Mammalian Pragmin regulates Src family kinases via the Glu-Pro-Ile-Tyr-Ala (EPIYA) motif that is exploited by bacterial effectors

Abstract

Several pathogenic bacteria have adopted effector proteins that, upon delivery into mammalian cells, undergo tyrosine phosphorylation at the Glu-Pro-Ile-Tyr-Ala (EPIYA) or EPIYA-like sequence motif by host kinases such as Src family kinases (SFKs). This EPIYA phosphorylation triggers complex formation of bacterial effectors with SH2 domain-containing proteins that results in perturbation of host cell signaling and subsequent pathogenesis. Although the presence of such an anomalous protein interaction suggests the existence of a mammalian EPIYA-containing protein whose function is mimicked or subverted by bacterial EPIYA effectors, no molecule that uses the EPIYA motif for biological function has so far been reported in mammals. Here we show that mammalian Pragmin/SgK223 undergoes tyrosine phosphorylation at the EPIYA motif by SFKs and thereby acquires the ability to interact with the SH2 domain of the C-terminal Src kinase (Csk), a negative regulator of SFKs. The Pragmin-Csk interaction prevents translocalization of Csk from the cytoplasm to the membrane and subsequent inactivation of membrane-associated SFKs. As a result, SFK activity is sustained in cells where Pragmin is phosphorylated at the EPIYA motif. Because EPIYA phosphorylation of Pragmin is mediated by SFKs, cytoplasmic sequestration of Csk by Pragmin establishes a positive feedback regulation of SFK activation. Remarkably, the Helicobacter pylori EPIYA effector CagA binds to the Csk SH2 domain in place of Pragmin and enforces membrane recruitment of Csk and subsequent inhibition of SFKs. This work identifies Pragmin as a mammalian EPIYA effector and suggests that bacterial EPIYA effectors target Pragmin to subvert SFKs for successful infection. mammalian proteomes | bacterial virulence factors

NACK Is an Integral Component of the Notch Transcriptional Activation Complex and Is Critical for Development and Tumorigenesis

“…Herein we report the identification of a novel binding partner of the Notch transcriptional activation complex, which we termed NACK. This protein has been previously identified as Pragmin and has been shown to interact with Rho family GTPases (27) and C-terminal Src kinase (28). Using both in vivo and in vitro approaches we demonstrated that NACK acts as a regulator of Notch transcription, is necessary for Notch-driven tumorigenesis, and is required for embryonic development.…”

Evaluation of Cell- Morphological Changes by Helicobacter pylori CagA and Pragmin in AGS Human Gastric Carcinoma Cells

“…Consistent with our results, Safari et al reported that in the presence of CagA H. pylori, the amount of CSK /Pragmin interaction was reduced. In fact, they found the competition between CagA and Pragmin to interact with CSK in tyrosine phosphorylation manner at EPIYA motif (19). Of note, it was demonstrated that CagA/CSK interaction occurs at plasma membrane, whereas Pragmin interact with CSK at cytoplasm, and thereby the possible mechanisms that are involved in related downstream molecules to induce elongated cells may also be different.…”

“…After tyrosine phosphorylation at EPIYA motif, Pragmin can interact with CSK. Interestingly, it was found that the cells with high expression of Pragmin have the elongated morphology that contributes to tumor invasion and metastasis (19)(20)(21). In this regard, it was shown that ectopic expression of Pragmin in human pancreatic duct epithelial (PDAC) cells induced an elongated mesenchymal-like cell morphology, which is associated with increased cell migration and invasion (22).…”

Convergent evolution and mimicry of protein linear motifs in host–pathogen interactions

“…Pathogen mimics are widely distributed across the tree of life, including proteobacteria, spirochaetes, firmicutes, fungi, chromalveolata, excavata and animalia [2 , [9][10][11]. Similar to viruses, these linear motif mimics have contributed to the discovery of new host linear motifs [12] and mediate a wide range of processes, such as adhesion to target cells, virulence protein secretion, perturbation of cell signaling, and inhibition of host defense systems [2 ,9]. Despite the growing recognition of their relevance, we are only beginning to understand the evolutionary patterns and comparative properties of host motifs and their pathogen mimics.…”