Structural Basis for Specific Interaction of TGF beta Signaling Regulators SARA/Endofin with HD-PTP.Gahloth, D., Levy, C., Walker, L., Wunderley, L., Mould, A.P., Taylor, S., Woodman, P., Tabernero, L.
(2017) Structure 25: 1011-1024.e4
- PubMed: 28602823
- DOI: https://doi.org/10.1016/j.str.2017.05.005
- Primary Citation of Related Structures:
5MJY, 5MJZ, 5MK0, 5MK1, 5MK2, 5MK3
- PubMed Abstract:
SARA and endofin are endosomal adaptor proteins that drive Smad phosphorylation by ligand-activated transforming growth factor β/bone morphogenetic protein (TGFβ/BMP) receptors. We show in this study that SARA and endofin also recruit the tumor supressor HD-PTP, a master regulator of endosomal sorting and ESCRT-dependent receptor downregulation. High-affinity interactions occur between the SARA/endofin N termini, and the conserved hydrophobic region in the HD-PTP Bro1 domain that binds CHMP4/ESCRT-III. CHMP4 engagement is a universal feature of Bro1 proteins, but SARA/endofin binding is specific to HD-PTP. Crystallographic structures of HD-PTP Bro1 in complex with SARA, endofin, and three CHMP4 isoforms revealed that all ligands bind similarly to the conserved site but, critically, only SARA/endofin interact at a neighboring pocket unique to HD-PTP. The structures, together with mutagenesis and binding analysis, explain the high affinity and specific binding of SARA/endofin, and why they compete so effectively with CHMP4. Our data invoke models for how endocytic regulation of TGFβ/BMP signaling is controlled.
School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PT, UK.