한빛사 논문
Abstract
Hee-Jung Choia, Sabine Pokuttaa, Gregory W. Cadwellb, Andrey A. Bobkovb, Laurie A. Bankstonb, Robert C. Liddingtonb, and William I. Weisa,1
aDepartments of Structural Biology and Molecular and Cellular Physiology, Stanford University School of Medicine, 299 Campus Drive, Stanford, CA 94305; and
bProgram on Infectious Diseases, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037
Abstract
αE-catenin, an essential component of the adherens junction, interacts with the classical cadherin?β-catenin complex and with F-actin, but its precise role is unknown. αE-catenin also binds to the F-actin-binding protein vinculin, which also appears to be important in junction assembly. Vinculin and αE-catenin are homologs that contain a series of helical bundle domains, D1?D5. We mapped the vinculin-binding site to a sequence in D3a comprising the central two helices of a four-helix bundle. The crystal structure of this peptide motif bound to vinculin D1 shows that the two helices adopt a parallel, colinear arrangement suggesting that the αE-catenin D3a bundle must unfold in order to bind vinculin. We show that αE-catenin D3 binds strongly to vinculin, whereas larger fragments and full-length αE-catenin bind approximately 1,000-fold more weakly. Thus, intramolecular interactions within αE-catenin inhibit binding to vinculin. The actin-binding activity of vinculin is inhibited by an intramolecular interaction between the head (D1?D4) and the actin-binding D5 tail. In the absence of F-actin, there is no detectable binding of αE-catenin D3 to full-length vinculin; however, αE-catenin D3 promotes binding of vinculin to F-actin whereas full-length αE-catenin does not. These findings support the combinatorial or “coincidence” model of activation in which binding of high-affinity proteins to the vinculin head and tail is required to shift the conformational equilibrium of vinculin from a closed, autoinhibited state to an open, stable F-actin-binding state. The data also imply that αE-catenin must be activated in order to bind to vinculin.
Footnotes
1To whom correspondence should be addressed.
Author contributions: H.-J.C., S.P., L.A.B., R.C.L., and W.I.W. designed research; H.-J.C., S.P., G.W.C., and A.A.B. performed research; H.-J.C., S.P., L.A.B., R.C.L., and W.I.W. analyzed data; and R.C.L. and W.I.W. wrote the paper.
논문정보
관련 링크
연구자 키워드
관련분야 연구자보기
소속기관 논문보기
관련분야 논문보기
해당논문 저자보기