bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.09.10.612373

Screening of histone mutants reveals a domain within the N-terminal tail of histone H3 that regulates the Tup1-independent repressive role of Cyc8 at the active FLO1

Singh, R.·Tomar, R. S.
View original source ↗Export metadata ↓

Abstract

Yeast flocculation relies on cell surface flocculin proteins encoded by the FLO1 gene. The expression of FLO1 is antagonistically regulated by the Tup1-Cyc8 and the Swi-Snf complexes. The Post translational modifications of core histones regulate the transcription of Tup1-Cyc8-regulated genes. However, the mechanisms by which the physical presence of tail residues regulate FLO1 transcription process and flocculation is yet to be completely understood. Through screening we have identified a new region within the N-terminal tail of histone H3 regulating the transcription of FLO1 and FLO5. One of the histone H3 N-terminal truncation mutants H3{Delta}(17-24) showed higher FLO1 expression compared to wild-type H3. Results revealed that in absence of 17-24 stretch the occupancy of Cyc8 decreases from the upstream regions of FLO1. Additionally, analysis suggests that Hda1 is required for the Cyc8-mediated repression of FLO1. Altogether we demonstrate that 17-24 stretch is essential for the Tup1 independent binding of Cyc8 at the promoters assisted by Hda1, leading to the strong repression of FLO1 transcription. In the absence of the 17-24 stretch, Cyc8 cannot bind, resulting in uncontrolled transcription of FLO1.

Explore related subjects

molecular biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Singh, R., Tomar, R. S.. 2024-09-12. Screening of histone mutants reveals a domain within the N-terminal tail of histone H3 that regulates the Tup1-independent repressive role of Cyc8 at the active FLO1. https://doi.org/10.1101/2024.09.10.612373

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Dietary selenium deficiency drives sex-specific circadian disturbance through redox imbalance and causes early systolic dysfunction in mice

Background: Selenium is a vital trace element involved in antioxidant defence and cardiovascular health. Although selenium deficiency is implicated in cardiomyopathies, its early cardiac effects and underlying mechanisms remain poorly defined. Methods: C57BL6/Njr mice were fed either a selenium deficient or control diet for 12 weeks. Systemic selenium status, cardiac function by echocardiography, left ventricular (LV) transcriptomic profiles, redox balance, and circadian pathway markers were assessed, including sex-specific analyses. Results: Selenium deficiency reduced plasma selenium levels without inducing overt cardiac hypertrophy or fibrosis. Echocardiography showed preserved ejection fraction and fractional shortening but reduced global longitudinal strain, indicating early systolic dysfunction. Cardiac stress markers were increased predominantly in male mice. Left ventricular RNA sequencing revealed enrichment of pathways related to cardiac remodelling, redox regulation, mitochondrial function, and circadian rhythm. Additional protein and metabolic analyses supported sex-specific redox circadian alterations, with males showing a more pronounced stress response profile. Conclusions: Dietary selenium deficiency induces early myocardial dysfunction and molecular remodelling before overt cardiac failure. These changes are associated with redox and circadian pathway disruption and show sex specific features, suggesting that selenium contributes to cardiac homeostasis through sex dependent redox circadian regulation.

molecular biology↗
bioRxiv2026

Dysregulation of FMR1 Splicing in Human Fragile X Syndrome

Fragile X Syndrome (FXS) is a neuro-developmental disorder caused by a CGG expansion in FMR1, leading to transcriptional silencing and loss of the encoded protein FMRP. Surprisingly, ~70% of FXS individuals express FMR1, but the RNA is mis-spliced to isoform FMR1-217, composed of exon 1 spliced to a pseudo-exon in intron 1 and cannot produce FMRP. Splice-switching ASOs rescue proper FMR1 splicing and restore FMRP. FMR1-217 mis-splicing increases with CGG repeat length and is negatively correlated with patient IQ. FMR1-217 is associated with ribosome footprints, indicating it is translated into a polypeptide that may impair cognition. R-loops form at the FMR1 locus and extend into the pseudo-exon, but splice-switching ASOs reduce FMR1-217 and elevate FMRP independently of R-loop formation. DRB-based transcription analysis identified impaired Pol II elongation at the 5 prime region of FMR1 in FXS cells, indicated by accumulation of hypophosphorylated Pol II at the transcription start site. Consistent with this, camptothecin-induced Pol II stalling increased FMR1-217 pseudo-exon inclusion. The splicing factors PTBP1 and PTBP2 regulate FMR1-217 splicing in a differentiation stage-dependent manner. Together, these findings indicate that FMR1-217 mis-splicing in FXS is associated with CGG repeat expansion, R-loop formation, impaired co-transcriptional Pol II elongation and context-dependent regulation by PTBP1/PTBP2.

molecular biology↗
bioRxiv2026

Hidden Biodiversity in Wildlife Trade Networks: DNA Barcoding Reveals Fish and Crocodilian Species in Commercialized Swim Bladders

International wildlife trade represents one of the major drivers of biodiversity exploitation worldwide. However, the true taxonomic diversity embedded within commercial wildlife products often remains unknown because processing removes diagnostic morphological characteristics, preventing reliable species identification. Consequently, biodiversity assessments based solely on product labels may substantially underestimate the diversity of species involved in trade networks. To investigate hidden biodiversity within wildlife trade products, we applied DNA barcoding based on the mitochondrial cytochrome c oxidase subunit I (COI) gene to 77 products commercialized as fish swim bladders and seized at Guarulhos International Airport, Brazil. Molecular analyses successfully identified all samples and revealed the presence of four species: Plagioscion auratus (n = 38), Cynoscion acoupa (n = 7), Melanosuchus niger (n = 17), and Caiman crocodilus (n = 15). Fish species accounted for 71.4% of all samples, whereas crocodilians represented 28.6%, demonstrating that products marketed under a single commercial category may conceal substantial taxonomic diversity. Notably, the occurrence of two Amazonian crocodilian species within a trade chain traditionally associated with fish products reveals a previously undocumented component of the international wildlife trade. Our findings demonstrate that DNA barcoding is an effective tool for uncovering hidden biodiversity within processed wildlife products and provide evidence that wildlife trade networks may involve a broader spectrum of species than suggested by commercial labels. These results highlight the importance of molecular surveillance for biodiversity monitoring, wildlife trade regulation, and conservation planning.

molecular biology↗