EhGEF2, a Dbl-RhoGEF from Entamoeba histolytica has atypical biochemical properties and participates in essential cellular processes

Rosa, Claudia H. González-De la; Arias-Romero, Luis E.; Almaráz-Barrera, Ma. de Jesús; Hernández‐Rivas, Rosaura; Sosa‐Peinado, Alejandro; Rojo‐Domínguez, Arturo; Robles-Flores, Martha; Vargas, Miguel

doi:10.1016/j.molbiopara.2006.10.007

Cited by 20 publications

(21 citation statements)

References 31 publications

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“…Consistent with this theme, EhRGS-RhoGEF requires co-expression, not only with constitutively active EhGα1, but also with constitutively active EhRacC, to achieve apparent activation as evidenced by S2 cell spreading. Little is currently known about EhRacC signaling in E. histolytica , although it is evidently a substrate for EhGEF2 in vitro (Gonzalez De la Rosa et al, 2007). EhRacC was seen to bind EhRGS-RhoGEF directly, exclusively in the GTP-bound conformation, suggesting that EhRGS-RhoGEF may serve as an EhRacC effector.…”

Section: Discussionmentioning

confidence: 99%

Structural Determinants of RGS-RhoGEF Signaling Critical to Entamoeba histolytica Pathogenesis

et al. 2013

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Summary 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 GTPase-accelerating protein (GAP), EhRGS-RhoGEF, in a nucleotide state-selective fashion. Co-expression 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 DH domain Rho-binding surface and the PH domain. Mutational analysis of the EhGα1/EhRGS-RhoGEF interface confirms a canonical RGS domain rather than a RhoGEF-RGS (“rgRGS”) domain, suggesting a convergent evolution toward heterotrimeric and small G-protein cross-talk.

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Section: Discussionmentioning

confidence: 99%

Structural Determinants of RGS-RhoGEF Signaling Critical to Entamoeba histolytica Pathogenesis

et al. 2013

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“…101 Both the N-terminal and DH domain regions were seen to contribute to EhGEF2 membrane localization. EhGEF2 was also suggested to activate EhRacA-D, EhRacG-H and EhCdc42 in vitro , 101 although no kinetic analysis was provided in this report and the fluorescence time courses shown appear to be caused by buffer shifts upon GEF addition rather than a single exponential binding event per se . Which Rho substrates and dominant-negative mutant-impaired signals are relevant for the observed in vivo effects are currently unknown.…”

Section: Ras Superfamily Gtpases In E Histolyticamentioning

confidence: 97%

G protein signaling in the parasite Entamoeba histolytica

Bosch

Siderovski

2013

Exp Mol Med

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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.

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“…These cytoskeleton functions are regulated by a panel of important proteins, including the small GTPases RacG [27] and RacA [28], their corresponding GTP exchange factors [29], [30], [31], the PAK kinases [32], [33] and the actin-filament cross-linker Filamin A (previously referred to as ABP120) [34]. Blocking myosin II inhibits surface receptor capping and, as a result, trophozoites are unable to invade living tissues [15].…”

Section: Introductionmentioning

confidence: 99%

A Proteomic and Cellular Analysis of Uropods in the Pathogen Entamoeba histolytica

et al. 2011

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Exposure of Entamoeba histolytica to specific ligands induces cell polarization via the activation of signalling pathways and cytoskeletal elements. The process leads to formation of a protruding pseudopod at the front of the cell and a retracting uropod at the rear. In the present study, we show that the uropod forms during the exposure of trophozoites to serum isolated from humans suffering of amoebiasis. To investigate uropod assembly, we used LC-MS/MS technology to identify protein components in isolated uropod fractions. The galactose/N-acetylgalactosamine lectin, the immunodominant antigen M17 (which is specifically recognized by serum from amoeba-infected persons) and a few other cells adhesion-related molecules were primarily involved. Actin-rich cytoskeleton components, GTPases from the Rac and Rab families, filamin, α-actinin and a newly identified ezrin-moesin-radixin protein were the main factors found to potentially interact with capped receptors. A set of specific cysteine proteases and a serine protease were enriched in isolated uropod fractions. However, biological assays indicated that cysteine proteases are not involved in uropod formation in E. histolytica, a fact in contrast to the situation in human motile immune cells. The surface proteins identified here are testable biomarkers which may be either recognized by the immune system and/or released into the circulation during amoebiasis.

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EhGEF2, a Dbl-RhoGEF from Entamoeba histolytica has atypical biochemical properties and participates in essential cellular processes

Cited by 20 publications

References 31 publications

Structural Determinants of RGS-RhoGEF Signaling Critical to Entamoeba histolytica Pathogenesis

Structural Determinants of RGS-RhoGEF Signaling Critical to Entamoeba histolytica Pathogenesis

G protein signaling in the parasite Entamoeba histolytica

A Proteomic and Cellular Analysis of Uropods in the Pathogen Entamoeba histolytica

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