Biology subjects

Panek, J.

Publications and source records attributed to Panek, J..

8 recordsLinked to original sources

bioRxiv2026

Integrating suboptimal secondary structures, AI-assisted genomic synteny, and evolutionary conservation to identify bacterial ncRNA homologs beyond sequence similarity

A bioinformatic approach for genome-wide identification of homologs of bacterial non-coding RNAs (ncRNAs) integrating structural similarity, genomic synteny, and evolutionary conservation is presented. The structural similarity is detected using an algorithm for genome-wide identification of loci in genomic intergenic regions (IGRs) containing sequences capable of adopting secondary structures similar to that of the query ncRNA. The algorithm scans IGR sequences using a sliding window with a predefined step. For each window, suboptimal secondary structures are predicted and compared with the template structure to compute structural similarity scores. These scores are evaluated statistically on a genome-wide scale to infer homology of the RNAs represented by the predicted structures. Loci encoding statistically significant structures are further filtered using genomic synteny of the query ncRNAs inferred from genomic annotations. ChatGPT was used to assist in identifying literature-supported biological relationships between genes with distinct functional annotations. Syntenic loci with the structures are then examined for homologs in related species, as evolutionary conservation among related species is a common feature of ncRNAs Using this approach, we predicted novel homologs of the spot42 RNA-encoding spf gene in Glaciecola and Pseudoalteromonas genomes, and ms1 RNA genes in Frankia and Bifidobacterium genomes, where previous homology searches had failed. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=44 SRC="FIGDIR/small/737749v1_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@dd18baorg.highwire.dtl.DTLVardef@18261eforg.highwire.dtl.DTLVardef@eb95c3org.highwire.dtl.DTLVardef@b535ad_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

bioRxiv2025

Activation of pro-survival autophagy by a small molecule promoting p62 oligomerisation

Autophagy is a critical mechanism of cellular quality control, orchestrated by selective autophagy receptor (SAR) proteins. Pharmacologically enhancing the cargo-targeting capacity of SARs presents an attractive but underexplored strategy for the precise therapeutic activation of autophagy. Here, we characterise SQ-1, a small-molecule activator of autophagy that targets the prototypical SAR protein p62/SQSTM1 (sequestosome-1). We show that SQ-1 sensitises p62 to oxidation and promotes its disulphide-mediated oligomerisation in response to mitochondrial reactive oxygen species (ROS). This ROS-dependent activation of p62-mediated selective autophagy enhances the clearance of ROS-generating mitochondria and restores cell viability in models of Niemann-Pick type C1 (NPC1) disease, which is marked by impaired autophagic flux. In summary, the unique mode of action of SQ-1 enables self-regulated autophagy activation, offering a potential therapeutic strategy for lysosomal storage disorders and a broader spectrum of age-related diseases characterised by defective autophagy.

cell biology↗

bioRxiv2025

Pilidium lythri: A Climate-Driven Disruptor of Plant-Associated Microbiomes and Ecological Stability

While global warming accelerates phytopathogen spread, still little is known on how fungal pathogens disrupt fragile balance in plant-microbe interactions. Here, we demonstrate that the thermotolerant fungus Pilidium lythri combines broad chemical resistance with a remarkable ability to destabilize microbial communities in strawberry soil-plant systems. Using high-throughput sequencing (16S rRNA and ITS markers) across 72 samples, combined with mixed-effects modelling, source-tracking, microbiota assembly mechanisms investigation and network analysis we demonstrate that P. lythri disrupted bacterial community assembly processes, transitioning from deterministic to stochastic dynamics in the bulk soil, aligning with the Anna Karenina Principle. Despite stable dominance index (ENS) under infection bacterial and fungal communities, rhizosphere fungal diversity increased under infection. Network analysis of this niche revealed decreased fungal connectivity, with enhanced antagonistic interactions between taxa. We also noted that microbial migration patterns between niches under pathogen inoculation highlighted shifts in community interactions. Our work uncovers how emerging thermotolerant fungal phytopathogens destabilize plant holobiont without reducing diversity, important for managing emerging agricultural threats in a warming climate.

microbiology↗

bioRxiv2022

Mammalian intestinal intracellular Microsporidia subvert host cell autophagy to promote replication

Intracellular pathogens such as Microsporidia can interact with host proteostasis pathways such as autophagy. Previous work done in Caenorhabditis elegans demonstrated involvement of autophagy in controlling Microsporidian proliferation through ubiquitin labelling of the parasite and subsequent degradation by autolysomes. However, it remains unknown if such mechanisms also play the role in mammalian models. Here we used immunochemistry assays, super-resolution fluorescence microscopy, and modulation of the hosts autophagy flux through siRNA silencing and chemical agents to elucidate how Microsporidia interact with host mammalian cell autophagy flux. We show that despite targeting by early autophagy markers (ubiquitin and p62); the host cell was not able to complete autophagy-mediated removal of Encephalitozoon cuniculi. Furthermore, instead of helping to control Microsporidia proliferation, the induction of autophagy dramatically increased proliferation of two Microsporidian species in two different mammalian cell models. Finally, we showed that the reduction of the autophagy flux using siRNA treatment or gut microbiota-derived metabolites known to be important for the intestinal epithelium homeostasis was able to reduce the parasite proliferation. Taken together, our results indicate that Microsporidia infecting mammalian cells not only developed strategies to evade the host autophagy but also evolved way to divert the autophagy flux to promote their own growth.

microbiology↗

bioRxiv2021

'Lose-to-gain' adaptation to genome decayin the structure of the smallest eukaryotic ribosomes

AO_SCPLOWBSTRACTC_SCPLOWThe evolution of microbial parasites involves the interplay of two opposing forces. On the one hand, the pressure to survive drives parasites to improve through Darwinian natural selection. On the other, frequent genetic drifts result in genome decay, an evolutionary process in which an ever-increasing burden of deleterious mutations leads to gene loss and gradual genome reduction. Here, seeking to understand how this interplay occurs at the scale of individual macromolecules, we describe cryo-EM and evolutionary analyses of ribosomes from Encephalitozoon cuniculi, a eukaryote with one of the most reduced genomes in nature. We show that E. cuniculi ribosomes, the smallest eukaryotic cytoplasmic ribosomes to be structurally characterized, employ unparalleled structural innovations that allow extreme rRNA reduction without loss of ribosome integrity. These innovations include the evolution of previously unknown rRNA features such as molten rRNA linkers and bulgeless rRNA. Furthermore, we show that E. cuniculi ribosomes withstand the loss of rRNA and protein segments by evolving a unique ability to effectively trap small molecules and use them as ribosomal building-blocks and structural mimics of degenerated rRNA and protein segments. Overall, our work reveals a recurrent evolutionary pattern, which we term "lose-to-gain" evolution, where it is only through the loss of rRNA and protein segments that E. cuniculi ribosomes evolve their major innovations. Our study shows that the molecular structures of intracellular parasites long viewed as reduced, degenerated, and suffering from various debilitating mutations instead possess an array of systematically overlooked and extraordinary structural features. These features allow them to not only adapt to molecular reduction but evolve new activities that parasites can possibly use to their advantage.

evolutionary biology↗

bioRxiv2019

A newly defined cullin-RING ubiquitin ligase promotes thermotolerance as part of the Intracellular Pathogen Response in C. elegans

Intracellular pathogen infection leads to proteotoxic stress in host organisms. Previously we described a physiological program in the nematode C. elegans called the Intracellular Pathogen Response (IPR), which promotes resistance to proteotoxic stress and appears to be distinct from canonical proteostasis pathways. The IPR is controlled by PALS-22 and PALS-25, proteins of unknown biochemical function, which regulate expression of genes induced by natural intracellular pathogens. We previously showed that PALS-22 and PALS-25 regulate the mRNA expression of the predicted ubiquitin ligase component cullin cul-6, which promotes thermotolerance in pals-22 mutants. However, it was unclear whether CUL-6 acted alone, or together with other ubiquitin ligase components. Here we use co-immunoprecipitation studies paired with genetic analysis to define the cullin-RING ligase components that act together with CUL-6 to promote thermotolerance. First, we identify a previously uncharacterized RING domain protein in the TRIM family we named RCS-1, which acts as a core component with CUL-6 to promote thermotolerance. Next, we show that the Skp-related proteins SKR-3, SKR-4 and SKR-5 act redundantly to promote thermotolerance with CUL-6. Finally, we screened F-box proteins that co-immunoprecipitate with CUL-6 and find that FBXA-158 promotes thermotolerance. In summary, we have defined the three core components and an F-box adaptor of a cullin-RING ligase complex that promotes thermotolerance as part of the IPR in C. elegans, which adds to our understanding of how organisms cope with proteotoxic stress.\n\nSignificance StatementIntracellular pathogen infection in the nematode Caenorhabditis elegans induces a robust transcriptional response as the host copes with infection. This response program includes several ubiquitin ligase components that are predicted to function in protein quality control. In this study, we show that these infection-induced ubiquitin ligase components form a protein complex that promotes increased tolerance of acute heat stress, an indicator of improved protein homeostasis capacity. These findings show that maintaining protein homeostasis may be a critical component of a multifaceted approach allowing the host to deal with stress caused by intracellular infection.

biochemistry↗

bioRxiv2017

An algorithm for template-based prediction of secondary structures of individual RNA sequences

While understanding the structure of RNA molecules is vital for deciphering their functions, determining RNA structures experimentally is exceptionally hard. At the same time, extant approaches to computational RNA structure prediction have limited applicability and reliability. In this paper we provide a method to solve a simpler yet still biologically relevant problem: prediction of secondary RNA structure using structure of different molecules as a template.\n\nOur method identifies conserved and unconserved subsequences within an RNA molecule. For conserved subsequences, the template structure is directly transferred into the generated structure and combined with de-novo predicted structure for the unconserved subsequences with low evolutionary conservation. The method also determines, when the generated structure is unreliable.\n\nThe method is validated using experimentally identified structures. The accuracy of the method exceeds that of classical prediction algorithms and constrained prediction methods. This is demonstrated by comparison using large number of heterogeneous RNAs. The presented method is fast and robust, and useful for various applications requiring knowledge of secondary structures of individual RNA sequences.

bioinformatics↗

bioRxiv2017

An Intracellular Pathogen Response Pathway Promotes Proteostasis In C. elegans

Maintenance of proteostasis is critical for organismal health. Here we describe a novel pathway that promotes proteostasis, identified through the analysis of C. elegans genes upregulated by intracellular infection. We named this distinct transcriptional signature the Intracellular Pathogen Response (IPR), and it includes upregulation of several predicted ubiquitin ligase complex components such as the cullin cul-6. Through a forward genetic screen we found pals-22, a gene of previously unknown function, to be a repressor of the cul-6/Cullin gene and other IPR gene expression. Interestingly, pals-22 mutants have increased thermotolerance and reduced levels of stress-induced polyglutamine aggregates, likely due to upregulated IPR expression. We found the enhanced stress resistance of pals-22 mutants to be dependent on cul-6, suggesting that pals-22 mutants have increased activity of a CUL-6/Cullin-containing ubiquitin ligase complex. pals-22 mutant phenotypes are distinct from the well-studied heat shock and insulin signaling pathways, indicating that the IPR is a novel pathway that protects animals from proteotoxic stress.

genetics↗