1
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Brugger C, Schwartz J, Novick S, Tong S, Hoskins JR, Majdalani N, Kim R, Filipovski M, Wickner S, Gottesman S, Griffin PR, Deaconescu AM. Structure of phosphorylated-like RssB, the adaptor delivering σ s to the ClpXP proteolytic machinery, reveals an interface switch for activation. J Biol Chem 2023; 299:105440. [PMID: 37949227 PMCID: PMC10755785 DOI: 10.1016/j.jbc.2023.105440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/15/2023] [Accepted: 10/18/2023] [Indexed: 11/12/2023] Open
Abstract
In enterobacteria such as Escherichia coli, the general stress response is mediated by σs, the stationary phase dissociable promoter specificity subunit of RNA polymerase. σs is degraded by ClpXP during active growth in a process dependent on the RssB adaptor, which is thought to be stimulated by the phosphorylation of a conserved aspartate in its N-terminal receiver domain. Here we present the crystal structure of full-length RssB bound to a beryllofluoride phosphomimic. Compared to the structure of RssB bound to the IraD anti-adaptor, our new RssB structure with bound beryllofluoride reveals conformational differences and coil-to-helix transitions in the C-terminal region of the RssB receiver domain and in the interdomain segmented helical linker. These are accompanied by masking of the α4-β5-α5 (4-5-5) "signaling" face of the RssB receiver domain by its C-terminal domain. Critically, using hydrogen-deuterium exchange mass spectrometry, we identify σs-binding determinants on the 4-5-5 face, implying that this surface needs to be unmasked to effect an interdomain interface switch and enable full σs engagement and hand-off to ClpXP. In activated receiver domains, the 4-5-5 face is often the locus of intermolecular interactions, but its masking by intramolecular contacts upon phosphorylation is unusual, emphasizing that RssB is a response regulator that undergoes atypical regulation.
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Affiliation(s)
- Christiane Brugger
- Laboratories of Molecular Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Jacob Schwartz
- Laboratories of Molecular Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Scott Novick
- Department of Molecular Medicine, The Wertheim UF Scripps Institute for Biomedical Innovation and Technology, University of Florida, Jupiter, Florida, USA
| | - Song Tong
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Joel R Hoskins
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Nadim Majdalani
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Rebecca Kim
- Laboratories of Molecular Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Martin Filipovski
- Laboratories of Molecular Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Sue Wickner
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Susan Gottesman
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Patrick R Griffin
- Department of Molecular Medicine, The Wertheim UF Scripps Institute for Biomedical Innovation and Technology, University of Florida, Jupiter, Florida, USA
| | - Alexandra M Deaconescu
- Laboratories of Molecular Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA.
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2
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Patel S, Bhatt AM, Bhansali P, Setty SRG. Pseudophosphatase STYXL1 depletion enhances glucocerebrosidase trafficking to lysosomes via ER stress. Traffic 2023; 24:254-269. [PMID: 37198709 DOI: 10.1111/tra.12886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 05/19/2023]
Abstract
Pseudophosphatases are catalytically inactive but share sequence and structural similarities with classical phosphatases. STYXL1 is a pseudophosphatase that belongs to the family of dual-specificity phosphatases and is known to regulate stress granule formation, neurite formation and apoptosis in different cell types. However, the role of STYXL1 in regulating cellular trafficking or the lysosome function has not been elucidated. Here, we show that the knockdown of STYXL1 enhances the trafficking of β-glucocerebrosidase (β-GC) and its lysosomal activity in HeLa cells. Importantly, the STYXL1-depleted cells display enhanced distribution of endoplasmic reticulum (ER), late endosome and lysosome compartments. Further, knockdown of STYXL1 causes the nuclear translocation of unfolded protein response (UPR) and lysosomal biogenesis transcription factors. However, the upregulated β-GC activity in the lysosomes is independent of TFEB/TFE3 nuclear localization in STYXL1 knockdown cells. The treatment of STYXL1 knockdown cells with 4-PBA (ER stress attenuator) significantly reduces the β-GC activity equivalent to control cells but not additive with thapsigargin, an ER stress activator. Additionally, STYXL1-depleted cells show the enhanced contact of lysosomes with ER, possibly via increased UPR. The depletion of STYXL1 in human primary fibroblasts derived from Gaucher patients showed moderately enhanced lysosomal enzyme activity. Overall, these studies illustrated the unique role of pseudophosphatase STYXL1 in modulating the lysosome function both in normal and lysosome-storage disorder cell types. Thus, designing small molecules against STYXL1 possibly can restore the lysosome activity by enhancing ER stress in Gaucher disease.
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Affiliation(s)
- Saloni Patel
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Anshul Milap Bhatt
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Priyanka Bhansali
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Subba Rao Gangi Setty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
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3
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Liu D, Zhang Y, Fang H, Yuan J, Ji L. The progress of research into pseudophosphatases. Front Public Health 2022; 10:965631. [PMID: 36106167 PMCID: PMC9464862 DOI: 10.3389/fpubh.2022.965631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 08/09/2022] [Indexed: 01/24/2023] Open
Abstract
Pseudophosphatases are a class of phosphatases that mutate at the catalytically active site. They play important parts in many life processes and disorders, e.g., cell apoptosis, stress reaction, tumorigenesis, axon differentiation, Charcot-Marie-Tooth, and metabolic dysfunction. The present review considers the structures and action types of pseudophosphatases in four families, protein tyrosine phosphatases (PTPs), myotube protein phosphatases (MTMs), phosphatases and tensin homologues (PTENs) and dual specificity phosphatases (DUSPs), as well as their mechanisms in signaling and disease. We aimed to provide reference material for the research and treatment of related diseases.
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Affiliation(s)
- Deqiang Liu
- College of Life Sciences, Shandong Normal University, Jinan, China
| | - Yiming Zhang
- College of Life Sciences, Shandong Normal University, Jinan, China
| | - Hui Fang
- College of Life Sciences, Shandong Normal University, Jinan, China
| | - Jinxiang Yuan
- College of Life Sciences, Shandong Normal University, Jinan, China,The Collaborative Innovation Center, Jining Medical University, Jining, China,*Correspondence: Jinxiang Yuan
| | - Lizhen Ji
- College of Life Sciences, Shandong Normal University, Jinan, China,Lizhen Ji
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4
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Hepworth EMW, Hinton SD. Pseudophosphatases as Regulators of MAPK Signaling. Int J Mol Sci 2021; 22:12595. [PMID: 34830476 DOI: 10.3390/ijms222212595] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 01/03/2023] Open
Abstract
Mitogen-activated protein kinase (MAPK) signaling pathways are highly conserved regulators of eukaryotic cell function. These enzymes regulate many biological processes, including the cell cycle, apoptosis, differentiation, protein biosynthesis, and oncogenesis; therefore, tight control of the activity of MAPK is critical. Kinases and phosphatases are well established as MAPK activators and inhibitors, respectively. Kinases phosphorylate MAPKs, initiating and controlling the amplitude of the activation. In contrast, MAPK phosphatases (MKPs) dephosphorylate MAPKs, downregulating and controlling the duration of the signal. In addition, within the past decade, pseudoenzymes of these two families, pseudokinases and pseudophosphatases, have emerged as bona fide signaling regulators. This review discusses the role of pseudophosphatases in MAPK signaling, highlighting the function of phosphoserine/threonine/tyrosine-interacting protein (STYX) and TAK1-binding protein (TAB 1) in regulating MAPKs. Finally, a new paradigm is considered for this well-studied cellular pathway, and signal transduction pathways in general.
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5
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Kozlov G, Funato Y, Chen YS, Zhang Z, Illes K, Miki H, Gehring K. PRL3 pseudophosphatase activity is necessary and sufficient to promote metastatic growth. J Biol Chem 2020; 295:11682-11692. [PMID: 32571875 PMCID: PMC7450121 DOI: 10.1074/jbc.ra120.014464] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/17/2020] [Indexed: 01/07/2023] Open
Abstract
Phosphatases of regenerating liver (PRLs) are markers of cancer and promote tumor growth. They have been implicated in a variety of biochemical pathways but the physiologically relevant target of phosphatase activity has eluded 20 years of investigation. Here, we show that PRL3 catalytic activity is not required in a mouse model of metastasis. PRL3 binds and inhibits CNNM4, a membrane protein associated with magnesium transport. Analysis of PRL3 mutants specifically defective in either CNNM-binding or phosphatase activity demonstrate that CNNM binding is necessary and sufficient to promote tumor metastasis. As PRLs do have phosphatase activity, they are in fact pseudo-pseudophosphatases. Phosphatase activity leads to formation of phosphocysteine, which blocks CNNM binding and may play a regulatory role. We show levels of PRL cysteine phosphorylation vary in response to culture conditions and in different tissues. Examination of related protein phosphatases shows the stability of phosphocysteine is a unique and evolutionarily conserved property of PRLs. The demonstration that PRL3 functions as a pseudophosphatase has important ramifications for the design of PRL inhibitors for cancer.
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Affiliation(s)
- Guennadi Kozlov
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montreal, Quebec, Canada
| | - Yosuke Funato
- Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Yu Seby Chen
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montreal, Quebec, Canada
| | - Zhidian Zhang
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montreal, Quebec, Canada
| | - Katalin Illes
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montreal, Quebec, Canada
| | - Hiroaki Miki
- Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Kalle Gehring
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montreal, Quebec, Canada, For correspondence: Kalle Gehring,
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6
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Hinton SD. Pseudophosphatase MK-STYX: the atypical member of the MAP kinase phosphatases. FEBS J 2020; 287:4221-4231. [PMID: 32472731 DOI: 10.1111/febs.15426] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/25/2020] [Accepted: 05/26/2020] [Indexed: 01/03/2023]
Abstract
The regulation of the phosphorylation of mitogen-activated protein kinases (MAPKs) is essential for cellular processes such as proliferation, differentiation, survival, and death. Mutations within the MAPK signaling cascades are implicated in diseases such as cancer, neurodegenerative disorders, arthritis, obesity, and diabetes. MAPK phosphorylation is controlled by an intricate balance between MAPK kinases (enzymes that add phosphate groups) and MAPK phosphatases (MKPs) (enzymes that remove phosphate groups). MKPs are complex negative regulators of the MAPK pathway that control the amplitude and spatiotemporal regulation of MAPKs. MK-STYX (MAPK phosphoserine/threonine/tyrosine-binding protein) is a member of the MKP subfamily, which lacks the critical histidine and nucleophilic cysteine residues in the active site required for catalysis. MK-STYX does not influence the phosphorylation status of MAPK, but even so it adds to the complexity of signal transduction cascades as a signaling regulator. This review highlights the function of MK-STYX, providing insight into MK-STYX as a signal regulating molecule in the stress response, HDAC 6 dynamics, apoptosis, and neurite differentiation.
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Affiliation(s)
- Shantá D Hinton
- Department of Biology, Integrated Science Center, William & Mary, Williamsburg, VA, USA
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7
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Reiterer V, Pawłowski K, Desrochers G, Pause A, Sharpe HJ, Farhan H. The dead phosphatases society: a review of the emerging roles of pseudophosphatases. FEBS J 2020; 287:4198-4220. [PMID: 32484316 DOI: 10.1111/febs.15431] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 05/12/2020] [Accepted: 05/27/2020] [Indexed: 12/11/2022]
Abstract
Phosphatases are a diverse family of enzymes, comprising at least 10 distinct protein folds. Like most other enzyme families, many have sequence variations that predict an impairment or loss of catalytic activity classifying them as pseudophosphatases. Research on pseudoenzymes is an emerging area of interest, with new biological functions repurposed from catalytically active relatives. Here, we provide an overview of the pseudophosphatases identified to date in all major phosphatase families. We will highlight the degeneration of the various catalytic sequence motifs and discuss the challenges associated with the experimental determination of catalytic inactivity. We will also summarize the role of pseudophosphatases in various diseases and discuss the major challenges and future directions in this field.
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Affiliation(s)
| | | | - Guillaume Desrochers
- Department of Biochemistry, McGill University, Montréal, QC, Canada.,Goodman Cancer Research Centre, McGill University, Montréal, QC, Canada
| | - Arnim Pause
- Department of Biochemistry, McGill University, Montréal, QC, Canada.,Goodman Cancer Research Centre, McGill University, Montréal, QC, Canada
| | | | - Hesso Farhan
- Institute of Basic Medical Sciences, University of Oslo, Norway
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8
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Cao Y, Banks DA, Mattei AM, Riddick AT, Reed KM, Zhang AM, Pickering ES, Hinton SD. Pseudophosphatase MK-STYX Alters Histone Deacetylase 6 Cytoplasmic Localization, Decreases Its Phosphorylation, and Increases Detyrosination of Tubulin. Int J Mol Sci 2019; 20:ijms20061455. [PMID: 30909412 PMCID: PMC6470616 DOI: 10.3390/ijms20061455] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/14/2019] [Accepted: 03/19/2019] [Indexed: 12/14/2022] Open
Abstract
The catalytically inactive mitogen-activated protein (MAP) kinase phosphatase, MK-STYX (MAPK (mitogen-activated protein kinase) phosphoserine/threonine/tyrosine-binding protein) interacts with the stress granule nucleator G3BP-1 (Ras-GAP (GTPase-activating protein) SH3 (Src homology 3) domain-binding protein-1), and decreases stress granule (stalled mRNA) formation. Histone deacetylase isoform 6 (HDAC6) also binds G3BP-1 and serves as a major component of stress granules. The discovery that MK-STYX and HDAC6 both interact with G3BP-1 led us to investigate the effects of MK-STYX on HDAC6 dynamics. In control HEK/293 cells, HDAC6 was cytosolic, as expected, and formed aggregates under conditions of stress. In contrast, in cells overexpressing MK-STYX, HDAC6 was both nuclear and cytosolic and the number of stress-induced aggregates significantly decreased. Immunoblots showed that MK-STYX decreases HDAC6 serine phosphorylation, protein tyrosine phosphorylation, and lysine acetylation. HDAC6 is known to regulate microtubule dynamics to form aggregates. MK-STYX did not affect the organization of microtubules, but did affect their post-translational modification. Tubulin acetylation was increased in the presence of MK-STYX. In addition, the detyrosination of tubulin was significantly increased in the presence of MK-STYX. These findings show that MK-STYX decreases the number of HDAC6-containing aggregates and alters their localization, sustains microtubule acetylation, and increases detyrosination of microtubules, implicating MK-STYX as a signaling molecule in HDAC6 activity.
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Affiliation(s)
- Yuming Cao
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA 23185, USA.
| | - Dallas A Banks
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA 23185, USA.
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA.
| | - Andrew M Mattei
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA 23185, USA.
| | - Alexys T Riddick
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA 23185, USA.
| | - Kirstin M Reed
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA 23185, USA.
| | - Ashley M Zhang
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA 23185, USA.
| | - Emily S Pickering
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA 23185, USA.
| | - Shantá D Hinton
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA 23185, USA.
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9
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Banks DA, Dahal A, McFarland AG, Flowers BM, Stephens CA, Swack B, Gugssa A, Anderson WA, Hinton SD. MK-STYX Alters the Morphology of Primary Neurons, and Outgrowths in MK-STYX Overexpressing PC-12 Cells Develop a Neuronal Phenotype. Front Mol Biosci 2017; 4:76. [PMID: 29250526 PMCID: PMC5715325 DOI: 10.3389/fmolb.2017.00076] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 11/02/2017] [Indexed: 01/14/2023] Open
Abstract
We previously reported that the pseudophosphatase MK-STYX (mitogen activated kinase phosphoserine/threonine/tyrosine binding protein) dramatically increases the number of what appeared to be primary neurites in rat pheochromocytoma (PC-12) cells; however, the question remained whether these MK-STYX-induced outgrowths were bona fide neurites, and formed synapses. Here, we report that microtubules and microfilaments, components of the cytoskeleton that are involved in the formation of neurites, are present in MK-STYX-induced outgrowths. In addition, in response to nerve growth factor (NGF), MK-STYX-expressing cells produced more growth cones than non-MK-STYX-expressing cells, further supporting a model in which MK-STYX has a role in actin signaling. Furthermore, immunoblot analysis demonstrates that MK-STYX modulates actin expression. Transmission electron microscopy confirmed that MK-STYX-induced neurites form synapses. To determine whether these MK-STYX-induced neurites have pre-synaptic or post-synaptic properties, we used classical markers for axons and dendrites, Tau-1 and MAP2 (microtubule associated protein 2), respectively. MK-STYX induced neurites were dopaminergic and expression of both Tau-1 and MAP2 suggests that they have both axonal and dendritic properties. Further studies in rat hippocampal primary neurons demonstrated that MK-STYX altered their morphology. A significant number of primary neurons in the presence of MK-STYX had more than the normal number of primary neurites. Our data illustrate the novel findings that MK-STYX induces outgrowths in PC-12 cells that fit the criteria for neurites, have a greater number of growth cones, form synapses, and have pre-synaptic and post-synaptic properties. It also highlights that the pseudophosphatase MK-STYX significantly alters the morphology of primary neurons.
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Affiliation(s)
- Dallas A Banks
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA, United States
| | - Arya Dahal
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA, United States
| | - Alexander G McFarland
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA, United States
| | - Brittany M Flowers
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA, United States.,National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Christina A Stephens
- Department of Chemistry, Integrated Science Center, College of William and Mary, Williamsburg, VA, United States
| | - Benjamin Swack
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA, United States
| | - Ayele Gugssa
- Department of Biology, Howard University, Washington, DC, United States
| | | | - Shantá D Hinton
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA, United States
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10
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Reiterer V, Pawłowski K, Farhan H. STYX: a versatile pseudophosphatase. Biochem Soc Trans 2017; 45:449-56. [PMID: 28408485 DOI: 10.1042/BST20160279] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 02/16/2017] [Accepted: 02/20/2017] [Indexed: 01/12/2023]
Abstract
The pseudophosphatase STYX (serine/threonine/tyrosine interacting protein) is a catalytically inactive member of the protein tyrosine phosphatase family. We perform a phylogenetic analysis of STYX and ask how far does the pseudoenzyme status of STYX reaches in evolution. Based on our previous work, we use STYX as a showcase to discuss four basic modes of action that any given pseudoenzyme may exert. Our previous work on the effect of STYX on mitogen-activated protein kinase (MAPK) signaling led us to identify two complementary modes of action. On the one hand, STYX competes with active phosphatases for binding to MAPKs. On the other hand, STYX acts as a nuclear anchor for MAPKs, affecting their nucleo-cytoplasmic shuttling. Finally, we discuss our recent work on the regulation of FBXW7 by this pseudophosphatase and how it affects the ubiquitylation and degradation of its substrates. We discuss the biological significance of this regulatory mechanism and use it as an example for the versatility of pseudoenzymes that may divert away from merely regulating their active homologs.
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11
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Murphy JM, Farhan H, Eyers PA. Bio-Zombie: the rise of pseudoenzymes in biology. Biochem Soc Trans 2017; 45:537-544. [PMID: 28408493 DOI: 10.1042/bst20160400] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 02/19/2017] [Accepted: 02/21/2017] [Indexed: 11/17/2022]
Abstract
Pseudoenzymes are catalytically dead counterparts of enzymes. Despite their first description some 50 years ago, the importance and functional diversity of these 'fit-for-purpose' polypeptides is only now being appreciated. Pseudoenzymes have been identified throughout all the kingdoms of life and, owing to predicted deficits in enzyme activity due to the absence of catalytic residues, have been variously referred to as pseudoenzymes, non-enzymes, dead enzymes, prozymes or 'zombie' proteins. An important goal of the recent Biochemical Society Pseudoenzymes-focused meeting was to explore the functional and evolutionary diversity of pseudoenzymes and to begin to evaluate their functions in biology, including cell signalling and metabolism. Here, we summarise the impressive breadth of enzyme classes that are known to have pseudoenzyme counterparts and present examples of known cellular functions. We predict that the next decades will represent golden years for the analysis of pseudoenzymes.
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Affiliation(s)
- James M Murphy
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Hesso Farhan
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, U.K.
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12
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Reiterer V, Figueras-Puig C, Le Guerroue F, Confalonieri S, Vecchi M, Jalapothu D, Kanse SM, Deshaies RJ, Di Fiore PP, Behrends C, Farhan H. The pseudophosphatase STYX targets the F-box of FBXW7 and inhibits SCFFBXW7 function. EMBO J 2016; 36:260-273. [PMID: 28007894 DOI: 10.15252/embj.201694795] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 11/11/2016] [Accepted: 11/17/2016] [Indexed: 11/09/2022] Open
Abstract
The F-box protein FBXW7 is the substrate-recruiting subunit of an SCF ubiquitin ligase and a major tumor-suppressor protein that is altered in several human malignancies. Loss of function of FBXW7 results in the stabilization of numerous proteins that orchestrate cell proliferation and survival. Little is known about proteins that directly regulate the function of this protein. In the current work, we have mapped the interactome of the enigmatic pseudophosphatase STYX We reasoned that a catalytically inactive phosphatase might have adopted novel mechanisms of action. The STYX interactome contained several F-box proteins, including FBXW7. We show that STYX binds to the F-box domain of FBXW7 and disables its recruitment into the SCF complex. Therefore, STYX acts as a direct inhibitor of FBXW7, affecting the cellular levels of its substrates. Furthermore, we find that levels of STYX and FBXW7 are anti-correlated in breast cancer patients, which affects disease prognosis. We propose the STYX-FBXW7 interaction as a promising drug target for future investigations.
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Affiliation(s)
- Veronika Reiterer
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Biotechnology Institute Thurgau, Kreuzlingen, Switzerland
| | | | - Francois Le Guerroue
- Institute of Biochemistry II, Medical School Goethe University, Frankfurt, Germany
| | - Stefano Confalonieri
- The FIRC Institute for Molecular Oncology, IFOM, Milan, Italy.,Molecular Medicine Program, European Institute of Oncology, Milan, Italy
| | - Manuela Vecchi
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
| | | | - Sandip M Kanse
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Raymond J Deshaies
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
| | - Pier Paolo Di Fiore
- The FIRC Institute for Molecular Oncology, IFOM, Milan, Italy.,Molecular Medicine Program, European Institute of Oncology, Milan, Italy.,Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | - Christian Behrends
- Institute of Biochemistry II, Medical School Goethe University, Frankfurt, Germany .,Munich Cluster for Systems Neurology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Hesso Farhan
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway .,Biotechnology Institute Thurgau, Kreuzlingen, Switzerland.,Department of Biology, University of Konstanz, Konstanz, Germany
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Reiterer V, Eyers PA, Farhan H. Day of the dead: pseudokinases and pseudophosphatases in physiology and disease. Trends Cell Biol 2014; 24:489-505. [PMID: 24818526 DOI: 10.1016/j.tcb.2014.03.008] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 12/19/2022]
Abstract
Pseudophosphatases and pseudokinases are increasingly viewed as integral elements of signaling pathways, and there is mounting evidence that they have frequently retained the ability to interact with cellular 'substrates', and can exert important roles in different diseases. However, these pseudoenzymes have traditionally received scant attention compared to classical kinases and phosphatases. In this review we explore new findings in the emerging pseudokinase and pseudophosphatase fields, and discuss their different modes of action which include exciting new roles as scaffolds, anchors, spatial modulators, traps, and ligand-driven regulators of canonical kinases and phosphatases. Thus, it is now apparent that pseudokinases and pseudophosphatases both support and drive a panoply of signaling networks. Finally, we highlight recent evidence on their involvement in human pathologies, marking them as potential novel drug targets.
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Affiliation(s)
- Veronika Reiterer
- Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland
| | - Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
| | - Hesso Farhan
- Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland; Department of Biology, University of Konstanz, Konstanz, Germany.
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