Mechanism of IRSp53 inhibition and combinatorial activation by Cdc42 and downstream effectors.
David J KastChangsong YangAndrea DisanzaMalgorzata BoczkowskaYadaiah MadasuGiorgio ScitaTatyana SvitkinaRoberto DominguezPublished in: Nature structural & molecular biology (2014)
The Rho family GTPase effector IRSp53 has essential roles in filopodia formation and neuronal development, but its regulatory mechanism is poorly understood. IRSp53 contains a membrane-binding BAR domain followed by an unconventional CRIB motif that overlaps with a proline-rich region (CRIB-PR) and an SH3 domain that recruits actin cytoskeleton effectors. Using a fluorescence reporter assay, we show that human IRSp53 adopts a closed inactive conformation that opens synergistically with the binding of human Cdc42 to the CRIB-PR and effector proteins, such as the tumor-promoting factor Eps8, to the SH3 domain. The crystal structure of Cdc42 bound to the CRIB-PR reveals a new mode of effector binding to Rho family GTPases. Structure-inspired mutations disrupt autoinhibition and Cdc42 binding in vitro and decouple Cdc42- and IRSp53-dependent filopodia formation in cells. The data support a combinatorial mechanism of IRSp53 activation.
Keyphrases
- type iii
- cell cycle
- endothelial cells
- regulatory t cells
- dendritic cells
- induced apoptosis
- induced pluripotent stem cells
- dna binding
- pluripotent stem cells
- high throughput
- cell cycle arrest
- cell proliferation
- protein kinase
- binding protein
- smooth muscle
- immune response
- single molecule
- electronic health record
- endoplasmic reticulum stress
- energy transfer
- subarachnoid hemorrhage