Yersinia Virulence Factor YopM Induces Sustained RSK Activation by Interfering with Dephosphorylation

Abstract

BackgroundPathogenic yersiniae inject several effector proteins (Yops) into host cells, which subverts immune functions and enables the bacteria to survive within the host organism. YopM, whose deletion in enteropathogenic yersiniae results in a dramatic loss of virulence, has previously been shown to form a complex with and activate the multifunctional kinases PKN2 and RSK1 in transfected cells.Methodology/Principal FindingsIn a near physiological approach with double-affinity-tagged YopM being translocated into the macrophage cell line J774A.1 via the natural type three secretion system of Yersinia we verified the interaction of YopM with PKN2 and RSK1 and detected association with additional PKN and RSK isoforms. In transfected and infected cells YopM induced sustained phosphorylation of RSK at its activation sites serine-380 and serine-221 even in the absence of signalling from its upstream kinase ERK1/2, suggesting inhibition of dephosphorylation. ATP-depletion and in vitro assays using purified components directly confirmed that YopM shields RSK isoforms from phosphatase activity towards serines 380 and 221.Conclusions/SignificanceOur study suggests that during Yersinia infection YopM induces sustained activation of RSK by blocking dephosphorylation of its activatory phosphorylation sites. This may represent a novel mode of action of a bacterial virulence factor.

Uncovering an Important Role for YopJ in the Inhibition of Caspase-1 in Activated Macrophages and Promoting Yersinia pseudotuberculosis Virulence

“…The YopM C-terminal tail is required for Yersinia virulence (51,52) and inhibition of caspase-1 activation (31). Binding of YopM to RSK1 induces activation of its kinase activity (50,53). Activation of RSK1 occurs independently of the upstream kinases ERK1/2 and is sustained because dephosphorylation of RSK1 is prevented in the presence of YopM (50,53).…”

“…Binding of YopM to RSK1 induces activation of its kinase activity (50,53). Activation of RSK1 occurs independently of the upstream kinases ERK1/2 and is sustained because dephosphorylation of RSK1 is prevented in the presence of YopM (50,53). Binding of RSK1 to YopM in Y. pseudotuberculosis-infected macrophages also stimulates the formation of high-molecularweight complexes of RSK1 and YopM (51).…”

Structure of an SspH1-PKN1 Complex Reveals the Basis for Host Substrate Recognition and Mechanism of Activation for a Bacterial E3 Ubiquitin Ligase

“…PKN1 is a serine/ threonine kinase whose activity is regulated through interactions with Rho family GTPases (24)(25)(26)(27) or by proteolytic activation (28), both of which can trigger PKN1 activation during Salmonella infection (29)(30)(31). PKN1 is also a target of the bacterial effector YopM from Yersinia (32). PKN1 influences at least three aspects of host immune signaling.…”

Insight into Bacterial Virulence Mechanisms against Host Immune Response via the Yersinia pestis-Human Protein-Protein Interaction Network

“…Three human-pathogenic Yersinia species share a 70-kb plasmid that encodes the T3SS, by which the bacteria inject a set of virulent effectors called Yersinia outer membrane proteins (Yops) into the mammalian host cells (20). The molecular mechanisms of how these Yop effectors function during infection remain a focus of intensive research (33,51,81).…”