Mechanism of filament nucleation and branch stability revealed by the structure of the Arp2/3 complex at actin branch junctions.

Actin branch junctions are conserved cytoskeletal elements critical for the generation of protrusive force during actin polymerization-driven cellular motility. Assembly of actin branch junctions requires the Arp2/3 complex, upon activation, to initiate a new actin (daughter) filament branch from th...

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Format: Article
Language:English
Published: Public Library of Science (PLoS) 2005-11-01
Series:PLoS Biology
Online Access:http://dx.doi.org/10.1371/journal.pbio.0030383
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spelling doaj-b05565bb1eec4e7eb2cee08b0ff7b6782021-07-02T08:26:07ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852005-11-01311e383Mechanism of filament nucleation and branch stability revealed by the structure of the Arp2/3 complex at actin branch junctions.Actin branch junctions are conserved cytoskeletal elements critical for the generation of protrusive force during actin polymerization-driven cellular motility. Assembly of actin branch junctions requires the Arp2/3 complex, upon activation, to initiate a new actin (daughter) filament branch from the side of an existing (mother) filament, leading to the formation of a dendritic actin network with the fast growing (barbed) ends facing the direction of movement. Using genetic labeling and electron microscopy, we have determined the structural organization of actin branch junctions assembled in vitro with 1-nm precision. We show here that the activators of the Arp2/3 complex, except cortactin, dissociate after branch formation. The Arp2/3 complex associates with the mother filament through a comprehensive network of interactions, with the long axis of the complex aligned nearly perpendicular to the mother filament. The actin-related proteins, Arp2 and Arp3, are positioned with their barbed ends facing the direction of daughter filament growth. This subunit map brings direct structural insights into the mechanism of assembly and mechanical stability of actin branch junctions.http://dx.doi.org/10.1371/journal.pbio.0030383
collection DOAJ
language English
format Article
sources DOAJ
title Mechanism of filament nucleation and branch stability revealed by the structure of the Arp2/3 complex at actin branch junctions.
spellingShingle Mechanism of filament nucleation and branch stability revealed by the structure of the Arp2/3 complex at actin branch junctions.
PLoS Biology
title_short Mechanism of filament nucleation and branch stability revealed by the structure of the Arp2/3 complex at actin branch junctions.
title_full Mechanism of filament nucleation and branch stability revealed by the structure of the Arp2/3 complex at actin branch junctions.
title_fullStr Mechanism of filament nucleation and branch stability revealed by the structure of the Arp2/3 complex at actin branch junctions.
title_full_unstemmed Mechanism of filament nucleation and branch stability revealed by the structure of the Arp2/3 complex at actin branch junctions.
title_sort mechanism of filament nucleation and branch stability revealed by the structure of the arp2/3 complex at actin branch junctions.
publisher Public Library of Science (PLoS)
series PLoS Biology
issn 1544-9173
1545-7885
publishDate 2005-11-01
description Actin branch junctions are conserved cytoskeletal elements critical for the generation of protrusive force during actin polymerization-driven cellular motility. Assembly of actin branch junctions requires the Arp2/3 complex, upon activation, to initiate a new actin (daughter) filament branch from the side of an existing (mother) filament, leading to the formation of a dendritic actin network with the fast growing (barbed) ends facing the direction of movement. Using genetic labeling and electron microscopy, we have determined the structural organization of actin branch junctions assembled in vitro with 1-nm precision. We show here that the activators of the Arp2/3 complex, except cortactin, dissociate after branch formation. The Arp2/3 complex associates with the mother filament through a comprehensive network of interactions, with the long axis of the complex aligned nearly perpendicular to the mother filament. The actin-related proteins, Arp2 and Arp3, are positioned with their barbed ends facing the direction of daughter filament growth. This subunit map brings direct structural insights into the mechanism of assembly and mechanical stability of actin branch junctions.
url http://dx.doi.org/10.1371/journal.pbio.0030383
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