Wiskott-Aldrich syndrome protein induces actin clustering without direct binding to Cdc42.
WASP (Wiskott-Aldrich syndrome protein) was identified as the gene product whose mutation causes the human hereditary disease Wiskott-Aldrich syndrome. WASP contains many functional domains and has been shown to induce the formation of clusters of actin filaments in a manner dependent on Cdc42. However, there has been no report investigating what domain(s) is(are) important for the function. Here we present for the first time the results of detailed analyses on the domain-function relationship of WASP. First, the C-terminal verprolin-cofilin-acidic domain was shown to be essential for the regulation of actin cytoskeleton. In addition, we found that the clustering of WASP itself is distinct from actin clustering. The partial protein containing the region from the N-terminal pleckstrin homology domain to the basic residue-rich region also clustered especially around the nucleus as wild type WASP without inducing actin clustering. Finally, we obtained the quite unexpected result that a WASP mutant deficient in binding to Cdc42 still induced actin cluster formation, indicating that direct interaction between Cdc42 and WASP is not required for the regulation of actin cytoskeleton. This result may explain why no Wiskott-Aldrich syndrome patients have been identified with a missense mutation in the Cdc42-binding site.
Kato
M
M
Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Chiba 263-8522, Japan.
Miki
H
H
Imai
K
K
Nonoyama
S
S
Suzuki
T
T
Sasakawa
C
C
Takenawa
T
T
D051339:Actin Depolymerizing Factors; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D011506:Proteins / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014923:Wiskott-Aldrich Syndrome / Q000378:metabolism*; D051316:Wiskott-Aldrich Syndrome Protein; D020764:cdc42 GTP-Binding Protein
D051339:Actin Depolymerizing Factors; D000199:Actins; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D008840:Microfilament Proteins; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; C090350:VRP1 protein, S cerevisiae; C495767:WAS protein, human; D051316:Wiskott-Aldrich Syndrome Protein; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein