9FJU

Structure of the DNase I- and phalloidin-bound pointed end of F-actin (conformer 1)

Summary for 9FJU

• Entry DOI: 10.2210/pdb9fju/pdb
• Related: 9FJM 9FJO
• EMDB information: 50506 50507 50516
• Related PRD ID: PRD_002366
• Descriptor: Actin, cytoplasmic 1, N-terminally processed, Deoxyribonuclease-1, Phalloidin, ... (7 entities in total)
• Functional Keywords: actin, phalloidin, filament, pointed end, dnase i, structural protein
• Biological source: Bos taurus (cattle); More
• Total number of polymer chains: 10
• Total formula weight: 235774.33

Authors

Boiero Sanders, M.,Oosterheert, W.,Hofnagel, O.,Bieling, P.,Raunser, S. (deposition date: 2024-05-31, release date: 2024-09-11, Last modification date: 2024-10-02)

Primary citation

Boiero Sanders, M.,Oosterheert, W.,Hofnagel, O.,Bieling, P.,Raunser, S.
Phalloidin and DNase I-bound F-actin pointed end structures reveal principles of filament stabilization and disassembly.
Nat Commun, 15:7969-7969, 2024

PubMed Abstract: Actin filament turnover involves subunits binding to and dissociating from the filament ends, with the pointed end being the primary site of filament disassembly. Several molecules modulate filament turnover, but the underlying mechanisms remain incompletely understood. Here, we present three cryo-EM structures of the F-actin pointed end in the presence and absence of phalloidin or DNase I. The two terminal subunits at the undecorated pointed end adopt a twisted conformation. Phalloidin can still bind and bridge these subunits, inducing a conformational shift to a flattened, F-actin-like state. This explains how phalloidin prevents depolymerization at the pointed end. Interestingly, two DNase I molecules simultaneously bind to the phalloidin-stabilized pointed end. In the absence of phalloidin, DNase I binding would disrupt the terminal actin subunit packing, resulting in filament disassembly. Our findings uncover molecular principles of pointed end regulation and provide structural insights into the kinetic asymmetry between the actin filament ends.

PubMed: 39261469
DOI: 10.1038/s41467-024-52251-3

Experimental method

ELECTRON MICROSCOPY (3.84 Å)