1
|
Vish KJ, Stiegler AL, Boggon TJ. Diverse p120RasGAP interactions with doubly phosphorylated partners EphB4, p190RhoGAP, and Dok1. J Biol Chem 2023; 299:105098. [PMID: 37507023 PMCID: PMC10470053 DOI: 10.1016/j.jbc.2023.105098] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 05/10/2023] [Revised: 07/06/2023] [Accepted: 07/24/2023] [Indexed: 07/30/2023] Open
Abstract
RasGAP (p120RasGAP), the founding member of the GTPase-activating protein (GAP) family, is one of only nine human proteins to contain two SH2 domains and is essential for proper vascular development. Despite its importance, its interactions with key binding partners remains unclear. In this study we provide a detailed viewpoint of RasGAP recruitment to various binding partners and assess their impact on RasGAP activity. We reveal the RasGAP SH2 domains generate distinct binding interactions with three well-known doubly phosphorylated binding partners: p190RhoGAP, Dok1, and EphB4. Affinity measurements demonstrate a 100-fold weakened affinity for RasGAP-EphB4 binding compared to RasGAP-p190RhoGAP or RasGAP-Dok1 binding, possibly driven by single versus dual SH2 domain engagement with a dominant N-terminal SH2 interaction. Small-angle X-ray scattering reveals conformational differences between RasGAP-EphB4 binding and RasGAP-p190RhoGAP binding. Importantly, these interactions do not impact catalytic activity, implying RasGAP utilizes its SH2 domains to achieve diverse spatial-temporal regulation of Ras signaling in a previously unrecognized fashion.
Collapse
Affiliation(s)
- Kimberly J Vish
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Amy L Stiegler
- Department of Pharmacology, Yale University, New Haven, Connecticut, USA
| | - Titus J Boggon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA; Department of Pharmacology, Yale University, New Haven, Connecticut, USA; Department of Yale Cancer Center, Yale University, New Haven, Connecticut, USA.
| |
Collapse
|
2
|
Héraud C, Pinault M, Neaud V, Saltel F, Lagrée V, Moreau V. Identification of an inhibitory domain in GTPase-activating protein p190RhoGAP responsible for masking its functional GAP domain. J Biol Chem 2022; 299:102792. [PMID: 36516886 PMCID: PMC9840978 DOI: 10.1016/j.jbc.2022.102792] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 11/22/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
The GTPase-activating protein (GAP) p190RhoGAP (p190A) is encoded by ARHGAP35 which is found mutated in cancers. p190A is a negative regulator of the GTPase RhoA in cells and must be targeted to RhoA-dependent actin-based structures to fulfill its roles. We previously identified a functional region of p190A called the PLS (protrusion localization sequence) required for localization of p190A to lamellipodia but also for regulating the GAP activity of p190A. Additional effects of the PLS region on p190A localization and activity need further characterization. Here, we demonstrated that the PLS is required to target p190A to invadosomes. Cellular expression of a p190A construct devoid of the PLS (p190AΔPLS) favored RhoA inactivation in a stronger manner than WT p190A, suggesting that the PLS is an autoinhibitory domain of p190A GAP activity. To decipher this mechanism, we searched for PLS-interacting proteins using a two-hybrid screen. We found that the PLS can interact with p190A itself. Coimmunoprecipitation experiments demonstrated that the PLS interacts with a region in close proximity to the GAP domain. Furthermore, we demonstrated that this interaction is abolished if the PLS harbors cancer-associated mutations: the S866F point mutation and the Δ865-870 deletion. Our results are in favor of defining PLS as an inhibitory domain responsible for masking the p190A functional GAP domain. Thus, p190A could exist in cells under two forms: an inactive closed conformation with a masked GAP domain and an open conformation allowing p190A GAP function. Altogether, our data unveil a new mechanism of p190A regulation.
Collapse
|
3
|
Agyemang K, Johansen AM, Barker GW, Pennison MJ, Sheffield K, Jimenez H, Blackman C, Sharma S, Fordjour PA, Singh R, Cook KL, Lin HK, Zhang W, Lo HW, Watabe K, Sun P, Langefeld CD, Pasche B. TGFBR1*6A as a modifier of breast cancer risk and progression: advances and future prospects. NPJ Breast Cancer 2022; 8:84. [PMID: 35853889 DOI: 10.1038/s41523-022-00446-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 06/13/2022] [Indexed: 11/18/2022] Open
Abstract
There is growing evidence that germline mutations in certain genes influence cancer susceptibility, tumor evolution, as well as clinical outcomes. Identification of a disease-causing genetic variant enables testing and diagnosis of at-risk individuals. For breast cancer, several genes such as BRCA1, BRCA2, PALB2, ATM, and CHEK2 act as high- to moderate-penetrance cancer susceptibility genes. Genotyping of these genes informs genetic risk assessment and counseling, as well as treatment and management decisions in the case of high-penetrance genes. TGFBR1*6A (rs11466445) is a common variant of the TGF-β receptor type I (TGFBR1) that has a global minor allelic frequency (MAF) of 0.051 according to the 1000 Genomes Project Consortium. It is emerging as a high frequency, low penetrance tumor susceptibility allele associated with increased cancer risk among several cancer types. The TGFBR1*6A allele has been associated with increased breast cancer risk in women, OR 1.15 (95% CI 1.01–1.31). Functionally, TGFBR1*6A promotes breast cancer cell proliferation, migration, and invasion through the regulation of the ERK pathway and Rho-GTP activation. This review discusses current findings on the genetic, functional, and mechanistic associations between TGFBR1*6A and breast cancer risk and proposes future directions as it relates to genetic association studies and mechanisms of action for tumor growth, metastasis, and immune suppression.
Collapse
|
4
|
Meng Z, Li FL, Fang C, Yeoman B, Qiu Y, Wang Y, Cai X, Lin KC, Yang D, Luo M, Fu V, Ma X, Diao Y, Giancotti FG, Ren B, Engler AJ, Guan KL. The Hippo pathway mediates Semaphorin signaling. Sci Adv 2022; 8:eabl9806. [PMID: 35613278 PMCID: PMC9132450 DOI: 10.1126/sciadv.abl9806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 04/11/2022] [Indexed: 02/05/2023]
Abstract
Semaphorins were originally identified as axonal guidance molecules, but they also control processes such as vascular development and tumorigenesis. The downstream signaling cascades of Semaphorins in these biological processes remain unclear. Here, we show that the class 3 Semaphorins (SEMA3s) activate the Hippo pathway to attenuate tissue growth, angiogenesis, and tumorigenesis. SEMA3B restoration in lung cancer cells with SEMA3B loss of heterozygosity suppresses cancer cell growth via activating the core Hippo kinases LATS1/2 (large tumor suppressor kinase 1/2). Furthermore, SEMA3 also acts through LATS1/2 to inhibit angiogenesis. We identified p190RhoGAPs as essential partners of the SEMA3A receptor PlexinA in Hippo regulation. Upon SEMA3 treatment, PlexinA interacts with the pseudo-guanosine triphosphatase (GTPase) domain of p190RhoGAP and simultaneously recruits RND GTPases to activate p190RhoGAP, which then stimulates LATS1/2. Disease-associated etiological factors, such as genetic lesions and oscillatory shear, diminish Hippo pathway regulation by SEMA3. Our study thus discovers a critical role of Hippo signaling in mediating SEMA3 physiological function.
Collapse
Affiliation(s)
- Zhipeng Meng
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Sylvester Comprehensive Cancer Center, Miami, FL 33136, USA
| | - Fu-Long Li
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Cao Fang
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Benjamin Yeoman
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yunjiang Qiu
- Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093, USA
- Bioinformatics and Systems Biology Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ying Wang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Sylvester Comprehensive Cancer Center, Miami, FL 33136, USA
| | - Xiaomin Cai
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Kimberly C. Lin
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Di Yang
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Min Luo
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Vivian Fu
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Xiaoxiao Ma
- Center for Immunotherapy and Precision Immuno-Oncology, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Yarui Diao
- Regeneration Next Initiative, Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Filippo G. Giancotti
- Department of Cancer Biology and David H. Koch Center for Applied Research of GU Cancers, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Herbert Irving Comprehensive Cancer Center and Department of Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10033, USA
| | - Bing Ren
- Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093, USA
| | - Adam J. Engler
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| |
Collapse
|
5
|
Abstract
Pseudoenzymes are emerging as significant mediators and regulators of signal transduction. These proteins maintain enzyme folds and topologies, but are disrupted in the conserved motifs required for enzymatic activity. Among the pseudoenzymes, the pseudoGTPase group of atypical GTPases has recently expanded and includes the Rnd and RGK groups, RhoH and the RhoBTB proteins, mitochondrial RhoGTPase and centaurin-γ groups, CENP-M, dynein LIC, Entamoeba histolytica RabX3, leucine-rich repeat kinase 2, and the p190RhoGAP proteins. The wide range of cellular functions associated with pseudoGTPases includes cell migration and adhesion, membrane trafficking and cargo transport, mitosis, mitochondrial activity, transcriptional control, and autophagy, placing the group in an expanding portfolio of signaling pathways. In this review, we examine how the pseudoGTPases differ from canonical GTPases and consider their mechanistic and functional roles in signal transduction. We review the amino acid differences between the pseudoGTPases and discuss how these proteins can be classified based on their ability to bind nucleotide and their enzymatic activity. We discuss the molecular and structural consequences of amino acid divergence from canonical GTPases and use comparison with the well-studied pseudokinases to illustrate the classifications. PseudoGTPases are fast becoming recognized as important mechanistic components in a range of cellular roles, and we provide a concise discussion of the currently identified members of this group. ENZYMES: small GTPases; EC number: EC 3.6.5.2.
Collapse
Affiliation(s)
- Amy L. Stiegler
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520, USA
| | - Titus J. Boggon
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520, USA
- Departments of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520, USA
- Yale Cancer Center, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520, USA
| |
Collapse
|
6
|
Jaber Chehayeb R, Stiegler AL, Boggon TJ. Crystal structures of p120RasGAP N-terminal SH2 domain in its apo form and in complex with a p190RhoGAP phosphotyrosine peptide. PLoS One 2019; 14:e0226113. [PMID: 31891593 PMCID: PMC6938330 DOI: 10.1371/journal.pone.0226113] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 11/19/2019] [Indexed: 01/26/2023] Open
Abstract
The Rho and Ras pathways play vital roles in cell growth, division and motility. Cross-talk between the pathways amplifies their roles in cell proliferation and motility and its dysregulation is involved in disease pathogenesis. One important interaction for cross-talk occurs between p120RasGAP (RASA1), a GTPase activating protein (GAP) for Ras, and p190RhoGAP (p190RhoGAP-A, ARHGAP35), a GAP for Rho. The binding of these proteins is primarily mediated by two SH2 domains within p120RasGAP engaging phosphorylated tyrosines of p190RhoGAP, of which the best studied is pTyr-1105. To better understand the interaction between p120RasGAP and p190RhoGAP, we determined the 1.75 Å X-ray crystal structure of the N-terminal SH2 domain of p120RasGAP in the unliganded form, and its 1.6 Å co-crystal structure in complex with a synthesized phosphotyrosine peptide, EEENI(p-Tyr)SVPHDST, corresponding to residues 1100–1112 of p190RhoGAP. We find that the N-terminal SH2 domain of p120RhoGAP has the characteristic SH2 fold encompassing a central beta-sheet flanked by two alpha-helices, and that peptide binding stabilizes specific conformations of the βE-βF loop and arginine residues R212 and R231. Site-directed mutagenesis and native gel shifts confirm phosphotyrosine binding through the conserved FLVR motif arginine residue R207, and isothermal titration calorimetry finds a dissociation constant of 0.3 ± 0.1 μM between the phosphopeptide and SH2 domain. These results demonstrate that the major interaction between two important GAP proteins, p120RasGAP and p190RhoGAP, is mediated by a canonical SH2-pTyr interaction.
Collapse
Affiliation(s)
- Rachel Jaber Chehayeb
- Yale College, New Haven, Connecticut, United States of America
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Amy L. Stiegler
- Department of Pharmacology, Yale University, New Haven, Connecticut, United States of America
| | - Titus J. Boggon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Department of Pharmacology, Yale University, New Haven, Connecticut, United States of America
- Yale Cancer Center, Yale University, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
7
|
Ribeiro AJM, Das S, Dawson N, Zaru R, Orchard S, Thornton JM, Orengo C, Zeqiraj E, Murphy JM, Eyers PA. Emerging concepts in pseudoenzyme classification, evolution, and signaling. Sci Signal 2019; 12:eaat9797. [PMID: 31409758 DOI: 10.1126/scisignal.aat9797] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The 21st century is witnessing an explosive surge in our understanding of pseudoenzyme-driven regulatory mechanisms in biology. Pseudoenzymes are proteins that have sequence homology with enzyme families but that are proven or predicted to lack enzyme activity due to mutations in otherwise conserved catalytic amino acids. The best-studied pseudoenzymes are pseudokinases, although examples from other families are emerging at a rapid rate as experimental approaches catch up with an avalanche of freely available informatics data. Kingdom-wide analysis in prokaryotes, archaea and eukaryotes reveals that between 5 and 10% of proteins that make up enzyme families are pseudoenzymes, with notable expansions and contractions seemingly associated with specific signaling niches. Pseudoenzymes can allosterically activate canonical enzymes, act as scaffolds to control assembly of signaling complexes and their localization, serve as molecular switches, or regulate signaling networks through substrate or enzyme sequestration. Molecular analysis of pseudoenzymes is rapidly advancing knowledge of how they perform noncatalytic functions and is enabling the discovery of unexpected, and previously unappreciated, functions of their intensively studied enzyme counterparts. Notably, upon further examination, some pseudoenzymes have previously unknown enzymatic activities that could not have been predicted a priori. Pseudoenzymes can be targeted and manipulated by small molecules and therefore represent new therapeutic targets (or anti-targets, where intervention should be avoided) in various diseases. In this review, which brings together broad bioinformatics and cell signaling approaches in the field, we highlight a selection of findings relevant to a contemporary understanding of pseudoenzyme-based biology.
Collapse
Affiliation(s)
- António J M Ribeiro
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Sayoni Das
- Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Natalie Dawson
- Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Rossana Zaru
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Sandra Orchard
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Janet M Thornton
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Christine Orengo
- Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Elton Zeqiraj
- Astbury Centre for Structural Molecular Biology, Molecular and Cellular Biology, Faculty of Biological Sciences, Astbury Building, Room 8.109, University of Leeds, Leeds LS2 9JT, UK
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
| |
Collapse
|
8
|
Héraud C, Pinault M, Lagrée V, Moreau V. p190RhoGAPs, the ARHGAP35- and ARHGAP5-Encoded Proteins, in Health and Disease. Cells 2019; 8:cells8040351. [PMID: 31013840 PMCID: PMC6523970 DOI: 10.3390/cells8040351] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/05/2019] [Accepted: 04/09/2019] [Indexed: 12/30/2022] Open
Abstract
Small guanosine triphosphatases (GTPases) gathered in the Rat sarcoma (Ras) superfamily represent a large family of proteins involved in several key cellular mechanisms. Within the Ras superfamily, the Ras homolog (Rho) family is specialized in the regulation of actin cytoskeleton-based mechanisms. These proteins switch between an active and an inactive state, resulting in subsequent inhibiting or activating downstream signals, leading finally to regulation of actin-based processes. The On/Off status of Rho GTPases implicates two subsets of regulators: GEFs (guanine nucleotide exchange factors), which favor the active GTP (guanosine triphosphate) status of the GTPase and GAPs (GTPase activating proteins), which inhibit the GTPase by enhancing the GTP hydrolysis. In humans, the 20 identified Rho GTPases are regulated by over 70 GAP proteins suggesting a complex, but well-defined, spatio-temporal implication of these GAPs. Among the quite large number of RhoGAPs, we focus on p190RhoGAP, which is known as the main negative regulator of RhoA, but not exclusively. Two isoforms, p190A and p190B, are encoded by ARHGAP35 and ARHGAP5 genes, respectively. We describe here the function of each of these isoforms in physiological processes and sum up findings on their role in pathological conditions such as neurological disorders and cancers.
Collapse
Affiliation(s)
- Capucine Héraud
- INSERM, UMR1053 Bordeaux Research In Translational Oncology, BaRITOn, F-33000 Bordeaux, France.
- University of Bordeaux, UMR1053 Bordeaux Research In Translational Oncology, BaRITOn, Bordeaux F-33000, France.
- Equipe Labellisée Fondation pour la Recherche Médicale (FRM) 2018, 75007 Paris, France.
| | - Mathilde Pinault
- INSERM, UMR1053 Bordeaux Research In Translational Oncology, BaRITOn, F-33000 Bordeaux, France.
- University of Bordeaux, UMR1053 Bordeaux Research In Translational Oncology, BaRITOn, Bordeaux F-33000, France.
- Equipe Labellisée Fondation pour la Recherche Médicale (FRM) 2018, 75007 Paris, France.
| | - Valérie Lagrée
- INSERM, UMR1053 Bordeaux Research In Translational Oncology, BaRITOn, F-33000 Bordeaux, France.
- University of Bordeaux, UMR1053 Bordeaux Research In Translational Oncology, BaRITOn, Bordeaux F-33000, France.
- Equipe Labellisée Fondation pour la Recherche Médicale (FRM) 2018, 75007 Paris, France.
| | - Violaine Moreau
- INSERM, UMR1053 Bordeaux Research In Translational Oncology, BaRITOn, F-33000 Bordeaux, France.
- University of Bordeaux, UMR1053 Bordeaux Research In Translational Oncology, BaRITOn, Bordeaux F-33000, France.
- Equipe Labellisée Fondation pour la Recherche Médicale (FRM) 2018, 75007 Paris, France.
| |
Collapse
|
9
|
Stiegler AL, Boggon TJ. PseudoGTPase domains in p190RhoGAP proteins: a mini-review. Biochem Soc Trans 2018; 46:1713-20. [PMID: 30514771 DOI: 10.1042/BST20180481] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/22/2018] [Accepted: 10/25/2018] [Indexed: 02/07/2023]
Abstract
Pseudoenzymes generally lack detectable catalytic activity despite adopting the overall protein fold of their catalytically competent counterparts, indeed 'pseudo' family members seem to be incorporated in all enzyme classes. The small GTPase enzymes are important signaling proteins, and recent studies have identified many new family members with noncanonical residues within the catalytic cleft, termed pseudoGTPases. To illustrate recent discoveries in the field, we use the p190RhoGAP proteins as an example. p190RhoGAP proteins (ARHGAP5 and ARHGAP35) are the most abundant GTPase activating proteins for the Rho family of small GTPases. These are key regulators of Rho signaling in processes such as cell migration, adhesion and cytokinesis. Structural biology has complemented and guided biochemical analyses for these proteins and has allowed discovery of two cryptic pseudoGTPase domains, and the re-classification of a third, previously identified, GTPase-fold domain as a pseudoGTPase. The three domains within p190RhoGAP proteins illustrate the diversity of this rapidly expanding pseudoGTPase group.
Collapse
|