Biology subjects

Jendruchova, K.

Publications and source records attributed to Jendruchova, K..

4 recordsLinked to original sources

bioRxiv2026

Yeast Rai1p and the RAC complex (Ssz1p/Zuo1p) modulate uORF-mediated GCN4 translational control under stress conditions.

Translation reinitiation (REI) is one of the most important gene-specific regulatory mechanisms by which eukaryotic cells influence expression of main translons, for example during highly conserved integrated stress response (ISR). In S. cerevisiae, expression of the key stress response gene, GCN4, is controlled by an intricate interplay among four short upstream translons (uTranslons, formerly uORFs), resulting in high or low levels of REI at GCN4 depending on the growth conditions. Under nutrient rich conditions, GCN4 expression is repressed, but upon amino acid starvation, it is derepressed, despite of a general translational shut down. Capitalizing on our screening reporter system, we identified three new factors influencing efficiency of REI after translation of GCN4 uTranslons: Rai1p (an RNA quality control and processing factor), and Ssz1p and Zuo1p (members of the Ribosome Associated Complex [RAC]). Importantly, we showed that depletion of these factors deregulated derepression of Gcn4p synthesis under starvation. Furthermore, we found that similar to RAC, Rai1p associates with 40S subunits and actively translating ribosomes. We also explored interactomes of these proteins. Collectively, we present three previously unknown factors that co-regulate stress response to amino acid starvation in the budding yeast by unique mechanisms.

genetics↗

bioRxiv2023

Stem-loop induced ribosome queuing in the uORF2/ATF4 overlap fine-tunes stress-induced human ATF4 translational control

ATF4 is a master transcriptional regulator of the integrated stress response leading cells towards adaptation or death. ATF4s induction under stress was thought to be mostly due to delayed translation reinitiation, where the reinitiation-permissive uORF1 plays a key role. Accumulating evidence challenging this mechanism as the sole source of ATF4 translation control prompted us to investigate additional regulatory routes. We identified a highly conserved stem-loop in the uORF2/ATF4 overlap, immediately preceded by a near-cognate CUG, which introduces another layer of regulation in the form of ribosome queuing. These elements explain how the inhibitory uORF2 can be translated under stress, confirming prior observations, but contradicting the original regulatory model. We also identified two highly conserved, potentially modified adenines performing antagonistic roles. Finally, we demonstrate that the canonical ATF4 translation start site is substantially leaky-scanned. Thus, ATF4s translational control is more complex than originally described underpinning its key role in diverse biological processes.

molecular biology↗

bioRxiv2019

The 9aaTAD activation domains in the four Yamanaka Oct4, Sox2, Myc, and Klf4 transcription factors essential during the stem cell development

Somatic cells can be reprogrammed by the Yamanaka factors Oct4, Sox2, Myc and Klf4 activators into induced pluripotent stem cells. Throughout their genome, the Oct4, Sox2 and Klf4 cooperate with mediators of transcription, where the DNA binding sites serve as scaffolds for the phase-separated transcriptional condensates at distinct genome loci. In this study, we identified the 9aaTAD activation domains as the common interaction interface of the Yamanaka factors for transcription machinery. All four activation domains were identified by our online 9aaTAD prediction service and experimentally confirmed as strong activators of transcription. We considered the mediator interactions granted by 9aaTADs as part of the Yamanaka factors ability to reprogram cell fate. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=64 SRC="FIGDIR/small/876706v1_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@c5105forg.highwire.dtl.DTLVardef@1b5e910org.highwire.dtl.DTLVardef@1d83c2aorg.highwire.dtl.DTLVardef@1561881_HPS_FORMAT_FIGEXP M_FIG C_FIG

genetics↗

bioRxiv2019

The evolution of the 9aaTAD domain in Sp2 proteins: inactivation with valines and intron reservoirs

The Sp1 transcription factor has been defined as glutamine-rich activator. The Nine amino acid TransActivation Domains (9aaTAD) have been identified in numerous transcription activators. Here, we identified the conserved 9aaTAD motif in the Sp1 and in all nine members of SP family with broad natural 9aaTAD variations. We showed by the amino acid substitutions that the glutamine residues are completely dispensable for 9aaTADs function. We described the 9aaTAD domains origin and evolutionary history. The ancestral Sp2 gene with inactive 9aaTAD has duplicated in early chordates and created new paralogs Sp1, Sp3 and Sp4. We discovered that the accumulation of valines in the 9aaTADs correlated with the domain inactivation. The Sp2 activation domain, whose dormancy have lasted over 100 million years during chordate evolution, enabled later diversification in the Sp1-4 clade, including both repressors and activators. The new paralogs Sp1 and Sp3 activation domains have regained their original activator function by loss of valines in their 9aaTADs.

molecular biology↗