Biology subjects

Oeffinger, M.

Publications and source records attributed to Oeffinger, M..

5 recordsLinked to original sources

bioRxiv2026

A microeukaryotic PPR-DYW protein supports multisite C- and A-deamination RNA editing

RNA editing in mitochondria is vital for many eukaryotes. In plants, mitochondrial C-to-U deamination editing is catalyzed by tens to hundreds of PPR-DYW proteins, each typically dedicated to a specific site. Where retained, PPR-DYW family expanded independently in all eukaryotic groups examined here -- except in marine microeukaryotes diplonemids, which encode a single homolog despite deaminating their mitochondrial RNA at more than 100 sites. Here we characterize this unconventional deaminase, PPRD1, from Diplonema papillatum. Native affinity pulldown of the protein identified 20 predominantly sub-stoichiometric partners, including potential RNA-binding helical-repeat proteins. Among them, the divergent PolX-like protein DAPX1 consistently and reciprocally co-purified with PPRD1 in near-equal proportions. Structural modelling suggests that DAPX1 may stabilize the deaminase catalytic domain and expand its interaction interface. Silencing either PPRD1 or DAPX1 inhibited cell growth and reduced in vivo not only C-to-U, but also A-to-I deamination across five mitochondrial RNA-editing clusters encompassing 110 sites. Together, these results support a model of PPRD1 and DAPX1 forming the core of the Diplonema deamination-editing machinery, with sub-stoichiometric partners acting as specificity factors that guide accurate RNA editing with minimal off-target effects.

molecular biology↗

bioRxiv2025

Systematic yeast two-hybrid screening identifies novel functions for SET1C/COMPASS

Set1 is the catalytic subunit of SET1C or COMPASS, which methylates histone H3K4 and serves as a scaffold for the association of seven tightly bound polypeptides. We have employed yeast two-hybrid screenings to determine the interactome of Set1 and each subunit, providing a unique resource for exploring known and novel roles of the complex. Our screenings identified a multitude of potential interactors involved in chromatin regulation, DNA replication, meiotic breaks, and Ty transposition, processes previously associated with SET1C. Consistent with Set1 being an RNA-binding protein, the screens link SET1C to multiple aspects of RNA biogenesis, including pre-mRNA splicing and polyadenylation. The results reveal that several importins are candidate interactors of Set1, along with RGG motif-containing proteins, providing insights into the mechanisms by which Set1 moves between cytoplasmic and nuclear compartments. We further reveal that reconstituted SET1C interacts with the AT hook domain of the chromatin remodeler Snf2 and methylates multiple arginines within this domain. In vivo, we report that the ARTSTRGR AT-hook motif is methylated in a Set1-dependent manner revealing new interplay between lysine and arginine methylation.

molecular biology↗

bioRxiv2024

Protein UFMylation regulates early events of ribosomal DNA double-stranded break response

The highly repetitive and transcriptionally active ribosomal DNA (rDNA) genes are exceedingly susceptible to genotoxic stress. Induction of DNA double-strand breaks (DSBs) in rDNA repeats is associated with ATM-dependent rDNA silencing and nucleolar reorganization where rDNA is segregated into nucleolar caps. However, the regulatory events underlying this response remain elusive. Here, we identify protein UFMylation as essential for rDNA damage response in human cells. We further show the only UFM1-E3-ligase UFL1 and its binding partner DDRGK1 localize to nucleolar caps upon rDNA damage, and that UFL1 loss impairs ATM activation and rDNA transcriptional silencing, leading to reduced rDNA segregation. A first-ever analysis of nuclear and nucleolar UFMylation targets in response to DSBs induction further identified key DNA repair factors including ATM, in addition to chromatin and actin network regulators. Taken together, our data provides the first evidence of an essential role for UFMylation in orchestrating rDNA DSB repair.

molecular biology↗

bioRxiv2021

Nuclear mRNA metabolism drives selective basket assembly on a subset of nuclear pores in budding yeast

To determine which transcripts should reach the cytoplasm for translation, eukaryotic cells have established mechanisms to regulate selective mRNA export through the nuclear pore complex (NPC). The nuclear basket, a substructure of the NPC protruding into the nucleoplasm, is thought to function as a stable platform where mRNA-protein complexes (mRNPs) are rearranged and undergo quality control (QC) prior to export, ensuring that only mature mRNAs reach the cytoplasm. Here, we use proteomic, genetic, live-cell, and single-molecule resolution microscopy approaches in budding yeast to demonstrate that baskets assemble only on a subset of NPCs and that basket formation is dependent on RNA polymerase II (Pol II) transcription and subsequent mRNP processing. Specifically, we observe that the cleavage and polyadenylation machinery, the poly(A)-binding protein Pab1, and pre-mRNA-leakage factor Pml39 are required for basket assembly. We further show that while all nuclear pores can bind Mlp1, baskets assemble only on a subset of nucleoplasmic NPCs, and these basket-containing pores associate a distinct protein and RNA interactome. Taken together, our data points towards nuclear pore heterogeneity and an RNA-dependent mechanism for functionalization of nuclear pores in budding yeast through nuclear basket assembly.

cell biology↗

bioRxiv2021

GFI1 tethers the NuRD complex to open and transcriptionally active chromatin in myeloid progenitors

GFI1 is a SNAG-domain, DNA binding transcriptional repressor which controls myeloid differentiation, in particular the formation of neutrophils. Here we show that GFI1 interacts with the chromodomain helicase CHD4 and other components of the "Nucleosome remodeling and deacetylase" (NuRD) complex. In granulo-monocytic precursors, GFI1, CHD4 or GFI1/CHD4 complexes occupy sites of open chromatin enriched for histone marks associated with active transcription suggesting that GFI1 recruits the NuRD complex to target genes that are regulated by active or bivalent promoters and active enhancers. Our data also show that GFI1 and GFI1/CHD4 complexes occupy promoters of different sets of genes that are either enriched for IRF1 or SPI-1 consensus sites, respectively. During neutrophil differentiation, overall chromatin closure and depletion of H3K4me2 occurs at different degrees depending on whether GFI1, CHD4 or both are present, indicating that GFI1 affects the chromatin remodeling activity of the NuRD complex. Moreover, GFI1/CHD4 complexes regulate chromatin openness and histone modifications differentially to enable regulation of target genes affecting the signaling pathways of the immune response or nucleosome organization or cellular metabolic processes.

molecular biology↗