Structural Principles in Robo Activation and Auto-inhibition

Reut Barak, Galit Yom-Tov, Julia Guez-Haddad, Lital Gasri-Plotnitsky, Roy Maimon, Moran Cohen-Berkman, Andrew A. McCarthy, Eran Perlson, Sivan Henis-Korenblit, Michail N. Isupov, Yarden Opatowsky*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Proper brain function requires high-precision neuronal expansion and wiring, processes controlled by the transmembrane Roundabout (Robo) receptor family and their Slit ligands. Despite their great importance, the molecular mechanism by which Robos’ switch from “off” to “on” states remains unclear. Here, we report a 3.6 Å crystal structure of the intact human Robo2 ectodomain (domains D1–8). We demonstrate that Robo cis dimerization via D4 is conserved through hRobo1, 2, and 3 and the C. elegans homolog SAX-3 and is essential for SAX-3 function in vivo. The structure reveals two levels of auto-inhibition that prevent premature activation: (1) cis blocking of the D4 dimerization interface and (2) trans interactions between opposing Robo receptors that fasten the D4-blocked conformation. Complementary experiments in mouse primary neurons and C. elegans support the auto-inhibition model. These results suggest that Slit stimulation primarily drives the release of Robo auto-inhibition required for dimerization and activation. Intra- and inter-molecular contacts of Robo receptor auto-inhibit its dimerization, critical for axon guidance and signaling.

Original languageEnglish
Pages (from-to)272-285.e16
JournalCell
Volume177
Issue number2
DOIs
StatePublished - 4 Apr 2019

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