Site-specific phosphorylation of PSD-95 dynamically regulates the post-synaptic density as observed by phase separation

Vistrup-Parry, Maria; Chen, Xudong; Johansen, Thea L.; Bach, Sofie; Buch-Larsen, Sara C.; Bartling, Christian R. O.; Ma, Chenxue; Clemmensen, Louise S.; Nielsen, Michael L.; Zhang, Mingjie; Strømgaard, Kristian

doi:10.1101/2021.03.03.433754

Cited by 3 publications

(4 citation statements)

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“…Indeed, α7 nAChR binds to the PDZ domain of PICK1 with an affinity of ∼3 μM, 15,16 which significantly surpasses the affinities observed for PDZ1 (∼100 μM) and PDZ1−2 (12 μM), and is comparable to the affinity of PDZ-95 (1.2 μM) for binding iGluRs. 59 PDZ-95, a key scaffolding protein, plays a crucial role in anchoring iGluRs and other receptors to the cell surface membranes. 60−65 Interestingly, despite similar binding affinities, PICK1 fails to stabilize α7 nAChR clusters in the same manner that PSD-95 does for iGluRs.…”

Section: ■ Resultsmentioning

confidence: 99%

Unconventional PDZ Recognition Revealed in α7 nAChR-PICK1 Complexes

Bondarenko,

Chen,

Tillman

et al. 2024

ACS Chem. Neurosci.

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PDZ domains are modular domains that conventionally bind to C terminal or internal motifs of target proteins to control cellular functions through the regulation of protein complex assemblies. Almost all reported structures of PDZ-target protein complexes rely on fragments or peptides as target proteins. No intact target protein complexed with PDZ was structurally characterized. In this study, we used NMR spectroscopy and other biochemistry and biophysics tools to uncover insights into structural coupling between the PDZ domain of protein interacting with C-kinase 1 (PICK1) and α7 nicotinic acetylcholine receptors (α7 nAChR). Notably, the intracellular domains of both α7 nAChR and PICK1 PDZ exhibit a high degree of plasticity in their coupling. Specifically, the MA helix of α7 nAChR interacts with residues lining the canonical binding site of the PICK1 PDZ, while flexible loops also engage in protein−protein interactions. Both hydrophobic and electrostatic interactions mediate the coupling. Overall, the resulting structure of the α7 nAChR-PICK1 complex reveals an unconventional PDZ binding mode, significantly expanding the repertoire of functionally important PDZ interactions.

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Section: ■ Resultsmentioning

confidence: 99%

Unconventional PDZ Recognition Revealed in α7 nAChR-PICK1 Complexes

Bondarenko,

Chen,

Tillman

et al. 2024

ACS Chem. Neurosci.

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“…The C-terminus of stargazin (TARP γ2 subunit) and PSD-95 exhibit phase separation at an average concentration of 10 μM (27). In addition, the dissociation constant 𝐾 𝑑 between C-terminus of stargazin and full-length PDZ-95 was measured to be 0.63 ± 0.6 ( 27), 1.2 (result from ITC assay), or 2.66 ± 0.07 μM (result from FP saturation assay) (39). We assumed the experimental 𝐾 𝑑 to be 1.0 μM.…”

Section: Resultsmentioning

confidence: 99%

“…The first assay aimed to reproduce the experimentally measured dissociation constant 𝐾 𝑑 between TARPc and PSD-95. The dissociation constant 𝐾 𝑑 of TARPc's and PSD-95 in experiments ranged between 0.63-2.09 μM(27,39) (we used 1.0 μM as the representative experimental 𝐾 𝑑 in this study). We conducted simulations of a single pair of molecules: one molecule each of PSD-95 and TARPc were included in a 50 × 50 × 50 nm cubic box.…”

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confidence: 99%

Postsynaptic protein assembly in three- and two-dimensions studied by mesoscopic simulations

Yamada

Takada

2023

Preprint

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Postsynaptic density (PSD) is a protein condensate located under the postsynaptic membrane that influences the localization of glutamate receptors and thus contributes to synaptic plasticity. Recent in vitro studies have revealed the formation of droplets of various soluble PSD proteins via liquid-liquid phase separation. However, it is unclear how these protein condensates are formed beneath the membrane and how they specifically affect the localization of glutamate receptors in the membrane. In this study, focusing on the mixture of a glutamate receptor complex, AMPAR-TARP, and a ubiquitous scaffolding protein, PSD-95, we constructed a mesoscopic model of protein-domain interactions in PSD and performed comparative molecular simulations. The results showed a sharp contrast in the phase behaviors of protein assemblies in three-dimension (3D) and those under the membrane (denoted as 2D). A mixture of a soluble variant of the AMPAR-TARP complex and PSD-95 in the 3D system resulted in a phase-separated condensate, which was consistent with the experimental results. However, with identical domain interactions, AMPAR-TARP embedded in the membrane formed clusters with PSD-95, but did not form a stable separated phase. The results indicate that the phase separation behaviors in the 3D and 2D systems were distinct. Stable phase separation is more difficult to achieve in and beneath the membrane than in 3D systems.

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“…The C-terminus of stargazin (TARP γ2 subunit) and PSD-95 exhibit phase separation at an average concentration of 10 μM (28). In addition, the dissociation constant 𝐾 𝑑 between C-terminus of stargazin and full-length PDZ-95 was measured to be 0.63 ± 0.6 μM (28), 1.2 μM (result from ITC assay), or 2.66 ± 0.07 μM (result from FP saturation assay) (41). We assumed the experimental 𝐾 𝑑 to be 1.0 μM.…”

Section: Resultsmentioning

confidence: 99%