3BYH

Model of actin-fimbrin ABD2 complex

Summary for 3BYH

• Entry DOI: 10.2210/pdb3byh/pdb
• Descriptor: Actin, fimbrin ABD2 (2 entities in total)
• Functional Keywords: helical filament, protein polymer, acetylation, atp-binding, cytoplasm, cytoskeleton, methylation, nucleotide-binding, phosphoprotein, structural protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 2
• Total formula weight: 68415.83

Authors

Galkin, V.E.,Orlova, A.,Cherepanova, O.,Lebart, M.C.,Egelman, E.H. (deposition date: 2008-01-16, release date: 2008-02-19, Last modification date: 2024-02-21)

Primary citation

Galkin, V.E.,Orlova, A.,Cherepanova, O.,Lebart, M.C.,Egelman, E.H.
High-resolution cryo-EM structure of the F-actin-fimbrin/plastin ABD2 complex.
Proc.Natl.Acad.Sci.Usa, 105:1494-1498, 2008

PubMed Abstract: Many actin binding proteins have a modular architecture, and calponin-homology (CH) domains are one such structurally conserved module found in numerous proteins that interact with F-actin. The manner in which CH-domains bind F-actin has been controversial. Using cryo-EM and a single-particle approach to helical reconstruction, we have generated 12-A-resolution maps of F-actin alone and F-actin decorated with a fragment of human fimbrin (L-plastin) containing tandem CH-domains. The high resolution allows an unambiguous fit of the crystal structure of fimbrin into the map. The interaction between fimbrin ABD2 (actin binding domain 2) and F-actin is different from any interaction previously observed or proposed for tandem CH-domain proteins, showing that the structural conservation of the CH-domains does not lead to a conserved mode of interaction with F-actin. Both the stapling of adjacent actin protomers and the additional closure of the nucleotide binding cleft in F-actin when the fimbrin fragment binds may explain how fimbrin can stabilize actin filaments. A mechanism is proposed where ABD1 of fimbrin becomes activated for binding a second actin filament after ABD2 is bound to a first filament, and this can explain how mutations of residues buried in the interface between ABD2 and ABD1 can rescue temperature-sensitive defects in actin.

PubMed: 18234857
DOI: 10.1073/pnas.0708667105

Experimental method

ELECTRON MICROSCOPY (12 Å)