Structural basis of actin sequestration by thymosin-β4: implications for WH2 proteins

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 doma...

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Bibliographic Details
Published in:The EMBO journal 2004-09, Vol.23 (18), p.3599-3608
Main Authors: Irobi, Edward, Aguda, Adeleke H, Larsson, Mårten, Guerin, Christophe, Yin, Helen L, Burtnick, Leslie D, Blanchoin, Laurent, Robinson, Robert C
Format: Article
Language:English
Subjects:
EMBO05
EMBO40
protein crystallography
SCAR
VCA
WASp
WH2
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Summary: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.
ISSN:0261-4189
1460-2075
1460-2075
DOI:10.1038/sj.emboj.7600372