A Phytophthora capsiciRXLR effector manipulates plant immunity by targeting RAB proteins and disturbing the protein trafficking pathway

Abstract

Unlike mammals, plants lack internal specialized immune cells to defend against pathogens. Instead, they rely on the innate immunity of the individual cells and have evolved a sophisticated signal transduction network to respond to pathogens (Jones & Dangl, 2006). For example, protein receptors localized on the plant cell membrane can detect conserved pathogen-associated molecular patterns (PAMPs), leading to an immune response cascade, such as the rapid release of reactive oxygen species (Tsuda & Katagiri, 2010). Plants also secrete defence molecules into apoplasts to combat pathogen invasion (Doehlemann & Hemetsberger, 2013).Pathogens can secrete effectors to overcome the host immunity and establish an infection (Dou & Zhou, 2012;Latijnhouwers

An RXLR effector targets ER-Golgi interface to induce ER stress and necrotic cell death

“…Due to the rapid induction of cell death by Pc12, cytosolic Pc12 expression was observed in the early time point following 1% ethanol spray treatment to determine its subcellular localization (Figure 5A). Interestingly, in contrast to the previously studied isoform (Li et al 2022), the Pc12 proteins are defused in the cytoplasm with preferential accumulation closer to the ER and Golgi (Figure 5A). We attempted to confirm the Pc12 localization in the vicinity of the ER and Golgi apparatus by co-expressing ER marker (Chakrabarty et al 2007) and Golgi marker (Nelson et al 2007, Park et al 2017.…”

“…The hypervariable C-terminal region of Rab proteins contributes to the specificity of membrane delivery for certain Rab proteins (Figueroa et al 2001; Pylypenko et al 2018). Previously, a Pc12 isoform was identified that interacts with a Rab 13 subfamily isoform localizes to the ER (Li et al 2022). To gain insight into the localization of Pc12 within host cells, we transiently expressed EGFP-Pc12 and EGFP-Pc12ΔC5 (without the signal peptide and RXLR-EER motifs) under the control of an ethanol-inducible promoter.…”

“…Previously, one of Pc12 homologs was shown to induce cell death by its transient expression in N. benthamiana (Li et al 2019) and, interestingly, this isoform also interacts with one of the Rab 13 protein (Rab 13-4) that colocalizes with the ER and nucleus (Li et al 2022). To validate weather Pc12 interacts with Rab proteins, we performed immunoprecipitation and mass spectrometry (IP-MS) using Pc12 and Pc12ΔC5.…”

“…Dysfunctional Rab proteins in vesicle trafficking can result in ER stress due to improper protein compartmentation (Kiral et al, 2018). Several effectors of various pathogens are known to suppress antimicrobial protein secretion (PR1 and PDF1.2) or subvert vesicle movement toward the pathogen’s focal area by targeting Rab proteins (Tomczynska et al 2018; Pandey et al 2021; Li et al 2022). However, it remains elusive how the RXLR effector leads to ER stress-induced cell death by disrupting Rab proteins in vesicle trafficking.…”

An oomycete effector co-opts a host RabGAP protein to remodel pathogen interface and subvert defense-related secretion

“…Rab GTPases (Rabs) are integral to vesicle trafficking and immunity, mediating the movement and fusion of vesicles with membrane compartments 13 . While the immune functions of plant Rabs remain largely unknown, members of the Rab8 and Rab11 have been identified to contribute to pathogen resistance by facilitating defense-related secretion 3,4,14 . Rabs function as molecular switches cycling between GTP-bound active and GDP-bound inactive states.…”