Christopher A. Beaudoin

Background: Freezing of gait (FOG) in Parkinson's disease is associated with abnormal beta activity in the subthalamic nucleus (STN), but the temporal structure of burst dynamics remains poorly understood. Objectives: To determine whether temporal features of STN beta bursts distinguish pre-freeze from stable gait and predict freezing onset. Methods: STN recordings during gait from four individuals were analyzed. Temporal features of burst timing, including entropy and variability, were computed across behavioral states. Predictive performance was assessed using leave-one-patient-out classifiers. Results: Entropy of inter-burst intervals was reduced prior to freezing (p < 0.01), with strong predictive performance (AUC = 0.825; threshold AUC = 0.858). During freezing, variability measures decreased and temporal structure increased, while entropy did not differ from pre-freeze. Phase-amplitude coupling showed frequency-specific but heterogeneous effects across comparisons. Conclusions: Reduced temporal variability of STN beta burst timing precedes and predicts freezing, suggesting a transition to constrained neural dynamics.

Leprosy remains a leading infectious cause of preventable disability, yet its causative agent, Mycobacterium leprae (M. leprae) , is structurally under-characterised. Only ten Protein Data Bank (PDB) entries represent seven of its 1,603 protein-coding genes. We present HANSEN, a proteome-wide structural and functional resource for M. leprae . Monomeric and oligomeric models were generated with AlphaFold 3, Boltz-1, Boltz-2 and Chai-1, and annotated with per-residue confidence, predicted aligned error and, for assemblies, interface confidence. Ligand-binding pockets were predicted with AF2BIND, P2Rank and fpocket, template-derived ligands were modelled within oligomeric complexes, residue-level B-cell epitope propensity was estimated with DiscoTope-3.0, and gene essentiality was transferred from Mycobacterium tuberculosis transposon-sequencing labels. These features are integrated in a relational database with interactive visualisation and combined into a calibrated Target Priority Score that ranks all 1,603 proteins into four tiers and recovers established antimycobacterial targets. HANSEN ( https://hansen-leprosy.medschl.cam.ac.uk/home ) provides a practical basis for target prioritisation and structure-guided drug discovery in leprosy.

Abnormal beta-band activity (13-30 Hz) within the cortico-basal ganglia network is a hallmark of Parkinson’s disease (PD) and is closely linked to motor impairment. Pathological beta activity in the subthalamic nucleus (STN) occurs predominantly as brief, high-amplitude bursts rather than continuous oscillations. Although beta-band coherence between the STN and cortex increases during bursts, it remains unclear whether cortico-STN beta coupling persists outside these bursts. Using intraoperative STN local field potentials and simultaneous cortical electrocorticography from seven patients undergoing deep brain stimulation implantation surgery, cortico-STN beta coupling during burst and non-burst epochs was compared. Coupling was assessed using magnitude-squared coherence and the debiased weighted phase lag index (dwPLI) and compared against surrogate distributions generated by circular time-shifting. Both coupling metrics were significantly elevated during burst epochs relative to non-burst periods. During non-burst epochs, coupling collapsed to surrogate levels, indicating no evidence of sustained synchronization. Time-resolved analyses further demonstrated that elevated coupling was confined to burst epochs. Although a subset of motor cortical contacts exhibited elevated baseline coherence, coupling was less evident using dwPLI. These findings suggest that pathological cortico-STN beta coupling in PD is preferentially expressed during beta bursts rather than sustained across non-burst epochs, with implications for adaptive neuromodulation strategies.

Bioelectrical signalling is fundamental for regulating biological processes in all forms of life. Ion channels and transporters generate and propagate electrical currents by selectively allowing ions to flow across membranes in response to voltage changes. Although recent breakthroughs in structural determination methods, such as cryogenic electron microscopy, have provided novel insights into the structure–function relationships of ion channels and scaffolding proteins, their precise roles in bioelectrical signal generation and propagation within and across different cells and tissues remain unresolved. This article examines the biochemical and ultrastructural features of the three most studied modes of bioelectrical conduction in human tissues—electrotonic, saltatory and ephaptic conduction—and how biophysical constraints set by membranes and proteins give rise to bioelectricity. Notably, ion channel clustering and scaffolding proteins that define intermembrane distances are common key features among all forms of bioelectrical signalling. Techniques like cryogenic electron tomography offer promising avenues for exploring ion channels and their regulatory protein interactions in situ. The central question is: ‘How does the spatial organization of ions, molecules and tissues give rise to bioelectricity?’ These insights may inform novel therapeutic approaches for various diseases, while also potentially offering new perspectives on life, evolution and consciousness.

Similarity between candidate drug targets and human proteins is commonly assessed to minimize the occurrence of side effects. Although numerous drugs have been found to disrupt the health of the human microbiome, no comprehensive comparison between established drug targets and the human microbiome metaproteome has yet been conducted. Therefore, herein, sequence and structure alignments between human and pathogen drug targets and representative human gut, oral, and vaginal microbiome metaproteomes were performed. Both human and pathogen drug targets were found to be similar in sequence, function, structure, and drug binding capacity to proteins in diverse pathogenic and non-pathogenic bacteria from all three microbiomes. The gut metaproteome was identified as particularly susceptible overall to off-target effects. Certain symptoms, such as infections and immune disorders, may be more common among drugs that non-selectively target host microbiota. These findings suggest that similarities between human microbiome metaproteomes and drug target candidates should be routinely checked.

Voltage-gated sodium channel α-subunits (NaV1.1–1.9) initiate and propagate action potentials in neurons and myocytes. The NaV β-subunits (β1–4) have been shown to modulate α-subunit properties. Homo-oligomerization of β-subunits on neighboring or opposing plasma membranes has been suggested to facilitate cis or trans interactions, respectively. The interactions between several NaV channel isoforms and β-subunits have been determined using cryogenic electron microscopy (cryo-EM). Interestingly, the NaV cryo-EM structures reveal the presence of N-linked glycosylation sites. However, only the first glycan moieties are typically resolved at each site due to the flexibility of mature glycan trees. Thus, existing cryo-EM structures may risk de-emphasizing the structural implications of glycans on the NaV channels. Herein, molecular modeling and all-atom molecular dynamics simulations were applied to investigate the conformational landscape of N-linked glycans on NaV channel surfaces. The simulations revealed that negatively charged sialic acid residues of two glycan sites may interact with voltage-sensing domains. Notably, two NaV1.5 isoform-specific glycans extensively cover the α-subunit region that, in other NaV channel α-subunit isoforms, corresponds to the binding site for the β1- (and likely β3-) subunit immunoglobulin (Ig) domain. NaV1.8 contains a unique N-linked glycosylation site that likely prevents its interaction with the β2 and β4-subunit Ig-domain. These isoform-specific glycans may have evolved to facilitate specific functional interactions, for example, by redirecting β-subunit Ig-domains outward to permit cis or trans supraclustering within specialized cellular compartments such as the cardiomyocyte perinexal space. Further experimental work is necessary to validate these predictions.

Highlights Three N-linked glycosylation sites conserved among all Nav channels Glycan modelling and molecular dynamics simulations highlight 3D landscape Unique Nav1.5 N-linked glycans may prevent binding to Ig-domains of β1 and β3 Unique Nav1.8 N-linked glycan may prevent binding to Ig-domains of β2 and β4 N-linked glycans likely contribute to supra-molecular clustering of Nav channels Voltage-gated sodium channel α-subunits (Nav1.1-1.9) initiate and propagate action potentials in neurons and myocytes. The Nav β-subunits (β1-4) have been shown to modulate α-subunit properties. Homo-oligomerization of β-subunits on neighboring or opposing plasma membranes has been suggested to facilitate cis or trans interactions, respectively. The interactions between several Nav channel isoforms and β-subunits have been determined using cryogenic electron microscopy (cryo-EM). Interestingly, the Nav cryo-EM structures reveal the presence of N-linked glycosylation sites. However, only the first glycan moieties are typically resolved at each site due to the flexibility of mature glycan trees. Thus, existing cryo-EM structures may risk de-emphasizing the structural implications of glycans on the Nav channels. Herein, molecular modelling and all-atom molecular dynamics simulations were applied to investigate the conformational landscape of N-linked glycans on Nav channel surfaces. The simulations revealed that negatively-charged sialic acid residues of two glycan sites may interact with voltage-sensing domains. Notably, two Nav1.5 isoform-specific glycans extensively cover the α-subunit region that, in other Nav channel α-subunit isoforms, corresponds to the binding site for the β1-(and likely β3-) subunit immunoglobulin (Ig) domain. Nav1.8 contains a unique N-linked glycosylation site that likely prevents its interaction with the β2 and β4-subunit Ig domain. These isoform-specific glycans may have evolved to facilitate specific functional interactions, for example by redirecting β-subunit Ig-domains outwards to permit cis or trans supra-clustering within specialized cellular compartments such as the cardiomyocyte perinexal space. Further experimental work is necessary to validate these predictions.

Similarity between candidate drug targets and human proteins is commonly assessed to minimize the occurrence of side effects. Although numerous drugs have been found to disrupt the health of the human microbiome, no comprehensive comparison between established drug targets and the human microbiome metaproteome has yet been conducted. Therefore, herein, sequence and structure alignments between human and pathogen drug targets and representative human gut, oral, and vaginal microbiome metaproteomes were performed. Both human and pathogen drug targets were found to be similar in sequence, function, structure, and drug binding capacity to proteins in diverse pathogenic and non-pathogenic bacteria from all three microbiomes. The gut metaproteome was identified as particularly susceptible overall to off-target effects. Certain symptoms, such as infections and immune disorders, may be more common among drugs that non-selectively target host microbiota. These findings suggest that similarities between human microbiome metaproteomes and drug target candidates should be routinely checked.