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Structural basis of actin sequestration by thymosin‐β4: implications for WH2 proteins
Author(s) -
Irobi Edward,
Aguda Adeleke H,
Larsson Mårten,
Guerin Christophe,
Yin Helen L,
Burtnick Leslie D,
Blanchoin Laurent,
Robinson Robert C
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600372
Subject(s) - biology , actin , microbiology and biotechnology , thymosin , computational biology , pulmonary sequestration , biochemistry , linguistics , philosophy , lung
The WH2 (Wiscott–Aldridge syndrome protein homology domain 2) repeat is an actin interacting motif found in monomer sequestering and filament assembly proteins. We have stabilized the prototypical WH2 family member, thymosin‐β4 (Tβ4), with respect to actin, by creating a hybrid between gelsolin domain 1 and the C‐terminal half of Tβ4 (G1‐Tβ4). This hybrid protein sequesters actin monomers, severs actin filaments and acts as a leaky barbed end cap. Here, we present the structure of the G1‐Tβ4:actin complex at 2 Å resolution. The structure reveals that Tβ4 sequesters by capping both ends of the actin monomer, and that exchange of actin between Tβ4 and profilin is mediated by a minor overlap in binding sites. The structure implies that multiple WH2 motif‐containing proteins will associate longitudinally with actin filaments. Finally, we discuss the role of the WH2 motif in arp2/3 activation.