In neurodegenerative diseases such as Alzheimer's disease, progressive neuronal damage is associated with the accumulation of abnormal tau filaments in the brain.

Polymerisation and disassembly govern the cellular functions of cytoskeletal proteins. In canonical nucleotide-dependent polymers such as actin and tubulin, nucleotide exchange occurs in soluble subunits but not within intact protofilaments. By contrast, the assembly dynamics and nucleotide dependency of the prokaryotic actin homolog MreB, whose polymerization into membrane associated filaments is essential for bacterial cell morphogenesis, remain poorly understood. We used total internal reflection fluorescence microscopy and high-speed atomic force microscopy to monitor the assembly of MreB on supported lipid bilayers in real time. ATP binding triggers MreB polymerization into symmetrically elongating pairs of filaments on cardiolipin-containing membranes. While ATP hydrolysis occurs within filaments and contributes to endwise disassembly, continuous nucleotide exchange within filaments tunes their stability on the membrane. Nucleotide cycling within MreB filaments defines a new class of biological polymer behavior and highlights the evolutionary divergence of mechanisms governing actin homologs assembly dynamics. ### Competing Interest Statement The authors have declared no competing interest. European Research Council, ERC 829 CoG No 772178 (R.C.L.)

In this meet-the-author Q&A, Structure's editor-in-chief, Karin Kühnel, speaks to Kevin Corbett from the University of California, San Diego, about his research group's recent Structure paper entitled "A bacteriophage tubulin forms microtubule-like assemblies with nine protofilaments" and his wo …

The Unstable Lattice: A New Model for Microtubule Tip Dynamics A new study in Biophysical Journal provides a detailed mechanistic model for the formation of protofilament clusters at the growing tips of microtubules. These dynamic cytoskeletal filaments, composed of α- and β-tubulin dimers, are essential for cell structure, intracellular transport, and chromosome segregation. The research posits that a fundamental lattice instability drives the clustering of protofilaments, offering a fresh perspective on the microscopic underpinnings of microtubule dynamic instability, a process critical to its cellular functions.

Combining cryoelectron tomography and single-particle cryoelectron microscopy, Basu et al. define a nine-protofilament assembly in the PhuZ protein of the E. coli-infecting bacteriophage Goslar. Gosla...

**Abstract:** This paper presents a novel technique, Dynamically Weighted Bayesian Filtering (DWBF), for investigating quantum tunneling within microtubule protofilaments with unprecedented resolution. Leveraging recent advances in cryogenic scanning tunneling microscopy (c-STM) and integrated quantum computing for Bayesian inference, DWBF offers a ten-fold improvement in spectral resolution compared to existing methods, enabling the direct observation and quantification of electron tunneling events within the protein lattice.

Microtubules are dynamic cytoskeletal polymers that add and lose tubulin dimers at their ends. Microtubule growth, shortening, and transitions betw...

First 3D-structure and first observation of organized protofilaments of MreB from a Gram-positive bacterium, suggesting a model where ATP drives the formation of dynamic pairs of MreB protofilaments o...

The ″neck″ region of kinesin is a structurally conserved element critical for force generation, stepping directionality, and cargo transport along microtubules, yet its atomic-scale structure in a fun...