Host-targeting protein 1 (SpHtp1) from the oomycete Saprolegnia parasitica translocates specifically into fish cells in a tyrosine-O-sulphate–dependent manner

Abstract

The eukaryotic oomycetes, or water molds, contain several species that are devastating pathogens of plants and animals. During infection, oomycetes translocate effector proteins into host cells, where they interfere with host-defense responses. For several oomycete effectors (i.e., the RxLR-effectors) it has been shown that their N-terminal polypeptides are important for the delivery into the host. Here we demonstrate that the putative RxLR-like effector, host-targeting protein 1 (SpHtp1), from the fish pathogen Saprolegnia parasitica translocates specifically inside host cells. We further demonstrate that cellsurface binding and uptake of this effector protein is mediated by an interaction with tyrosine-O-sulfate-modified cell-surface molecules and not via phospholipids, as has been reported for RxLR-effectors from plant pathogenic oomycetes. These results reveal an effector translocation route based on tyrosine-O-sulfate binding, which could be highly relevant for a wide range of host-microbe interactions.protein translocation | Phytophthora | Plasmodium

Mechanisms and Evolution of Virulence in Oomycetes

“…Fungal effectors also appear to enter via a pathogen-independent mechanism that may involve RxLR-like motifs and binding to PI3P (46,74,80). On the other hand, an RxLR-like effector from the oomycete fish pathogen Saprolegnia parasitica appears to enter via a pathogen-independent mechanism but utilizes binding to tyrosine sulfate rather than PI3P (124). Further careful work is needed to clarify the situation.…”

Role of Pathogen-Derived Cell Wall Carbohydrates and Prostaglandin E 2 in Immune Response and Suppression of Fish Immunity by the Oomycete Saprolegnia parasitica

“…The mycelium is capable of producing and releasing motile zoospores that, after encysting, can germinate upon attachment to a new host and subsequently form new mycelial mats (4). Recently, effector proteins with the capability of self-translocating into fish host cells and proteases capable of degrading serum IgM have been described in S. parasitica (6,7), giving some insight into the virulence factors employed by animal-pathogenic oomycetes.…”

Avirulence Protein 3a (AVR3a) from the Potato Pathogen Phytophthora infestans Forms Homodimers through Its Predicted Translocation Region and Does Not Specifically Bind Phospholipids

“…Therefore, we would question the biological relevance that PLP binding plays for AVR3a. As an alternative, we recently discovered that a putative RxLR-like effector protein from the fish pathogenic oomycete Saprolegnia parasitica is translocated into fish cells via binding to a receptor that is tyrosine O-sulfated (29). It will be interesting to investigate whether RxLR proteins from plant pathogenic oomycetes use a similar strategy to enter plant cells.…”