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FtsZ, a bacterial tubulin, plays a crucial role in the cytokinesis process. It shares structural similarities with tubulin, as it consists of two domains – N-terminal and C-terminal domains. The protein assembles to form single-stranded protofilaments that exhibit a dynamic phenomenon known as treadmilling where the FtsZ filaments appear to execute a unidirectional movement even though individual monomers constituting the filament do not move. Despite forming protofilaments, an FtsZ molecule requires a conformational switch to form stable contacts with neighboring subunits in a filament.

Autosomal dominant retinitis pigmentosa (ADRP) is a visual disorder which can result from many different mutations of the rhodopsin gene. In most cases the mutation results in a misfolded rhodopsin protein or a protein that does not bind with the retinal chromophore. Some mutations, however, yield rhodopsins which fold properly and bind the retinal chromophore, yet still result in ADRP. Here we investigate the activation mechanism of one such mutation which produces the G51V rhodopsin variant. Human WT and G51V were recombinantly produced and embedded in identical nanodiscs.

Symmetric homo-oligomeric proteins comprising multiple copies of identical subunits are abundant in all domains of life. To fulfill their biological function, these complexes undergo conformational changes, binding events, or post-translational modifications leading to loss of symmetry. Processivity clamp proteins that encircle DNA and play multiple roles in DNA replication and repair are archetypical homo-oligomeric symmetric protein complexes. The symmetrical nature of processivity clamps enables simultaneous interactions with multiple protein binding partners; such interactions result in asymmetric changes that facilitate the transition between clamp loading and DNA replication, and between DNA replication and repair.

When a blood clot occludes cerebral arteries, causing a stroke, a common cause of global death, thrombolytic therapy steps in as a highly effective treatment to restore the blood flow by dissolving the clot. Thrombolytic therapy is the use of plasminogen activators, including tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA), either separately or in combination. In this study, a mathematical model of thrombolysis has been developed for non-uniform fibrin clots, which have varying density levels nearer and farther from the cell surface.

Significance Statement: This review explains how combining two optical techniques—Förster Resonance Energy Transfer (FRET) and Fluorescence Correlation Spectroscopy (FCS)—can help us better understand how biological molecules move and interact over time and space. This approach offers a broader dynamic range and versatility than traditional methods used to study molecular structure and behavior. The review covers the basics of how FRET-FCS works and explores new ways it’s being used in research. It aims to give scientists from various fields a clear overview of the method’s strengths and potential, especially for investigating complex biological systems.

The assembly of integrin adhesion complexes at the inner leaflet of the plasma membrane regulates cell adhesion to the extracellular matrix. The multivalent protein interactions within the complexes and with the cell membrane display characteristics of membrane-associated biomolecular condensates driven by liquid-liquid phase separation. The composition of lipids and the distribution of the cell membrane are crucial for forming integrin adhesion complexes. Here, we report that PIP2 and PIP3in the model membrane synergistically regulate the formation of membrane-induced integrin adhesion condensates, which consist of β1 tails, kindlin, talin, paxillin, and FAK.

Statement of Significance: While single-cell metastasis is well-studied, mechanisms of collective cluster migration are less understood. Significant challenges include the lack of a fundamental physics perspective on collective cluster migration mechanisms and suitable physiologically relevant three-dimensional (3D) in vitro models that can recapitulate collective cluster migration. In this article, we developed a computational model depicting microtumor migration behaviors. Collective cell migration, with varying correlation lengths, exhibits different migratory modes such as directional and radial migration. These modes are predicted by in silico models and confirmed using experimental microtumor models. Machine learning methods were exploited to identify migratory modes. Our computational and experimental models are flexible in various circumstances, offering insights into cancer migration mechanisms.

SIGNIFICANT STATEMENT: Known as “the guardian of the genome”, the tumor suppressor protein p53 becomes activated by injuries to the DNA genome, and determines whether the cell must undergo self-destruction to avoid cancerous proliferation. P53 is in fact inactivated by mutations in over 50% of all cancers, and restoring its function is recognized as a therapeutic cancer target. A recent biochemical revolution in cell physiology and pathology are liquid entities known as biomolecular condensates. We show that p53 form condensates en route to pathological forms in a surprisingly similar manner to neurological amyloid diseases such as Alzheimer´s and Parkinson´s. We uncover the sequence of steps in the reaction, exposing flanks for a novel drug development platform based on the condensate paradigm.

1 Significance: This research presents the first method capable of concurrently analyzing a single molecule’s reaction kinetics and diffusion dynamics based solely on single photon arrival data. Utilizing single-molecule, single-photon confocal FRET data, we trace the continuous spatial trajectory and discrete state trajectories—encompassing conformational and photophysical changes—of individual molecules. This approach allows us to observe the reaction-diffusion dynamics of single molecules in real time without immobilizing them on surfaces, trapping them, or averaging signals across populations, thereby preserving single-molecule resolution.

Tubular membrane structures are ubiquitous in cells and in the membranes of intracellular organelles such as the Golgi complex and the endoplasmic reticulum. Tubulation plays essential roles in numerous biological processes, including filopodia growth, trafficking, ion transport, and cellular motility. Understanding the fundamental mechanism of the formation of membrane tubes is thus an important problem in the fields of biology and biophysics. Though extensive studies have shown that tubes can be formed due to localized forces acting on the membrane or by the spontaneous curvature induced by membrane-bound proteins, little is known about how membrane tubes are induced by glycocalyx, a sugar-rich layer at the cell surface.

Surfactant protein D (SP-D) plays an important role in the innate immune system by recognizing and binding to glycans on the surface of pathogens, facilitating their clearance. Despite its importance, the detailed binding mechanisms between SP-D and various pathogenic surface glycans remain elusive due to the limited experimentally solved protein-glycan crystal structures. To address this, we developed and validated a computational workflow that integrates Induced Fit Docking, MMGBSA binding free energy calculations, and Binding Pose MetaDynamics simulations to accurately predict stable SP-D-glycan complex structure and binding mechanisms.

Statement of Significance: In chromaffin cells, SNAP25-based FRET constructs (SCORE) revealed transient FRET increases within <0.5μm2 areas, preceding individual fusion events that reversed within seconds. It remained unknown whether this reversal stems from high-FRET complex disassembly or diffusion-mediated exchange with low-FRET complexes. Here, we performed whole-cell patch-clamp pulse stimulation with TIRF microscopy, imaging large ∼30μm2 areas of the cell footprint. Calcium currents induced FRET transients with the same decay time constant of ∼1.5s, significantly shorter than the time scale of diffusion. The SCORE FRET ratio thus reports in real time the dynamics of SNARE complex assembly and disassembly in live cells. Using Synaptobrevin 2/Cellubrevin double knock-out mouse chromaffin cells we show that vSNAREs are required for SNAP25 incorporation into SNARE complexes during priming.