Activation of a vinculin-binding site in the talin rod involves rearrangement of a five-helix bundle.
The interaction between the cytoskeletal proteins talin and vinculin plays a key role in integrin-mediated cell adhesion and migration. We have determined the crystal structures of two domains from the talin rod spanning residues 482-789. Talin 482-655, which contains a vinculin-binding site (VBS), folds into a five-helix bundle whereas talin 656-789 is a four-helix bundle. We show that the VBS is composed of a hydrophobic surface spanning five turns of helix 4. All the key side chains from the VBS are buried and contribute to the hydrophobic core of the talin 482-655 fold. We demonstrate that the talin 482-655 five-helix bundle represents an inactive conformation, and mutations that disrupt the hydrophobic core or deletion of helix 5 are required to induce an active conformation in which the VBS is exposed. We also report the crystal structure of the N-terminal vinculin head domain in complex with an activated form of talin. Activation of the VBS in talin and the recruitment of vinculin may support the maturation of small integrin/talin complexes into more stable adhesions.
Department of Biochemistry, University of Leicester, Leicester, UK.
Evangelos
E
Papagrigoriou
Alexandre R
AR
Gingras
Igor L
IL
Barsukov
Neil
N
Bate
Ian J
IJ
Fillingham
Bipin
B
Patel
Ronald
R
Frank
Wolfgang H
WH
Ziegler
Gordon C K
GC
Roberts
David R
DR
Critchley
Jonas
J
Emsley
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D040081:Protein Array Analysis; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D016608:Talin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016596:Vinculin / Q000737:chemistry / Q000378:metabolism*
D008024:Ligands; D016608:Talin; D016596:Vinculin