EPIYA Motif Is a Membrane-targeting Signal of Helicobacter pylori Virulence Factor CagA in Mammalian Cells

Abstract

Helicobacter pylori contributes to the development of peptic ulcers and atrophic gastritis. Furthermore, H. pylori strains carrying the cagA gene are more virulent than cagA-negative strains and are associated with the development of gastric adenocarcinoma. The cagA gene product, CagA, is translocated into gastric epithelial cells and localizes to the inner surface of the plasma membrane, in which it undergoes tyrosine phosphorylation at the Glu-Pro-Ile-Tyr-Ala (EPIYA) motif. Tyrosine-phosphorylated CagA specifically binds to and activates Src homology 2-containing protein-tyrosine phosphatase-2 (SHP-2) at the membrane, thereby inducing an elongated cell shape termed the hummingbird phenotype. Accordingly, membrane tethering of CagA is an essential prerequisite for the pathogenic activity of CagA. We show here that membrane association of CagA requires the EPIYA-containing region but is independent of EPIYA tyrosine phosphorylation. We further show that specific deletion of the EPIYA motif abolishes the ability of CagA to associate with the membrane. Conversely, reintroduction of an EPIYA sequence into a CagA mutant that lacks the EPIYA-containing region restores membrane association of CagA. Thus, the presence of a single EPIYA motif is necessary for the membrane localization of CagA. Our results indicate that the EPIYA motif has a dual function in membrane association and tyrosine phosphorylation, both of which are critically involved in the activity of CagA to deregulate intracellular signaling, and suggest that the EPIYA motif is a crucial therapeutic target of cagA-positive H. pylori infection.

Structural insights into Helicobacter pylori oncoprotein CagA interaction with β1 integrin

“…The structure of CagA presented here provides a clear definition of the domain organization of the large, stable N-terminal region of CagA, covering about two-thirds of the whole CagA protein. Some of these domains share different degrees of similarities with prokaryotic or eukaryotic proteins, the aim of which might be protein mimicry, which could explain how different domains of CagA can affect location of the protein in H. pylori as well as the eukaryotic target cell (26)(27)(28)(29). Another remarkable characteristic of CagA N-terminal region is its flexibility, in particular the domain D1 (residues 1-300).…”

Linking epithelial polarity and carcinogenesis by multitasking Helicobacter pylori virulence factor CagA

“…The tyrosine phosphorylation site of CagA is characterized by the Glu-Pro-IleTyr-Ala (EPIYA) motif, which is present in multiple numbers in the carboxy-terminal polymorphic region (EPIYA-repeat region) of the protein (Higashi et al, 2002a, b). On the basis of sequences flanking the EPIYA motifs, four distinct EPIYA segments, EPIYA-A, -B, -C and -D, each of which contains a single EPIYA motif, have been identified in the EPIYA-repeat region (Higashi et al, 2002b(Higashi et al, , 2005Naito et al, 2006) ( Figure 1). The representative CagA proteins of Western H. pylori isolates (Western CagA) possess the EPIYA-A and EPIYA-B segments followed by the EPIYA-C segment.…”

Strategy To Characterize the Number and Type of Repeating EPIYA Phosphorylation Motifs in the Carboxyl Terminus of CagA Protein inHelicobacter pyloriClinical Isolates

“…More specifically, tyrosine-phosphorylated CagA seems to bind and deregulate the activity of Src homology 2-containing protein tyrosine phosphatase 2 via the Western CagA-specific EPIYA-C or East Asian CagA-specific EPIYA-D site and of carboxyl-terminal Src kinase via the EPIYA-A or EPIYA-B site (22). In parallel, CagA EPIYA motifs have been suggested to play an essential role for the tethering of CagA to the membrane in a phosphorylation-independent manner (18). Consequently, CagA variability with reference to EPIYA motifs may play an important role in H. pylori pathogenesis.…”