1
|
Pandey M, Sarkar S, Ghosh SK. Ancestral TALE homeobox protein transcription factor regulates actin dynamics and cellular activities of protozoan parasite Entamoeba invadens. Mol Microbiol 2024. [PMID: 38654540 DOI: 10.1111/mmi.15266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 04/26/2024]
Abstract
Entamoeba histolytica causes invasive amoebiasis, an important neglected tropical disease with a significant global health impact. The pathogenicity and survival of E. histolytica and its reptilian equivalent, Entamoeba invadens, relies on its ability to exhibit efficient motility, evade host immune responses, and exploit host resources, all of which are governed by the actin cytoskeleton remodeling. Our study demonstrates the early origin and the regulatory role of TALE homeobox protein EiHbox1 in actin-related cellular processes. Several genes involved in different biological pathways, including actin dynamics are differentially expressed in EiHbox1 silenced cells. EiHbox1 silenced parasites showed disrupted F-actin organization and loss of cellular polarity. EiHbox1's presence in the anterior region of migrating cells further suggests its involvement in maintaining cellular polarity. Loss of polarized morphology of EiHbox1 silenced parasites leads to altered motility from fast, directionally persistent, and highly chemotactic to slow, random, and less chemotactic, which subsequently leads to defective aggregation during encystation. EiHbox1 knockdown also resulted in a significant reduction in phagocytic capacity and poor capping response. These findings highlight the importance of EiHbox1 of E. invadens in governing cellular processes crucial for their survival, pathogenicity, and evasion of the host immune system.
Collapse
Affiliation(s)
- Meenakshi Pandey
- Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India
| | - Shilpa Sarkar
- Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India
| | - Sudip K Ghosh
- Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India
| |
Collapse
|
2
|
Bosch DE, Jeck WR, Siderovski DP. Self-activating G protein α subunits engage seven-transmembrane Regulator of G protein Signaling (RGS) proteins and a Rho guanine nucleotide exchange factor effector in the amoeba Naegleria fowleri. J Biol Chem 2022; 298:102167. [PMID: 35738399 PMCID: PMC9283941 DOI: 10.1016/j.jbc.2022.102167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 06/15/2022] [Accepted: 06/16/2022] [Indexed: 11/17/2022] Open
Abstract
The free-living amoeba Naegleria fowleri is a causative agent of primary amoebic meningoencephalitis and is highly resistant to current therapies, resulting in mortality rates >97%. As many therapeutics target G protein-centered signal transduction pathways, further understanding the functional significance of G protein signaling within N. fowleri should aid future drug discovery against this pathogen. Here, we report that the N. fowleri genome encodes numerous transcribed G protein signaling components, including G protein-coupled receptors (GPCRs), heterotrimeric G protein subunits, Regulator of G protein Signaling (RGS) proteins, and candidate Gα effector proteins. We found N. fowleri Gα subunits have diverse nucleotide cycling kinetics; Nf Gα5 and Gα7 exhibit more rapid nucleotide exchange than GTP hydrolysis (i.e. "self-activating" behavior). A crystal structure of Nf Gα7 highlights the stability of its nucleotide-free state, consistent with its rapid nucleotide exchange. Variations in the phosphate binding loop (P-loop) also contribute to nucleotide cycling differences among Gα subunits. Similar to plant G protein signaling pathways, N. fowleri Gα subunits selectively engage members of a large seven-transmembrane RGS protein family, resulting in acceleration of GTP hydrolysis. We show Nf Gα2 and Gα3 directly interact with a candidate Gα effector protein, RGS-RhoGEF, similar to mammalian Gα12/13 signaling pathways. We demonstrate Nf Gα2 and Gα3 each engage RGS-RhoGEF through a canonical Gα/RGS domain interface, suggesting a shared evolutionary origin with G protein signaling in the enteric pathogen Entamoeba histolytica. These findings further illuminate the evolution of G protein signaling and identify potential targets of pharmacological manipulation in Naegleria fowleri.
Collapse
Affiliation(s)
- Dustin E Bosch
- Department of Pathology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
| | - William R Jeck
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina, USA
| | - David P Siderovski
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, USA
| |
Collapse
|
3
|
Bharadwaj R, Kushwaha T, Ahmad A, Inampudi KK, Nozaki T. An atypical EhGEF regulates phagocytosis in Entamoeba histolytica through EhRho1. PLoS Pathog 2021; 17:e1010030. [PMID: 34807955 PMCID: PMC8648123 DOI: 10.1371/journal.ppat.1010030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 12/06/2021] [Accepted: 10/13/2021] [Indexed: 01/09/2023] Open
Abstract
The parasite Entamoeba histolytica is the etiological agent of amoebiasis, a major cause of morbidity and mortality due to parasitic diseases in developing countries. Phagocytosis is an essential mode of obtaining nutrition and has been associated with the virulence behaviour of E. histolytica. Signalling pathways involved in activation of cytoskeletal dynamics required for phagocytosis remains to be elucidated in this parasite. Our group has been studying initiation of phagocytosis and formation of phagosomes in E. histolytica and have described some of the molecules that play key roles in the process. Here we showed the involvement of non-Dbl Rho Guanine Nucleotide Exchange Factor, EhGEF in regulation of amoebic phagocytosis by regulating activation of EhRho1. EhGEF was found in the phagocytic cups during the progression of cups, until closure of phagosomes, but not in the phagosomes themselves. Our observation from imaging, pull down experiments and down regulating expression of different molecules suggest that EhGEF interacts with EhRho1 and it is required during initiation of phagocytosis and phagosome formation. Also, biophysical, and computational analysis reveals that EhGEF mediates GTP exchange on EhRho1 via an unconventional pathway. In conclusion, we describe a non-Dbl EhGEF of EhRho1 which is involved in endocytic processes of E. histolytica.
Collapse
Affiliation(s)
- Ravi Bharadwaj
- Division of Infectious Diseases, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Tushar Kushwaha
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Azhar Ahmad
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi, India
| | - Krishna K. Inampudi
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- * E-mail: (TN); , (S)
| |
Collapse
|
4
|
Villegas-Gómez I, Silva-Olivares A, Robles-Zepeda RE, Gálvez-Ruiz JC, Shibayama M, Valenzuela O. The Dichloromethane Fraction of Croton sonorae, A Plant Used in Sonoran Traditional Medicine, Affect Entamoeba histolytica Erythrophagocytosis and Gene Expression. Front Cell Infect Microbiol 2021; 11:693449. [PMID: 34368014 PMCID: PMC8343225 DOI: 10.3389/fcimb.2021.693449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 07/02/2021] [Indexed: 11/13/2022] Open
Abstract
Intestinal parasites are a global problem, mainly in developing countries. Obtaining information about plants and compounds that can combat gastrointestinal disorders and gastrointestinal symptoms is a fundamental first step in designing new treatment strategies. In this study, we analyzed the antiamoebic activity of the aerial part of Croton sonorae. The dichloromethane fraction of C. sonorae (CsDCMfx) contained flavonoids, terpenes, alkaloids, and glycosides. The ultrastructural morphology of the amoebae treated for 72 h with CsDCMfx was completely abnormal. CsDCMfx reduced erythrophagocytosis of trophozoites and the expression of genes involved in erythrocyte adhesion (gal/galnac lectin) and actin cytoskeleton rearrangement in the phagocytosis pathway (rho1 gtpase and formin1). Interestingly, CsDCMfx decreased the expression of genes involved in Entamoeba histolytica trophozoite pathogenesis, such as cysteine proteases (cp1, cp4, and cp5), sod, pfor, and enolase. These results showed that C. sonorae is a potential source of antiamoebic compounds.
Collapse
Affiliation(s)
- Isaac Villegas-Gómez
- Departamento de Ciencias Químico Biológicas, Universidad de Sonora, Hermosillo, México
| | - Angélica Silva-Olivares
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Ciudad de México, México
| | | | | | - Mineko Shibayama
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Ciudad de México, México
| | - Olivia Valenzuela
- Departamento de Ciencias Químico Biológicas, Universidad de Sonora, Hermosillo, México
| |
Collapse
|
5
|
Bharadwaj R, Bhattacharya A, Somlata. Coordinated activity of amoebic formin and profilin are essential for phagocytosis. Mol Microbiol 2021; 116:974-995. [PMID: 34278607 DOI: 10.1111/mmi.14787] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 10/24/2022]
Abstract
For the protist parasite Entamoeba histolytica, endocytic processes, such as phagocytosis, are essential for its survival in the human gut. The actin cytoskeleton is involved in the formation of pseudopods and phagosomal vesicles by incorporating a number of actin-binding and modulating proteins along with actin in a temporal manner. The actin dynamics, which comprises polymerization, branching, and depolymerization is very tightly regulated and takes place directionally at the sites of initiation of phagocytosis. Formin and profilin are two actin-binding proteins that are known to regulate actin cytoskeleton dynamics and thereby, endocytic processes. In this article, we report the participation of formin and profilin in E. histolytica phagocytosis and propose that these two proteins interact with each other and their sequential recruitment at the site is required for the successful completion of phagocytosis. The evidence is based on detailed microscopic, live imaging, interaction studies, and expression downregulation. The cells downregulated for expression of formin show absence of profilin at the site of phagocytosis, whereas downregulation of profilin does not affect formin localization.
Collapse
Affiliation(s)
- Ravi Bharadwaj
- Department of Medicine, UMass Medical School, Worcester, MA, USA
| | | | - Somlata
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi, India
| |
Collapse
|
6
|
Filić V, Mijanović L, Putar D, Talajić A, Ćetković H, Weber I. Regulation of the Actin Cytoskeleton via Rho GTPase Signalling in Dictyostelium and Mammalian Cells: A Parallel Slalom. Cells 2021; 10:1592. [PMID: 34202767 PMCID: PMC8305917 DOI: 10.3390/cells10071592] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/16/2021] [Accepted: 06/16/2021] [Indexed: 01/15/2023] Open
Abstract
Both Dictyostelium amoebae and mammalian cells are endowed with an elaborate actin cytoskeleton that enables them to perform a multitude of tasks essential for survival. Although these organisms diverged more than a billion years ago, their cells share the capability of chemotactic migration, large-scale endocytosis, binary division effected by actomyosin contraction, and various types of adhesions to other cells and to the extracellular environment. The composition and dynamics of the transient actin-based structures that are engaged in these processes are also astonishingly similar in these evolutionary distant organisms. The question arises whether this remarkable resemblance in the cellular motility hardware is accompanied by a similar correspondence in matching software, the signalling networks that govern the assembly of the actin cytoskeleton. Small GTPases from the Rho family play pivotal roles in the control of the actin cytoskeleton dynamics. Indicatively, Dictyostelium matches mammals in the number of these proteins. We give an overview of the Rho signalling pathways that regulate the actin dynamics in Dictyostelium and compare them with similar signalling networks in mammals. We also provide a phylogeny of Rho GTPases in Amoebozoa, which shows a variability of the Rho inventories across different clades found also in Metazoa.
Collapse
Affiliation(s)
- Vedrana Filić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
| | | | | | | | | | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
| |
Collapse
|
7
|
Bharadwaj R, Sharma S, Arya R, Bhattacharya S, Bhattacharya A. EhRho1 regulates phagocytosis by modulating actin dynamics through EhFormin1 and EhProfilin1 inEntamoeba histolytica. Cell Microbiol 2018; 20:e12851. [DOI: 10.1111/cmi.12851] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 03/12/2018] [Accepted: 03/25/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Ravi Bharadwaj
- School of Life Sciences; Jawaharlal Nehru University; New Delhi India
| | - Shalini Sharma
- School of Life Sciences; Jawaharlal Nehru University; New Delhi India
| | - Ranjana Arya
- School of Biotechnology; Jawaharlal Nehru University; New Delhi India
| | - Sudha Bhattacharya
- School of Environmental Sciences; Jawaharlal Nehru University; New Delhi India
| | - Alok Bhattacharya
- School of Life Sciences; Jawaharlal Nehru University; New Delhi India
| | | |
Collapse
|
8
|
Neuwald AF, Aravind L, Altschul SF. Inferring joint sequence-structural determinants of protein functional specificity. eLife 2018; 7. [PMID: 29336305 PMCID: PMC5770160 DOI: 10.7554/elife.29880] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 12/22/2017] [Indexed: 01/05/2023] Open
Abstract
Residues responsible for allostery, cooperativity, and other subtle but functionally important interactions remain difficult to detect. To aid such detection, we employ statistical inference based on the assumption that residues distinguishing a protein subgroup from evolutionarily divergent subgroups often constitute an interacting functional network. We identify such networks with the aid of two measures of statistical significance. One measure aids identification of divergent subgroups based on distinguishing residue patterns. For each subgroup, a second measure identifies structural interactions involving pattern residues. Such interactions are derived either from atomic coordinates or from Direct Coupling Analysis scores, used as surrogates for structural distances. Applying this approach to N-acetyltransferases, P-loop GTPases, RNA helicases, synaptojanin-superfamily phosphatases and nucleases, and thymine/uracil DNA glycosylases yielded results congruent with biochemical understanding of these proteins, and also revealed striking sequence-structural features overlooked by other methods. These and similar analyses can aid the design of drugs targeting allosteric sites.
Collapse
Affiliation(s)
- Andrew F Neuwald
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, United States.,Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, United States
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - Stephen F Altschul
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| |
Collapse
|
9
|
Bharadwaj R, Arya R, Shahid mansuri M, Bhattacharya S, Bhattacharya A. EhRho1 regulates plasma membrane blebbing through PI3 kinase inEntamoeba histolytica. Cell Microbiol 2017; 19. [DOI: 10.1111/cmi.12751] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/03/2017] [Accepted: 04/16/2017] [Indexed: 02/06/2023]
Affiliation(s)
- Ravi Bharadwaj
- School of Biotechnology; Jawaharlal Nehru University; New Delhi India
| | - Ranjana Arya
- School of Biotechnology; Jawaharlal Nehru University; New Delhi India
| | | | - Sudha Bhattacharya
- School of environmental Sciences; Jawaharlal Nehru University; New Delhi India
| | - Alok Bhattacharya
- School of Life Sciences; Jawaharlal Nehru University; New Delhi India
| |
Collapse
|
10
|
Hernandez-Flores A, Almaraz-Barrera MDJ, Lozano-Amado D, Correa-Basurto J, Rojo-Dominguez A, Luna-Rivera E, Schnoor M, Guillen N, Hernandez-Rivas R, Vargas M. A new nucleocytoplasmic RhoGAP protein contributes to control the pathogenicity ofEntamoeba histolyticaby regulating EhRacC and EhRacD activity. Cell Microbiol 2016; 18:1653-1672. [DOI: 10.1111/cmi.12603] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 03/29/2016] [Accepted: 04/18/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Araceli Hernandez-Flores
- Department of Molecular Biomedicine; Center of Research and Advanced Studies of the I.P.N; Mexico City, D.F. Mexico
| | - Ma de Jesus Almaraz-Barrera
- Department of Molecular Biomedicine; Center of Research and Advanced Studies of the I.P.N; Mexico City, D.F. Mexico
| | - Daniela Lozano-Amado
- Department of Molecular Biomedicine; Center of Research and Advanced Studies of the I.P.N; Mexico City, D.F. Mexico
| | - Jose Correa-Basurto
- High School of Medicine of the I.P.N; Molecular Modeling Laboratory and Drug Design; Mexico City, D.F. Mexico
| | - Arturo Rojo-Dominguez
- Cuajimalpa Unit., Department of Natural Sciences; Metropolitan Autonomous University; Mexico City, D.F. Mexico
| | - Eva Luna-Rivera
- Department of Molecular Biomedicine; Center of Research and Advanced Studies of the I.P.N; Mexico City, D.F. Mexico
| | - Michael Schnoor
- Department of Molecular Biomedicine; Center of Research and Advanced Studies of the I.P.N; Mexico City, D.F. Mexico
| | - Nancy Guillen
- Institut Pasteur; Department of Cell Biology and Infection; Paris France
| | - Rosaura Hernandez-Rivas
- Department of Molecular Biomedicine; Center of Research and Advanced Studies of the I.P.N; Mexico City, D.F. Mexico
| | - Miguel Vargas
- Department of Molecular Biomedicine; Center of Research and Advanced Studies of the I.P.N; Mexico City, D.F. Mexico
| |
Collapse
|
11
|
Bosch D, Siderovski DP. Entamoeba histolytica RacC selectively engages p21-activated kinase effectors. Biochemistry 2015; 54:404-12. [PMID: 25529118 PMCID: PMC4303316 DOI: 10.1021/bi501226f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Rho family GTPases modulate actin cytoskeleton dynamics by signaling through multiple effectors, including the p21-activated kinases (PAKs). The intestinal parasite Entamoeba histolytica expresses ∼20 Rho family GTPases and seven isoforms of PAK, two of which have been implicated in pathogenesis-related processes such as amoebic motility and invasion and host cell phagocytosis. Here, we describe two previously unstudied PAK isoforms, EhPAK4 and EhPAK5, as highly specific effectors of EhRacC. A structural model based on 2.35 Å X-ray crystallographic data of a complex between EhRacC(Q65L)·GTP and the EhPAK4 p21 binding domain (PBD) reveals a fairly well-conserved Rho/effector interface despite deviation of the PBD α-helix. A structural comparison with EhRho1 in complex with EhFormin1 suggests likely determinants of Rho family GTPase signaling specificity in E. histolytica. These findings suggest a high degree of Rho family GTPase diversity and specificity in the single-cell parasite E. histolytica. Because PAKs regulate pathogenesis-related processes in E. histolytica, they may be valid pharmacologic targets for anti-amoebiasis drugs.
Collapse
Affiliation(s)
- Dustin
E. Bosch
- Department
of Pharmacology, The University of North
Carolina, Chapel Hill, North Carolina 27514, United States
| | - David P. Siderovski
- Department
of Physiology & Pharmacology, West Virginia
University School of Medicine, Robert C. Byrd Health Sciences Center, Morgantown, West Virginia 26506, United States,Address: 3051A Health Sciences
North, P.O. Box 9229, West Virginia University School of Medicine,
Morgantown, WV 26506-9229. E-mail: . Telephone: (304) 293-4991
| |
Collapse
|
12
|
Abstract
The parasite Entamoeba histolytica causes amebic colitis and systemic amebiasis. Among the known amebic factors contributing to pathogenesis are signaling pathways involving heterotrimeric and Ras superfamily G proteins. Here, we review the current knowledge of the roles of heterotrimeric G protein subunits, Ras, Rho and Rab GTPase families in E. histolytica pathogenesis, as well as of their downstream signaling effectors and nucleotide cycle regulators. Heterotrimeric G protein signaling likely modulates amebic motility and attachment to and killing of host cells, in part through activation of an RGS-RhoGEF (regulator of G protein signaling-Rho guanine nucleotide exchange factor) effector. Rho family GTPases, as well as RhoGEFs and Rho effectors (formins and p21-activated kinases) regulate the dynamic actin cytoskeleton of E. histolytica and associated pathogenesis-related cellular processes, such as migration, invasion, phagocytosis and evasion of the host immune response by surface receptor capping. A remarkably large family of 91 Rab GTPases has multiple roles in a complex amebic vesicular trafficking system required for phagocytosis and pinocytosis and secretion of known virulence factors, such as amebapores and cysteine proteases. Although much remains to be discovered, recent studies of G protein signaling in E. histolytica have enhanced our understanding of parasitic pathogenesis and have also highlighted possible targets for pharmacological manipulation.
Collapse
|
13
|
Bosch DE, Kimple AJ, Manning AJ, Muller RE, Willard FS, Machius M, Rogers SL, Siderovski DP. Structural determinants of RGS-RhoGEF signaling critical to Entamoeba histolytica pathogenesis. Structure 2012; 21:65-75. [PMID: 23260656 DOI: 10.1016/j.str.2012.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Revised: 11/20/2012] [Accepted: 11/20/2012] [Indexed: 10/27/2022]
Abstract
G protein signaling pathways, as key components of physiologic responsiveness and timing, are frequent targets for pharmacologic intervention. Here, we identify an effector for heterotrimeric G protein α subunit (EhGα1) signaling from Entamoeba histolytica, the causative agent of amoebic colitis. EhGα1 interacts with this effector and guanosine triphosphatase-accelerating protein, EhRGS-RhoGEF, in a nucleotide state-selective fashion. Coexpression of EhRGS-RhoGEF with constitutively active EhGα1 and EhRacC leads to Rac-dependent spreading in Drosophila S2 cells. EhRGS-RhoGEF overexpression in E. histolytica trophozoites leads to reduced migration toward serum and lower cysteine protease activity, as well as reduced attachment to, and killing of, host cells. A 2.3 Å crystal structure of the full-length EhRGS-RhoGEF reveals a putative inhibitory helix engaging the Dbl homology domain Rho-binding surface and the pleckstrin homology domain. Mutational analysis of the EhGα1/EhRGS-RhoGEF interface confirms a canonical "regulator of G protein signaling" domain rather than a RhoGEF-RGS ("rgRGS") domain, suggesting a convergent evolution toward heterotrimeric and small G protein cross-talk.
Collapse
Affiliation(s)
- Dustin E Bosch
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Adam J Kimple
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Alyssa J Manning
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Robin E Muller
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Francis S Willard
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Mischa Machius
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Stephen L Rogers
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - David P Siderovski
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Robert C. Byrd Health Sciences Center, Morgantown, WV 26506, USA.
| |
Collapse
|
14
|
Bosch DE, Siderovski DP. Structural determinants of ubiquitin conjugation in Entamoeba histolytica. J Biol Chem 2012; 288:2290-302. [PMID: 23209297 DOI: 10.1074/jbc.m112.417337] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ubiquitination is important for numerous cellular processes in most eukaryotic organisms, including cellular proliferation, development, and protein turnover by the proteasome. The intestinal parasite Entamoeba histolytica harbors an extensive ubiquitin-proteasome system. Proteasome inhibitors are known to impair parasite proliferation and encystation, suggesting the ubiquitin-proteasome pathway as a viable therapeutic target. However, no functional studies of the E. histolytica ubiquitination enzymes have yet emerged. Here, we have cloned and characterized multiple E. histolytica ubiquitination components, spanning ubiquitin and its activating (E1), conjugating (E2), and ligating (E3) enzymes. Crystal structures of EhUbiquitin reveal a clustering of unique residues on the α1 helix surface, including an eighth surface lysine not found in other organisms, which may allow for a unique polyubiquitin linkage in E. histolytica. EhUbiquitin is activated by and forms a thioester bond with EhUba1 (E1) in vitro, in an ATP- and magnesium-dependent fashion. EhUba1 exhibits a greater maximal initial velocity of pyrophosphate:ATP exchange than its human homolog, suggesting different kinetics of ubiquitin activation in E. histolytica. EhUba1 engages the E2 enzyme EhUbc5 through its ubiquitin-fold domain to transfer the EhUbiquitin thioester. However, EhUbc5 has a >10-fold preference for EhUba1∼Ub compared with unconjugated EhUba1. A crystal structure of EhUbc5 allowed prediction of a noncovalent "backside" interaction with EhUbiquitin and E3 enzymes. EhUbc5 selectively engages EhRING1 (E3) to the exclusion of two HECT family E3 ligases, and mutagenesis indicates a conserved mode of E2/RING-E3 interaction in E. histolytica.
Collapse
Affiliation(s)
- Dustin E Bosch
- Department of Pharmacology, The University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | | |
Collapse
|
15
|
Bosch DE, Yang B, Siderovski DP. Entamoeba histolytica Rho1 regulates actin polymerization through a divergent, diaphanous-related formin. Biochemistry 2012; 51:8791-801. [PMID: 23050667 PMCID: PMC3491106 DOI: 10.1021/bi300954g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Entamoeba histolytica requires a dynamic actin cytoskeleton for intestinal and systemic pathogenicity. Diaphanous-related formins represent an important family of actin regulators that are activated by Rho GTPases. The E. histolytica genome encodes a large family of Rho GTPases and three diaphanous-related formins, of which EhFormin1 is known to regulate mitosis and cytokinesis in trophozoites. We demonstrate that EhFormin1 modulates actin polymerization through its formin homology 2 domain. Despite a highly divergent diaphanous autoinhibitory domain, EhFormin1 is autoinhibited by an N- and C-terminal intramolecular interaction but activated upon binding of EhRho1 to the N-terminal domain tandem. A crystal structure of the EhRho1·GTPγS-EhFormin1 complex illustrates an EhFormin1 conformation that diverges from mammalian mDia1 and lacks a secondary interaction with a Rho insert helix. The structural model also highlights residues required for specific recognition of the EhRho1 GTPase and suggests that the molecular mechanisms of EhFormin1 autoinhibition and activation differ from those of mammalian homologues.
Collapse
Affiliation(s)
- Dustin E. Bosch
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7365 USA
| | - Bing Yang
- Department of Cell and Developmental Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7365 USA
| | - David P. Siderovski
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, WV 26506-9229 USA,Address correspondence to Dr. David P. Siderovski, 3051 Robert C. Byrd Health Sciences Center, West Virginia University School of Medicine, Morgantown, WV 26506-9229 USA. Tel: 304-293-4991;
| |
Collapse
|