Highlights

Immunoglobulin M (IgM) are oligomeric antibodies that constitute the first line of immune defense, linking antigen recognition to the activation of inflammation. In their full-length form, activation of the complement system though binding of the initiating molecule C1q requires prior antigen engagement via Fab domains. In contrast, the contribution of their core, the constant fragment (Fc), remained poorly defined. In a study published in FEBS Journal, IBS researchers evaluated the (…)

Superbugs are drug-resistant microbes causing about 700,000 deaths annually, potentially rising to 10 million by 2050. Pseudomonas aeruginosa is a major hospital-acquired multidrug resistant pathogen, especially dangerous for immunocompromised patients. The World Health Organization lists it as a critical priority pathogen, highlighting the urgent need for new drug targets and therapies. Because of its key role in bacterial infection, the Type III Secretion System (T3SS) represents a major (…)

Microbes are amazing chemists, performing reactions to recycle biological matter, depolluting environments, and contributing to Earth´s biogeochemical cycles. Among them are anaerobic methanotrophs, microbes that consume methane in oxygen-free environments. By preventing the release of this potent greenhouse gas into the atmosphere, they play an important role in mitigating climate change. However, studying the chemical reactions that these microbes carry out is challenging: They cannot be (…)

Intrinsically disordered proteins (IDPs) play central roles in cellular signaling and regulation by mediating dynamic, context-dependent protein-protein interactions. While IDPs exist as conformational ensembles in their unbound state, they often undergo folding transitions to form structured complexes upon partner protein binding. This process is often thought to involve short linear motifs that fold in a largely cooperative, single step, however, growing evidence suggests that IDPs may (…)

Tardigrades are microscopic aquatic animals that exhibit remarkable resistance to environmental stress, including radiation, cryogenic temperatures and desiccation. Although the origins of this extremotolerance are poorly understood, intrinsically disordered proteins are known to play a crucial role, allowing tardigrades to survive in a dormant state for long periods of time (years), and to function normally upon return to ambient conditions. Researchers from the Protein Dynamics and (…)

Ten years ago, it came as a surprise that vitamin B12 derivatives have been repurposed for light detection by a large family of previously unknown photoreceptors in bacteria, which perform various functions. A prototype vitamin B12 photoreceptor, CarH, regulates the expression of genes involved in protecting bacteria from excessive sunlight. It does so by binding to DNA in the dark, acting as a molecular stopper. When exposed to light, its tetrameric architecture breaks down, enabling (…)

Chondroitin sulfate (CS) is a long, highly sulfated polysaccharide found at the cell surface and in the extracellular matrix. CS plays important roles in numerous biological processes, including cell signaling and morphogenesis. The chain elongation step, during which the long polysaccharide backbone is generated, is a critical step in CS biosynthesis. Four chondroitin sulfate synthase proteins (CHSY1, CHSY3, CHPF, and CHPF2) have been previously identified in humans. However, their (…)

Irina Gutsche, research director at the CNRS and group leader at the IBS, has been awarded the Jacques Piraud Prize by the Fondation de la Recherche Médicale (FRM) for her work in advanced electron microscopy aimed at deciphering fundamental biological mechanisms and opening up new therapeutic perspectives. To know more more about the 2025 Jacques Piraud Prize from the FRM and I. Gutsche’s research work

Rebekka Wild, CNRS research fellow and team leader at IBS, received the Paoletti Prize 2025 for her work on understanding glycosaminoglycans at the molecular level. Learn more about the 2025 Paoletti Prize and its winner.

Atmospheric nitrogen (N2) is, for the most part, an inert gas for living beings on Earth. That is, we cannot directly utilize this vital compound. Therefore, the biochemical nitrogen cycle, and especially the role played by bacteria and plants, is essential to sustaining life on our planet. In some microorganisms, a process known as biological nitrogen fixation occurs, in which nitrogenases, oxygen-sensitive proteins, transform atmospheric nitrogen into forms usable for life. To function, (…)

Researchers from the Institut de Biologie Structurale, the Max Planck Institute for Marine Microbiology, and the Max Planck Institute of Molecular Cell Biology and Genetics have unraveled a key step in the conversion of the toxic carbon monoxide into ethanol performed by the bacterium Clostridium autoethanogenum. The study, published in Nature Chemical Biology, reveals the key role of a tungsten-containing enzyme in this remarkable process, bringing new insight into the sustainable (…)

Baculoviruses are viruses that specifically infect insect cells and play a key role in regulating their populations. They are used both as biological control agents in agronomy and, most importantly, as expression systems for the production of recombinant proteins in structural biology (insect cell culture). Morphologically, Baculoviruses possess a nucleocapsid, the protein assembly that protects and packages the viral DNA, surrounded by a lipid envelope into which viral glycoproteins are (…)

In eukaryotes, U-rich small nuclear RNAs (snRNAs) are integral components of spliceosomes, the cellular machines that mediate the splicing of nascent mRNA. Before their incorporation into spliceosomal particles, snRNAs must be transiently exported to the cytoplasm, where part of their maturation takes place. Although the complex mediating snRNA nuclear export was first identified 25 years ago, the molecular details of its function and assembly have remained unclear. Scientists from the IBS (…)

While humans burn methane to generate energy to warm their homes, some gifted microbes “burn” methane without oxygen to acquire cellular energy. This process is carried out by a specific group of microbes called ANaerobic MEthanotrophic archaea (ANMEs for short), which munch on methane to spit out CO2. Why would these invisible life forms matter? Because they are prime actors in the planetary carbon cycle. In marine sediments without oxygen, ANMEs consume about 70% of methane before it is (…)

In an article published in Nature Structural and Molecular Biology, scientists describe a new structural module at the heart of bacterial energy metabolism. By combining bioinformatics approaches with cutting-edge structural biology techniques, the IBS researchers, in collaboration with the LCB (Bacterial Chemistry Laboratory, Marseille), were able to identify a new structural module: a surprising tubular structure that connects oxidoreductases to the bacterial membrane and thus to (…)

Every year the CNRS rewards the women and men, from its Joint Research Units, who have contributed most significantly to advancing French research and innovation. In 2025, two IBS engineers are honored: Alicia Vallet, a nuclear magnetic resonance study engineer in the IBS NMR group, has been awarded the 2025 CNRS Crystal Medal for her involvement in the Infranalytics national research infrastructure. Meet Alicia Contact Lionel Imbert, research engineer in the NMR Large Assemblies (…)

Cryptochromes are ubiquitous proteins, central to the regulation of the circadian clock. The majority of cryptochromes are light-sensitive and thus also serve as photoreceptors (for blue or red light). Additionally, some cryptochromes act as photoenzymes able to perform DNA damage repair while others are believed to be sensors of the earth’s magnetic field in migratory birds. Despite their ubiquitousness and the exceptional plurality of their function, the mechanisms governing the transition (…)

In response to the alarming rise in antibiotic resistance, the search for new bioactive molecules has become a public health priority. Among the most promising leads are ribosomally-synthesized and post-translationally modified peptides (RiPPs), a diverse family of natural compounds with rich structural complexity and therapeutic potential. In collaboration with a research team from Singapore and scientists from the EDyP laboratory at IRIG (CEA-Grenoble), researchers from the (…)

Photoconvertible fluorescent proteins (PCFPs) like mEos4b shift their fluorescence emission from green to red upon 405 nm illumination, making them essential markers for super-resolution techniques such as Single Molecule Localization Microscopy (SMLM). However, their photophysical properties continue to reveal surprises. Besides photoconversion, PCFPs can reversibly switch between fluorescent and nonfluorescent states. In its red form, mEos4b undergoes “negative switching”: it turns off (…)

EL222 is a light-sensitive protein from the marine bacterium Erythrobacter litoralis that regulates gene expression in response to blue light. This regulation occurs through structural changes triggered by the activation of a small molecule inside the protein, called flavin mononucleotide (FMN). To better understand how EL222 functions, the NMR group of the IBS, and researchers from the Institute of Biotechnology of the Czech Academy of Sciences, investigated chemical and structural (…)