, al7m mutants show severe developmental abnormalities and upregulation of H2A.Z gene body-enriched responsive genes. Therefore, we propose a model whereby AL proteins direct gene body enrichment of H2A.Z by recruiting SWR1 to H3K4me3-containing responsive genes.

plant biology↗

bioRxiv2022

Histone chaperone ASF1 mediates H3.3-H4 deposition in Arabidopsis

Histone chaperones and chromatin remodelers control nucleosome dynamics, which are essential for transcription, replication, and DNA repair. The histone chaperone Anti-Silencing Factor 1 (ASF1) plays a central role in facilitating CAF-1-mediated replication-dependent H3.1 deposition and HIRA-mediated replication-independent H3.3 deposition in yeast and metazoans. Whether ASF1 function is evolutionarily conserved in plants is unknown. Here, we show that Arabidopsis ASF1 proteins display a preference for the HIRA complex. Simultaneous mutation of both Arabidopsis ASF1 genes caused a decrease in chromatin density and ectopic H3.1 occupancy at loci typically enriched with H3.3. Genetic, transcriptomic, and proteomic data indicate that ASF1 proteins strongly prefers the HIRA complex over CAF-1. asf1 mutants also displayed an increase in spurious Pol II transcriptional initiation and showed defects in the maintenance of gene body CG DNA methylation and in the distribution of histone modifications. Furthermore, ectopic targeting of ASF1 caused excessive histone deposition, less accessible chromatin, and gene silencing. These findings reveal the importance of ASF1-mediated histone deposition for proper epigenetic regulation of the genome.

plant biology↗

bioRxiv2019

Arabidopsis SWR1-associated protein methyl-CpG-binding domain 9 is required for histone H2A.Z deposition.

Deposition of the histone variant H2A.Z by the SWI2/SNF2-Related 1 chromatin remodeling complex (SWR1-C) is important for gene regulation in eukaryotes, but the composition of the Arabidopsis SWR1-C has not been thoroughly characterized. Here identify interacting partners of a conserved Arabidopsis SWR1 subunit, ACTIN-RELATED PROTEIN 6 (ARP6). We isolated nine predicted components, and identified additional interactors implicated in histone acetylation and chromatin biology. One of the novel interacting partners, methyl-CpG-binding domain 9 (MBD9), also strongly interacted with the Imitation SWItch (ISWI) chromatin remodeling complex. MBD9 was required for deposition of H2A.Z at a distinct subset of ARP6-dependent loci. MBD9 was preferentially bound to nucleosome-depleted regions at the 5 ends of genes containing high levels of activating histone marks. These data suggest that MBD9 is a SWR1-C interacting protein required for H2A.Z deposition at a subset of actively transcribing genes.

molecular biology↗