8e9b
From Proteopedia
Cryo-EM structure of S. pombe Arp2/3 complex in the branch junction
Structural highlights
FunctionARP3_SCHPO Functions as ATP-binding component of the Arp2/3 complex which is involved in regulation of actin polymerization and together with an activating nucleation-promoting factor (NPF) mediates the formation of branched actin networks. Seems to contact the pointed end of the daughter actin filament (By similarity). May be involved in cytokinesis. Publication Abstract from PubMedWe reconstructed the structure of actin filament branch junctions formed by fission yeast Arp2/3 complex at 3.5 A resolution from images collected by electron cryo-microscopy. During specimen preparation, all of the actin subunits and Arp3 hydrolyzed their bound adenosine triphosphate (ATP) and dissociated the gamma-phosphate, but Arp2 retained the gamma-phosphate. Binding tightly to the side of the mother filament and nucleating the daughter filament growing as a branch requires Arp2/3 complex to undergo a dramatic conformational change where two blocks of structure rotate relative to each other about 25 degrees to align Arp2 and Arp3 as the first two subunits in the branch. During branch formation, Arp2/3 complex acquires more than 8,000 A(2) of new buried surface, accounting for the stability of the branch. Inactive Arp2/3 complex binds only transiently to the side of an actin filament, because its conformation allows only a subset of the interactions found in the branch junction. Mechanism of actin filament branch formation by Arp2/3 complex revealed by a high-resolution cryo-EM structureof the branch junction.,Chou SZ, Chatterjee M, Pollard TD Proc Natl Acad Sci U S A. 2022 Dec 6;119(49):e2206722119. doi: , 10.1073/pnas.2206722119. Epub 2022 Nov 29. PMID:36442092[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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