Miller, H. L. | bioRxiv Science

bioRxiv2026

Open filament tracks drive Bacteroidota gliding motility

Bacteria of the phylum Bacteroidota glide across surfaces using adhesins that attach to the substratum and are propelled along the cell body by an underlying track. The track is currently thought to form a single closed loop around the cell. Here we use 3D super-resolution tracking of single adhesin molecules in Flavobacterium johnsoniae to characterize adhesin movements in unprecedented detail. Our data overturn multiple aspects of the single closed loop model by showing that adhesins follow non-repeating trajectories that cross, make sharp turns, and exhibit reversals and circular paths. We develop a new model for Bacteroidota gliding in which the track network comprises multiple independently moving, open filaments. This supramolecular organization resembles that of other moving bacterial filaments such as MreB and FtsZ, suggesting that open filaments are a common organising principle in the bacterial cytoskeleton.

microbiology↗

bioRxiv2024

A Methodology for Specific Disruption of Microtubules in Dendritic Spines

Dendritic spines, the mushroom-shaped extensions along dendritic shafts of excitatory neurons, are critical for synaptic function and are one of the first neuronal structures disrupted in neurodevelopmental and neurodegenerative diseases. Microtubule (MT) polymerization into dendritic spines is an activity-dependent process capable of affecting spine shape and function. Studies have shown that MT polymerization into spines occurs specifically in spines undergoing plastic changes. However, discerning the function of MT invasion of dendritic spines requires the specific inhibition of MT polymerization into spines, while leaving MT dynamics in the dendritic shaft, synaptically connected axons and associated glial cells intact. This is not possible with the unrestricted, bath application of pharmacological compounds. To specifically disrupt MT entry into spines we coupled a MT elimination domain (MTED) from the Efa6 protein to the actin filament-binding peptide LifeAct. LifeAct was chosen because actin filaments are highly concentrated in spines and are necessary for MT invasions. Temporally controlled expression of this LifeAct-MTED construct inhibits MT entry into dendritic spines, while preserving typical MT dynamics in the dendrite shaft. Expression of this construct will allow for the determination of the function of MT invasion of spines and more broadly, to discern how MT-actin interactions affect cellular processes. Significance StatementO_LIThe LifeAct-MTED construct provides spatial and temporal control of microtubule depolymerization within individual cells C_LIO_LITargeting this construct directly to spines allows for the specific inhibition of microtubule dynamics into dendritic spines, without affecting microtubule dynamics in the dendritic shaft C_LIO_LIImplementation of the construct will allow for the testing of microtubule contributions to specific biological processes, without global disruption of microtubule dynamics C_LI

neuroscience↗