8OH4

Subtomogram averaging structure of cofilactin filament inside microtubule lumen of Drosophila S2 cell protrusion.

Summary for 8OH4

• Entry DOI: 10.2210/pdb8oh4/pdb
• EMDB information: 16877
• Descriptor: Actin-5C, Cofilin/actin-depolymerizing factor homolog (2 entities in total)
• Functional Keywords: cytoskeleton, filament, actin, cofilactin, contractile protein
• Biological source: Drosophila (fruit flies); More
• Total number of polymer chains: 14
• Total formula weight: 432371.01

Authors

Ventura Santos, C.,Carter, A.P. (deposition date: 2023-03-20, release date: 2023-05-10, Last modification date: 2024-07-24)

Primary citation

Santos, C.V.,Rogers, S.L.,Carter, A.P.
CryoET shows cofilactin filaments inside the microtubule lumen.
Biorxiv, 2023

PubMed Abstract: Cytoplasmic microtubules are tubular polymers that can harbor small proteins or filaments inside their lumen. The identity of these objects and what causes their accumulation has not been conclusively established. Here, we used cryogenic electron tomography (cryoET) of S2 cell protrusions and found filaments inside the microtubule lumen, which resemble those reported recently in human HAP1 cells. The frequency of these filaments increased upon inhibition of the sarco/endoplasmic reticulum Ca ATPase (SERCA) with the small-molecule drug thapsigargin. Subtomogram averaging showed that the luminal filaments adopt a helical structure reminiscent of cofilin-bound actin (cofilactin). Consistent with this, cofilin was activated in cells under the same conditions that increased luminal filament occurrence. Furthermore, RNAi knock-down of cofilin reduced the frequency of luminal filaments with cofilactin morphology. These results suggest that cofilin activation stimulates its accumulation on actin filaments inside the microtubule lumen.

PubMed: 37034688
DOI: 10.1101/2023.03.31.535077

Experimental method

ELECTRON MICROSCOPY (16.5 Å)