Biology subjects

Baytek, G.

Publications and source records attributed to Baytek, G..

3 recordsLinked to original sources

bioRxiv2021

Implementing solid-phase-enhanced sample preparation for Co-Immunoprecipitation with Mass Spectrometry for C. elegans

Studying protein-protein interactions in vivo can reveal key molecular mechanisms of biological processes. Co-Immunoprecipitation followed by Mass Spectrometry (CoIP-MS) allows detection of protein-protein interactions in high-throughput. The nematode Caenorhabditis elegans (C. elegans) is a powerful genetic model organism for in vivo studies. Yet, its rigid cuticle and complex tissues require optimization for protein biochemistry applications to ensure robustness and reproducibility of experimental outcomes. Therefore, we optimized CoIP-MS application to C. elegans protein lysates by combining a native CoIP procedure with an efficient sample preparation method called single-pot, solid-phase-enhanced, sample preparation method (SP3). Our results based on the subunits of the conserved chromatin remodeler FACT demonstrate that our SP3-integrated CoIP-MS procedure for C. elegans samples is highly accurate and robust. Moreover, in a previous study (Baytek et al. 2021), we extended our technique to studying the chromodomain factor MRG-1 (MRG15 in human), which resulted in unprecedented findings. Method SummaryCombination of cryo-fracture with single-pot, solid-phase-enhanced, sample preparation (SP3) to perform Co-Immuno-Precipitation followed by Mass Spectrometry (CoIP-MS) provides robust assessments of protein-protein interaction using C. elegans whole animals.

biochemistry↗

bioRxiv2021

SUMOylation of the chromodomain factor MRG-1 in C. elegans affects chromatin-regulatory dynamics

Epigenetic mechanisms to control chromatin accessibility and structure is important for gene expression in eukaryotic cells. Chromatin regulation ensures proper development and cell fate specification but is also essential later in life. Modifications of histone proteins as an integral component of chromatin can promote either gene expression or repression, respectively. Proteins containing specific domains such as the chromodomain recognize mono-, di- or tri-methylated lysine residues on histone H3. The chromodomain protein MRG-1 in Caenorhabditis elegans is the ortholog of mammalian MRG15, which belongs to the MORF4 Related Gene (MRG) family in humans. In C. elegans MRG-1 predominantly binds methylated histone H3 lysine residues at position 36 (H3K36me3). MRG-1 is important during germline maturation and for safeguarding the germ cell identity. However, it lacks enzymatic activity and depends on protein-protein interaction to cooperate with other factors to regulate chromatin. To elucidate the variety of MRG-1 interaction partners we performed in-depth protein-protein interaction analysis using immunoprecipitations coupled with mass-spectrometry. Besides previously described and novel interactions with other proteins, we also detected a strong association with the Small Ubiquitin-like Modifier (SUMO). Since SUMO is known to be attached to proteins in order to modulate the target proteins activity we assessed whether MRG-1 is post-translationally modified by SUMOylation. Notably, we provide evidence that MRG-1 is indeed SUMOylated and that this post-translational modification influences the chromatin-binding profile of MRG-1 in the C. elegans genome. Our presented study hints towards an important role of SUMOylation in the context of epigenetic regulation via the chromodomain protein MRG-1, which may be a conserved phenomenon also in mammalian species.

biochemistry↗

bioRxiv2017

FACT sets a barrier for cell fate reprogramming in C. elegans and Human

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC=\"FIGDIR/small/185116_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (59K):\norg.highwire.dtl.DTLVardef@15ae7aaorg.highwire.dtl.DTLVardef@11f5c08org.highwire.dtl.DTLVardef@1d32442org.highwire.dtl.DTLVardef@f1808f_HPS_FORMAT_FIGEXP M_FIG C_FIG The chromatin regulator FACT (Facilitates Chromatin Transcription) is essential for ensuring stable gene expression by promoting transcription. In a genetic screen using C. elegans we identified that FACT maintains cell identities and acts as a barrier for transcription factor-mediated cell fate reprogramming. Strikingly, FACTs role as a reprogramming barrier is conserved in humans as we show that FACT depletion enhances reprogramming of fibroblasts into stem cells and neurons. Such activity of FACT is unexpected since known reprogramming barriers typically repress gene expression by silencing chromatin. In contrast, FACT is a positive regulator of gene expression suggesting an unprecedented link of cell fate maintenance with counteracting alternative cell identities. This notion is supported by ATAC-seq analysis showing that FACT depletion results in decreased but also increased chromatin accessibility for transcription factors. Our findings identify FACT as a cellular reprogramming barrier in C. elegans and humans, revealing an evolutionarily conserved mechanism for cell fate protection.

developmental biology↗