An alpha-actinin binding site of zyxin is essential for subcellular zyxin localization and alpha-actinin recruitment.
The LIM domain protein zyxin is a component of adherens type junctions, stress fibers, and highly dynamic membrane areas and appears to be involved in microfilament organization. Chicken zyxin and its human counterpart display less than 60% sequence identity, raising concern about their functional identity. Here, we demonstrate that human zyxin, like the avian protein, specifically interacts with alpha-actinin. Furthermore, we map the interaction site to a motif of approximately 22 amino acids, present in the N-terminal domain of human zyxin. This motif is both necessary and sufficient for alpha-actinin binding, whereas a downstream region, which is related in sequence, appears to be dispensable. A synthetic peptide comprising human zyxin residues 21-42 specifically binds to alpha-actinin in solid phase binding assays. In contrast to full-length zyxin, constructs lacking this motif do not interact with alpha-actinin in blot overlays and fail to recruit alpha-actinin in living cells. When zyxin lacking the alpha-actinin binding site is expressed as a fusion protein with green fluorescent protein, association of the recombinant protein with stress fibers is abolished, and targeting to focal adhesions is grossly impaired. Our results suggest a crucial role for the alpha-actinin-zyxin interaction in subcellular zyxin localization and microfilament organization.
Reinhard
M
M
Institute of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Versbacher Strasse 5, D-97078 Würzburg, Germany. Matthias.Reinhard@mail.uniwuerzburg.de
Zumbrunn
J
J
Jaquemar
D
D
Kuhn
M
M
Walter
U
U
Trueb
B
B
D000185:Actinin / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins; D001483:Base Sequence; D001665:Binding Sites; D005075:Biological Evolution; D002645:Chickens; D017124:Conserved Sequence; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D006023:Glycoproteins; D006801:Humans; D008667:Metalloproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism*; D060589:Zyxin
D030161:Avian Proteins; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D006023:Glycoproteins; D008667:Metalloproteins; D011993:Recombinant Fusion Proteins; C092842:ZYX protein, human; D060589:Zyxin; D000185:Actinin