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DiRusso CJ, Dashtiahangar M, Gilmore TD. Scaffold proteins as dynamic integrators of biological processes. J Biol Chem 2022; 298:102628. [PMID: 36273588 PMCID: PMC9672449 DOI: 10.1016/j.jbc.2022.102628] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 11/15/2022] Open
Abstract
Scaffold proteins act as molecular hubs for the docking of multiple proteins to organize efficient functional units for signaling cascades. Over 300 human proteins have been characterized as scaffolds, acting in a variety of signaling pathways. While the term scaffold implies a static, supportive platform, it is now clear that scaffolds are not simply inert docking stations but can undergo conformational changes that affect their dependent signaling pathways. In this review, we catalog scaffold proteins that have been shown to undergo actionable conformational changes, with a focus on the role that conformational change plays in the activity of the classic yeast scaffold STE5, as well as three human scaffold proteins (KSR, NEMO, SHANK3) that are integral to well-known signaling pathways (RAS, NF-κB, postsynaptic density). We also discuss scaffold protein conformational changes vis-à-vis liquid-liquid phase separation. Changes in scaffold structure have also been implicated in human disease, and we discuss how aberrant conformational changes may be involved in disease-related dysregulation of scaffold and signaling functions. Finally, we discuss how understanding these conformational dynamics will provide insight into the flexibility of signaling cascades and may enhance our ability to treat scaffold-associated diseases.
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Zhang Q, Xiao K, Paredes JM, Mamonova T, Sneddon WB, Liu H, Wang D, Li S, McGarvey JC, Uehling D, Al-Awar R, Joseph B, Jean-Alphonse F, Orte A, Friedman PA. Parathyroid hormone initiates dynamic NHERF1 phosphorylation cycling and conformational changes that regulate NPT2A-dependent phosphate transport. J Biol Chem 2019; 294:4546-4571. [PMID: 30696771 PMCID: PMC6433080 DOI: 10.1074/jbc.ra119.007421] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 01/25/2019] [Indexed: 12/30/2022] Open
Abstract
Na+-H+ exchanger regulatory factor-1 (NHERF1) is a PDZ protein that scaffolds membrane proteins, including sodium-phosphate co-transport protein 2A (NPT2A) at the plasma membrane. NHERF1 is a phosphoprotein with 40 Ser and Thr residues. Here, using tandem MS analysis, we characterized the sites of parathyroid hormone (PTH)-induced NHERF1 phosphorylation and identified 10 high-confidence phosphorylation sites. Ala replacement at Ser46, Ser162, Ser181, Ser269, Ser280, Ser291, Thr293, Ser299, and Ser302 did not affect phosphate uptake, but S290A substitution abolished PTH-dependent phosphate transport. Unexpectedly, Ser290 was rapidly dephosphorylated and rephosphorylated after PTH stimulation, and we found that protein phosphatase 1α (PP1α), which binds NHERF1 through a conserved VxF/W PP1 motif, dephosphorylates Ser290 Mutating 257VPF259 eliminated PP1 binding and blunted dephosphorylation. Tautomycetin blocked PP1 activity and abrogated PTH-sensitive phosphate transport. Using fluorescence lifetime imaging (FLIM), we observed that PTH paradoxically and transiently elevates intracellular phosphate. Added phosphate blocked PP1α-mediated Ser290 dephosphorylation of recombinant NHERF1. Hydrogen-deuterium exchange MS revealed that β-sheets in NHERF1's PDZ2 domain display lower deuterium uptake than those in the structurally similar PDZ1, implying that PDZ1 is more cloistered. Dephosphorylated NHERF1 exhibited faster exchange at C-terminal residues suggesting that NHERF1 dephosphorylation precedes Ser290 rephosphorylation. Our results show that PP1α and NHERF1 form a holoenzyme and that a multiprotein kinase cascade involving G protein-coupled receptor kinase 6A controls the Ser290 phosphorylation status of NHERF1 and regulates PTH-sensitive, NPT2A-mediated phosphate uptake. These findings reveal how reversible phosphorylation modifies protein conformation and function and the biochemical mechanisms underlying PTH control of phosphate transport.
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Affiliation(s)
- Qiangmin Zhang
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - Kunhong Xiao
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology.,Vascular Medicine Institute, and.,Biomedical Mass Spectrometry Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - José M Paredes
- the Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, 18071-Granada, Spain
| | - Tatyana Mamonova
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - W Bruce Sneddon
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - Hongda Liu
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - Dawei Wang
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - Sheng Li
- the Department of Medicine, University of California San Diego, La Jolla, California 92093, and
| | - Jennifer C McGarvey
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology
| | - David Uehling
- the Department of Drug Discovery, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Rima Al-Awar
- the Department of Drug Discovery, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | - Babu Joseph
- the Department of Drug Discovery, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3, Canada
| | | | - Angel Orte
- the Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, 18071-Granada, Spain
| | - Peter A Friedman
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, .,Department of Structural Biology
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