Biology subjects

Tollec, A.

Publications and source records attributed to Tollec, A..

3 recordsLinked to original sources

bioRxiv2025

Elucidating the interaction network of one of the largest icosahedral capsids in the virosphere

Giant viruses challenge traditional boundaries of virology with their large particle sizes, complex genomes, and unique replication strategies. Yet, despite its 750 nm diameter and incorporation of dozens of proteins, mimivirus virion retains an icosahedral symmetry, a trait often associated with smaller viruses. The functional roles and interactions of most proteins composing such complex icosahedral particles remain elusive. Here, we dissect the spatial and functional organization of mimivirus morphogenesis by integrating bioinformatics, genetics and interactomics. We performed protein clustering using a structure-informed approach integrating AlphaFold models with sequence information to classify and functionally annotate the ORFan-rich mimivirus proteome. To map the protein-protein interaction network during morphogenesis, we employed endogenous tagging and co-immunoprecipitation coupled to mass spectrometry. This strategy revealed distinct interaction modules associated with the virion membrane, nucleoid and viral factory compartments. Comparative analyses with other icosahedral and non-icosahedral giant viruses uncovered conserved assembly nodes and virion shape-specific adaptations. Our findings shed light on the global organization of mimivirus virion biogenesis and highlight the evolutionary plasticity of viral morphogenetic networks within the Nucleocytoviricota.

microbiology↗

bioRxiv2025

DNA-protein interactions in Meloidogyne incognita

BackgroundThe root-knot nematode Meloidogyne incognita, is a highly destructive parasite that manipulates host plant processes through effector proteins, affecting agriculture globally. Despite advances in genomic and transcriptomic studies, the regulatory mechanisms controlling effector gene expression, especially at the chromatin level, are still poorly understood. Gene regulation studies in plant-parasitic nematodes (PPN) face several challenges, including the absence of transformation systems and technical barriers in chromatin preparation, particularly for transcription factors (TFs) expressed in secretory gland cells. Conventional methods like Chromatin Immunoprecipitation (ChIP) are limited in PPN due to low chromatin yields, the impermeability of nematode cuticles, and difficulties in producing antibodies for low-abundance TFs. These issues call for alternative approaches, such as dCas9-based CAPTURE (CRISPR Affinity Purification in siTU of Regulatory Elements) that allows studying chromatin interactions by using a catalytically inactive dCas9 protein to target specific genomic loci without relying on antibodies. ResultsThis study presents an optimized in vitro dCas9-based CAPTURE for M. incognita that addresses key challenges in chromatin extraction and stability. The protocol focuses on the promoter region of the effector gene 6F06, a critical gene for parasitism. Several optimizations were made, including improvements in nematode disruption, chromatin extraction, and protein-DNA complex stability. This method successfully isolated chromatin-protein complexes and identified four putative chromatin-associated proteins, including BANF1, linked to chromatin remodelling complexes like SWI/SNF. ConclusionThe optimized in vitro dCas9-based CAPTURE protocol offers a new tool for investigating chromatin dynamics and regulatory proteins in non-transformable nematodes. This method expands the scope of effector gene regulation research and provides new insights into parasitism in M. incognita. Future research will aim to validate these regulatory proteins and extend the method to other effector loci, potentially guiding the development of novel nematode control strategies.

molecular biology↗

bioRxiv2024

Diurnal regulation of Acyl-CoA synthetase 3 (ACSF3) underlies daily mitochondrial lysine-malonylation and hepatic metabolism

Circadian rhythms are fundamental to maintaining health and are implicated in various diseases. In the liver, daily rhythms are coordinated via the interplay between feeding rhythms and the molecular circadian clock, ensuring metabolic homeostasis. Disruption of feeding rhythms can lead to circadian misalignment, contributing to metabolic disorders, yet the underlying molecular mechanisms remain unclear. Recent evidence suggests that post-translational modifications play a key role in regulating circadian functional output. In this framework, mitochondria serve as a convergence point, integrating rhythms in metabolism, feeding rhythms and the circadian clock. In the present study, we used a multi-omics approach to investigate the role of the Acyl-CoA synthetase 3 (ACSF3) in driving lysine-malonylation and in regulating daily hepatic metabolism. We found that ACSF3 expression and its mediated impact on lysine-malonylation are rhythmic and largely governed by feeding rhythms. While hepatic ACSF3 knockdown did not alter diet-induced metabolic abnormalities, our results demonstrate that ACSF3 plays a role in the diurnal regulation of liver glycogen storage, de novo lipogenesis, and triglyceride synthesis.

physiology↗