Structural basis of Notch recognition by human γ-secretase

Extracellular interface between APP and Nicastrin regulates Aβ length and response to γ‐secretase modulators

“…The GSEC‐APP C83 complex shows the APP‐K12 residue (corresponding to K28 in APP C99 ) in the proximity to the NCT‐241 residue; however, since the interface in the GSEC‐APP C83 structure is not fully resolved, it is possible that the cross‐linking of GSEC (PSEN1‐Q112C) to the APP C83 V8C substrate affected this region in the atomic model (Fig EV5B). The functional data presented here, together with the novel GSEC–substrate co‐structures (Yang et al , ; Zhou et al , ), suggest a conserved mechanism for the stabilization of GSEC–substrate interactions and may support the involvement of NCT ectodomain in the substrate recognition by the GSEC complex, by stabilizing the initial GSEC–substrate assembly. Of note, the ectodomain of NCT was initially proposed to act as a substrate receptor in the protease, with the anionic NCT‐E322 residue and the free N‐terminal amine group of the substrate interacting (Shah et al , ).…”

“…Collectively, the presented data demonstrate for the first time the existence of an extracellular NCT‐APP interface implicated in the modulation of the strength of GSEC‐APP/Aβ interactions (and thus Aβ length) as well as in the response of E‐S complexes to GSMs (E‐S stabilizers). Based on our original findings, the novel E‐S structural data (Yang et al , ; Zhou et al , ) and the literature, we propose that the extracellular GSEC (NCT‐PSEN)‐APP interface encompassing the aa region 241‐242 in NCT ectodomain, K28 in APP and the first extracellular loop of PSEN plays a critical role in the stabilization of GSEC‐APP/Aβ n interactions and is involved in the binding of selected imidazole‐based GSMs. Notably, the idea of selectively targeting APP processing with substrate targeting compounds (Kukar et al , ) has been raised in the past but has been abandoned due to studies, showing that potent pharmaceutics modulating Aβ length bind rather to the protease complex.…”

“…During the preparation of this report, the co‐structures of the GSEC with the Notch or APP C83 substrate became available (Yang et al , ; Zhou et al , ). Interestingly, the GSEC–Notch complex shows an extracellular interface between the ectodomains of the NCT subunit and Notch, with the NCT‐241–242 aa located at the E‐S interface (Fig EV5A).…”

Making sense out of missense mutations: Mechanistic dissection of Notch receptors through structure‐function studies in Drosophila

“…It is interesting to note that the NICD has also been shown to form a dimer when bound to paired CSL-binding sites on DNA to boost transcription of certain target genes (Arnett et al, 2010). Further structural biological studies of Notch and its ligands in their native states at atomic resolution using techniques such as cryo-EM (Yang et al, 2019) may allow scientists to observe how these proteins actually interact in vivo. Further structural biological studies of Notch and its ligands in their native states at atomic resolution using techniques such as cryo-EM (Yang et al, 2019) may allow scientists to observe how these proteins actually interact in vivo.…”

“…Hence, it is important to understand the structural basis by which different domains within both extracellular and intracellular regions of Notch contribute to higher-order complex formation to obtain a full understanding of how this receptor works at the molecular level. Further structural biological studies of Notch and its ligands in their native states at atomic resolution using techniques such as cryo-EM (Yang et al, 2019) may allow scientists to observe how these proteins actually interact in vivo.…”