The Toxoplasma Pseudokinase ROP5 Is an Allosteric Inhibitor of the Immunity-related GTPases

Reese, Michael L.; Shah, Niket; Boothroyd, John C.

doi:10.1074/jbc.m114.567057

Cited by 69 publications

(81 citation statements)

References 53 publications

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“…The interaction between Irga6 and ROP5 has been crystallized from purified components (Reese et al, 2014) and does not require post-translational modification of either protein. Yet, both phosphorylation and glycosylation have been reported for members of the ROP5/ROP18/ GRA7 complex (Dunn et al, 2008;Luo et al, 2011;Treeck et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

TheToxoplasma gondiirhoptry protein ROP18 is an Irga6‐specific kinase and regulated by the dense granule protein GRA7

Hermanns

Müller

Könen‐Waisman

et al. 2015

Cellular Microbiology

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SummaryIn mice, avirulent strains (e.g. types II and III) of the protozoan parasite Toxoplasma gondii are restricted by the immunity‐related GTPase (IRG) resistance system. Loading of IRG proteins onto the parasitophorous vacuolar membrane (PVM) is required for vacuolar rupture resulting in parasite clearance. In virulent strain (e.g. type I) infections, polymorphic effector proteins ROP5 and ROP18 cooperate to phosphorylate and thereby inactivate mouse IRG proteins to preserve PVM integrity. In this study, we confirmed the dense granule protein GRA7 as an additional component of the ROP5/ROP18 kinase complex and identified GRA7 association with the PVM by direct binding to ROP5. The absence of GRA7 results in reduced phosphorylation of Irga6 correlated with increased vacuolar IRG protein amounts and attenuated virulence. Earlier work identified additional IRG proteins as targets of T. gondii ROP18 kinase. We show that the only specific target of ROP18 among IRG proteins is in fact Irga6. Similarly, we demonstrate that GRA7 is strictly an Irga6‐specific virulence effector. This identifies T. gondii GRA7 as a regulator for ROP18‐specific inactivation of Irga6. The structural diversity of the IRG proteins implies that certain family members constitute additional specific targets for other yet unknown T. gondii virulence effectors.

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Section: Discussionmentioning

confidence: 99%

TheToxoplasma gondiirhoptry protein ROP18 is an Irga6‐specific kinase and regulated by the dense granule protein GRA7

Hermanns

Müller

Könen‐Waisman

et al. 2015

Cellular Microbiology

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“…Additionally, ROP5 binds directly to monomeric IRGs, preventing their oligomerization in vitro (36,82). The binding of ROP5 to IRGs alters the conformation of SW1, preventing oligomerization (97) and favoring phosphorylation by ROP18 (36) (Figure 4). The interfaces of ROP5 and IRGs that interact show evidence of strong selective pressure, suggesting they have coevolved as virulence and defense effectors in a gene-for-gene manner (7,36,97).…”

Section: Targeting Of Host Innate Immunitymentioning

confidence: 98%

“…The binding of ROP5 to IRGs alters the conformation of SW1, preventing oligomerization (97) and favoring phosphorylation by ROP18 (36) (Figure 4). The interfaces of ROP5 and IRGs that interact show evidence of strong selective pressure, suggesting they have coevolved as virulence and defense effectors in a gene-for-gene manner (7,36,97). Consistent with this model, the heightened resistance of a wild-derived house mouse (Mus musculus) has been associated with expression of a novel IRG haplotype that appears to block the ability of ROP5 to recognize Irga6 (70).…”

Section: Targeting Of Host Innate Immunitymentioning

confidence: 98%

Genetic Mapping of Pathogenesis Determinants inToxoplasma gondii

Behnke

Dubey

Sibley

2016

Annu. Rev. Microbiol.

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Toxoplasma gondii is a widespread parasite of warm-blooded vertebrates that also causes opportunistic infections in humans. Rodents are a natural host for asexually replicating forms, whereas cats serve as the definitive host for sexual development. The laboratory mouse provides a model to study pathogenesis. Strains of T. gondii are globally diverse, with more than 16 distinct haplogroups clustered into 6 major clades. Forward genetic analysis of genetic crosses between different lineages has been used to define the molecular basis of acute virulence in the mouse. These studies have identified a family of secretory serine/threonine rhoptry kinases that target innate immune pathways to protect intracellular parasites from destruction. Rhoptry kinases target immunity-related GTPases, a family of immune effectors that is expanded in rodents. Similar forward genetic studies may be useful to define the basis of pathogenesis in other hosts, including humans, where infections of different strains present with variable clinical severity.

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“…ROP5B stabilizes the inactive form of IRGa6 by interacting with it through the C-lobe of the kinase domain (Figure 4G) (Fleckenstein et al, 2012; Reese et al, 2014). The conformation of the pseudokinase domain in the ROP5B/IRGa6 structure is nearly identical to that observed in structures of apo ROP5B and ATP-bound ROP5B, suggesting that the pseudokinase domain does not need to undergo significant conformational changes in order to engage with IRGa6 (Reese and Boothroyd, 2011; Reese et al, 2014). It is therefore likely that interaction of ROP5B with IRGa6 is regulated through a different mechanism.…”

Section: “Repurposing” the Kinase Domain For Non-catalytic Functionsmentioning

confidence: 99%

Structural Basis for the Non-catalytic Functions of Protein Kinases

2016

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Summary Protein kinases are known primarily for their ability to phosphorylate protein substrates, which constitutes an essential biological process. Recently, compelling evidence has accumulated that the functions of many protein kinases extend beyond phosphorylation and include an impressive spectrum of non-catalytic roles, such as scaffolding, allosteric regulation, or even protein-DNA interactions. How the conserved kinase fold shared by all metazoan protein kinases can accomplish these diverse tasks in a specific and regulated manner is poorly understood. In this review, we analyze the molecular mechanisms supporting phosphorylation-independent signaling by kinases and attempt to identify common and unique structural characteristics that enable kinases to perform non-catalytic functions. We also discuss how post-translational modifications, protein-protein interactions, and small molecules modulate these non-canonical kinase functions. Finally, we highlight current efforts in the targeted design of small molecule modulators of non-catalytic kinase functions – a new pharmacological challenge for which structural considerations are more important than ever.

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The Toxoplasma Pseudokinase ROP5 Is an Allosteric Inhibitor of the Immunity-related GTPases

Cited by 69 publications

References 53 publications

TheToxoplasma gondiirhoptry protein ROP18 is an Irga6‐specific kinase and regulated by the dense granule protein GRA7

TheToxoplasma gondiirhoptry protein ROP18 is an Irga6‐specific kinase and regulated by the dense granule protein GRA7

Genetic Mapping of Pathogenesis Determinants inToxoplasma gondii

Structural Basis for the Non-catalytic Functions of Protein Kinases

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