Pseudomonas syringae HopN1 Binds Plant VAP12 and a Rho-GTPase, Suggesting a Role in Membrane-Associated Processes
Charlotte Brinkmann1, Jennifer Bortlik1,2, Frederik Börnke1,3
1Plant Metabolism Group, Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), Großbeeren, Germany.
Contact (Thousand Oaks (Ventura County, Calif.))
|September 8, 2025
Summary
Bacterial type III effector proteins (T3Es) mimic host FFAT motifs to interact with VAMP-associated proteins (VAPs). Pseudomonas syringae
Area of Science:
- Microbiology
- Plant Pathology
- Molecular Biology
Background:
- Gram-negative bacterial pathogens use type III effector proteins (T3Es) to manipulate host cells and evade immunity.
- Some T3Es mimic eukaryotic FFAT (two phenylalanines in an acidic tract) motifs, interacting with VAMP-associated proteins (VAPs) to target host membranes.
- The role and prevalence of FFAT mimicry in bacterial pathogenesis are not well understood.
Purpose of the Study:
- To investigate FFAT motif mimicry in T3Es of the plant pathogen *Pseudomonas syringae* pv. *tomato* (Pst) DC3000.
- To characterize the interaction of the Pst T3E HopN1 with host proteins.
Main Methods:
- Bioinformatic analysis of Pst DC3000 T3Es for FFAT motifs.
- Yeast two-hybrid assays to detect protein-protein interactions.
- In planta co-immunoprecipitation assays to confirm interactions in a host environment.
Main Results:
- The Pst T3E HopN1 contains a functional FFAT motif.
- HopN1 interacts with plant VAP proteins (e.g., VAP12) and a plant RHO-GTPase.
- These interactions suggest a potential role for HopN1 in membrane localization and host manipulation.
Conclusions:
- HopN1 utilizes FFAT mimicry to interact with plant VAPs, potentially influencing its subcellular localization.
- The interaction with RHO-GTPase suggests functional parallels with mammalian YopT.
- Further research is needed to confirm the functional significance of FFAT mimicry and VAP interaction in HopN1 virulence.
Related Concept Videos
01:24Small GTPases - Ras and Rho
5.2K
Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
Three regulatory proteins control their activity:
5.2K
01:14Rab Proteins
5.0K
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
5.0K
01:25Cell Signaling in Plants
6.1K
Plant cells communicate to coordinate their cycle of growth, flowering and fruiting, and activities in roots, shoots, and leaves in response to the changing environmental conditions. Plant signaling is distinct from animal signaling. Plants primarily utilize enzyme-linked receptors, whereas the largest class of cell-surface receptors in animals are G-protein coupled receptors (GPCRs). Unlike animals, receptor tyrosine kinases are rare in plants. Instead, plants have a diverse class of...
6.1K
01:25Rab Cascades
3.4K
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
3.4K
01:33Coat Assembly and GTPases
4.2K
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
4.2K
01:07MAPK Signaling Cascades
8.0K
Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
8.0K