Common infection strategies of human and plant pathogens

Signal transduction network in eukaryotes also comprises of the phospholipid-based signaling. Phosphoinositides (PI) are phospholipids that play a key role in determining membrane identity and trafficking. Phosphatidylinositol 3-phosphate [PI(3)P] has recently emerged as a molecule of interest in diverse host-microbe interactions. Specifically, the levels of PI(3)P is exploited by pathogens to establish intracellular infections. Eukaryotic pathogens such as the apicomplexan P. falciparum and the plant pathogenic oomycetes P. infestans appear to utilize PI(3)P at the host plasma membrane and the ER membrane, respectively to modulate trafficking for both secretion and pathogenesis. P. infestans spores germinate to form infection structures called haustorium to infect plant cells. P. falciparum parasites invade mature human erythrocytes and develop within a membranous structure called the parasitophorous vacuole (PV). Virulence effectors are then exported from the parasite to modulate the host system. Interestingly, both P. falciparum and P. infestans utilize a host-targeting (HT) motif on secretory proteins to deliver these effectors across the haustorial or vacuolar membrane to enter host cytoplasm. The plasmodial HT motif (RxLxE/D/Q) and the P. infestans RxLR-dEER motif display striking sequence similarity and are functionally interchangeable. Importantly, the affinities of both the HT signals to PI(3)P ultimately determine successful invasion (in the case of P. infestans) and pathogenesis (in the case of P. falciparum). I am interested in understanding the phosphoinositide-based signaling mechanisms in eukaryotic pathogens like P. falciparum and P. infestans.