The structural basis of actin interaction with multiple WH2/beta-thymosin motif-containing proteins.
Participation of actin in cellular processes relies on the dynamics of filament assembly. Filament elongation is fed by monomeric actin in complex with either profilin or a Wiscott-Aldrich syndrome protein (WASP) homology domain 2 (WH2)/beta-thymosin (betaT) domain. WH2/betaT motif repetition (typified by ciboulot) or combination with nonrelated domains (as found in N-WASP) results in proteins that yield their actin to filament elongation. Here, we report the crystal structures of actin bound hybrid proteins, constructed between gelsolin and WH2/betaT domains from ciboulot or N-WASP. We observe the C-terminal half of ciboulot domain 2 bound to actin. In solution, we show that cibolout domains 2 and 3 bind to both G- and F-actin, and that whole ciboulot forms a complex with two actin monomers. In contrast, the analogous portion of N-WASP WH2 domain 2 is detached from actin, indicating that the C-terminal halves of the betaT and WH2 motifs are not functionally analogous.
Department of Medical Biochemistry and Microbiology, Uppsala Biomedical Center, Uppsala University, Uppsala 751 23, Sweden.
Adeleke H
AH
Aguda
Bo
B
Xue
Edward
E
Irobi
Thomas
T
Préat
Robert C
RC
Robinson
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D004330:Drosophila; D029721:Drosophila Proteins / Q000737:chemistry* / Q000378:metabolism; D018260:Gelsolin / Q000737:chemistry*; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013947:Thymosin / Q000737:chemistry* / Q000378:metabolism; D051316:Wiskott-Aldrich Syndrome Protein / Q000737:chemistry* / Q000378:metabolism
D000199:Actins; D029721:Drosophila Proteins; D018260:Gelsolin; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D051316:Wiskott-Aldrich Syndrome Protein; C414741:cib protein, Drosophila; D013947:Thymosin