Biology subjects

Boggild, A.

Publications and source records attributed to Boggild, A..

3 recordsLinked to original sources

bioRxiv2026

Structural thermodynamics by cryo-EM resolves minute energy differences in heterogeneous protein complexes.

Hetero-oligomeric protein complexes play crucial roles across biology, providing combinatorial diversity and context-specific functionality in membrane receptors, molecular chaperones and beyond. Yet, existing methods are limited in their ability to resolve and quantify the assembly energetics of complex biomolecular populations. Here, we introduce a comprehensive method combining iterative 3D classification, error-rate quantification via simulated particles, and global thermodynamic modeling to extract interaction energies from cryo-EM data. Using hexameric cruciferin (the primary rapeseed storage protein) as a model, we reconstruct a 1.83 [A] structure and distinguish three highly similar 50 kDa isoforms. We resolve the complex compositional heterogeneity of the hexameric species at the single-particle level and fit a global binding model revealing pairwise interaction energies between isoforms differing by fractions of the thermal energy (kB T ). This method offers a powerful, broadly applicable tool to characterize the compositional heterogeneity and energetics of biomolecular complexes.

biophysics↗

bioRxiv2025

Structure and function of a fungal AB toxin-like chimerolectin involved in anti-nematode defense

Fungal defense against predators largely relies on protein toxins, many of which are lectins. We previously showed that the production of the nematotoxin CCTX2 is upregulated in the Agaricomycete Coprinopsis cinerea upon predation by nematodes. Here, we classify CCTX2 as the founding member of a family of fungal chimerolectins. Cryo-EM analysis to 3.2 [A] resolution reveals five domains. The four N-terminal {beta}-trefoil fold (BTF) domains cradle a C-terminal domain, which exhibits a novel +{beta} protein fold. Mutational analysis shows that both N-terminal and C-terminal domains are required for nematotoxicity. While the biochemical function of the C-terminal domain remains unclear, the first two BTF domains enable CCTX2 to bind to glycosphingolipids with LacNAc or LacdiNAc glycoepitopes on nematode intestinal epithelial cells. Experiments in the model nematode Caenorhabditis elegans demonstrate that the chimerolectin CCTX2 exploits the endocytic and retrograde trafficking machinery of the target cell to exert its toxicity and obtain access to the yet-to-be-identified intracellular target of the non-lectin domain. The structure and mode of action of CCTX2 is reminiscent of bacterial and plant AB toxins.

microbiology↗

bioRxiv2023

Comparative electric and ultrastructural studies of cable bacteria reveal new components of conduction machinery

Cable bacteria encompass at least two genera, and they are known to vary greatly in habitat preferences and filament thickness. We systematically investigated variations and similarities in cellular structures and electrical properties of different cable bacteria strains. Using SEM, TEM, STEM-EDX and ToF-SIMS, we characterized shared features of cable bacteria, such as inner and outer membranes, surface layer and cell junction architecture, as well as strain specific features, like the number and size of periplasmic conductive fibers (PCFs). Our data indicates that the PCFs are organized as loose stranded rope-like structures. With spatially resolved elemental analysis we detected nickel-containing co-factors within the PCF of cable bacteria strains in both genera suggesting a conserved conduction mechanism. Electrical conductivity of different cable bacteria strains showed a range of values covering three orders of magnitude indicating an unknown metabolic adaptation. Using cryogenic electron tomography we discovered multiple polar chemosensory arrays, abundant cytoplasmic inner membrane-attached vesicles (IMVs), polysomes and inner membrane invaginations that shed light on cable bacteria metabolism including complex motility control mechanisms, localized protein synthesis, and membrane remodeling. We propose that the IMVs discovered in this work are novel metabolic hubs closely connected to the unique conductive fiber structure of cable bacteria.

microbiology↗