YouTube video by Bui Lab

Motile cilia are unique organelles with the ability to move autonomously. The force generated by beating cilia propels cells and moves fluids. The cil…

Eukaryotic cilia and flagella are thin structures present on the surface of cells, playing vital roles in signaling and cellular motion. Cilia structures rely on intraflagellar transport (IFT), which ...

Ciliogenesis and cilia motility rely on the coordinated actions of diverse dyneins, yet the complexity of these motor proteins in cilia has posed challenges for understanding their specific roles. Tra...

Agrobacterium tumefaciens is a natural genetic engineer that transfers DNA into plants and this is the most frequently applied process for the generation of genetically modified plants. DNA transfer is mediated by a type IV secretion system localized in the cell envelope and extracellular T-pili. We here report the cryo-electron microscopic structures of the T-pilus at 3.2Å resolution and that of the related plasmid pKM101-determined N-pilus at 3Å resolution. Both pili contain a main pilus protein (VirB2 in A. tumefaciens and TraM in pKM101) and phospholipids arranged in a 5-start helical assembly. They contain positively charged amino acids in the pilus lumen and the lipids are positively charged in the T-pilus (phosphatidylcholine) conferring overall positive charge to the lumen. Mutagenesis of the lumen-exposed Arg91 residue in VirB2 resulted in protein destabilization and loss of pilus formation. Our results reveal that different phospholipids can be incorporated into type IV secretion system pili and that the charge of the lumen is of functional importance. ### Competing Interest Statement The authors have declared no competing interest.

Intraflagellar transport for ciliary assembly and maintenance is driven by dynein and kinesins specific for the cilia. It has been shown that anterograde and retrograde transports run on different regions of the doublet microtubule, i.e., separate train tracks. However, little is known about the regulatory mechanism of this selective process. Since the doublet microtubule is known to display specific post-translational modifications of tubulins, i.e. “tubulin code”, for molecular motor regulations, we investigated the motility of ciliary specific dynein-2 under different post-translational modification by coarse-grained molecular dynamics. Our setup allows us to simulate the stochastic stepping behaviors of dynein-2 on un-modified, detyrosinated, poly-glutamylated and poly-glycylated microtubules in silico. Our study revealed that poly-glutamylation can play an inhibitory effect on dynein-2 motility. Our result indicates that poly-glutamylation of the B-tubule of the doublet microtubule can be used as an efficient means to target retrograde intraflagellar transport onto the A-tubule. ### Competing Interest Statement The authors have declared no competing interest.

image image Cryo‐EM structure of the outer dynein arm (ODA) complex attached to the doublet microtubule combined with the coarse‐grained molecular dynamics (MD) simulation reveals the active conformation of the ODA and the activation ...