TY - JOUR
T1 - Rap1 binding and a lipid-dependent helix in talin F1 domain promote integrin activation in tandem
AU - Gingras, Alexandre R.
AU - Lagarrigue, Frederic
AU - Cuevas, Monica N.
AU - Valadez, Andrew J.
AU - Zorovich, Marcus
AU - McLaughlin, Wilma
AU - Lopez-Ramirez, Miguel Alejandro
AU - Seban, Nicolas
AU - Ley, Klaus
AU - Kiosses, William B.
AU - Ginsberg, Mark H.
N1 - Funding Information:
This work was supported by the National Institutes of Health, National Heart, Lung, and Blood Institute (grant HL 139947 to M.H. Ginsberg, grant K01HL 133530-01 to M.A. Lopez-Ramirez, and grant HL 078784 to M.H. Ginsberg and K. Ley), and American Heart Association Career Development Award 18CDA34110228 (to F. Lagarrigue) and Grant-In-Aid 16GRNT29650005 (to A.R. Gingras). The Zeiss LSM880 was supported by National Institutes of Health grant S10OD021831. The authors declare no competing financial interests.
Publisher Copyright:
© 2019 Gingras et al.
PY - 2019/6/3
Y1 - 2019/6/3
N2 - Rap1 GTPases bind effectors, such as RIAM, to enable talin1 to induce integrin activation. In addition, Rap1 binds directly to the talin1 F0 domain (F0); however, this interaction makes a limited contribution to integrin activation in CHO cells or platelets. Here, we show that talin1 F1 domain (F1) contains a previously undetected Rap1-binding site of similar affinity to that in F0. A structure-guided point mutant (R118E) in F1, which blocks Rap1 binding, abolishes the capacity of Rap1 to potentiate talin1-induced integrin activation. The capacity of F1 to mediate Rap1-dependent integrin activation depends on a unique loop in F1 that has a propensity to form a helix upon binding to membrane lipids. Basic membrane-facing residues of this helix are critical, as charge-reversal mutations led to dramatic suppression of talin1-dependent activation. Thus, a novel Rap1-binding site and a transient lipid-dependent helix in F1 work in tandem to enable a direct Rap1–talin1 interaction to cause integrin activation.
AB - Rap1 GTPases bind effectors, such as RIAM, to enable talin1 to induce integrin activation. In addition, Rap1 binds directly to the talin1 F0 domain (F0); however, this interaction makes a limited contribution to integrin activation in CHO cells or platelets. Here, we show that talin1 F1 domain (F1) contains a previously undetected Rap1-binding site of similar affinity to that in F0. A structure-guided point mutant (R118E) in F1, which blocks Rap1 binding, abolishes the capacity of Rap1 to potentiate talin1-induced integrin activation. The capacity of F1 to mediate Rap1-dependent integrin activation depends on a unique loop in F1 that has a propensity to form a helix upon binding to membrane lipids. Basic membrane-facing residues of this helix are critical, as charge-reversal mutations led to dramatic suppression of talin1-dependent activation. Thus, a novel Rap1-binding site and a transient lipid-dependent helix in F1 work in tandem to enable a direct Rap1–talin1 interaction to cause integrin activation.
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U2 - 10.1083/JCB.201810061
DO - 10.1083/JCB.201810061
M3 - Article
C2 - 30988001
AN - SCOPUS:85067215973
SN - 0021-9525
VL - 218
SP - 1799
EP - 1809
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 6
ER -