Speakers - 2026

Title: Structural Integration of WY Domains and Short Linear Motifs in Conserved RxLR Effectors of Phytophthora

Abstract

The virulence of Phytophthora species is mediated by secreted RxLR effectors that manipulate host immune signalling. Among these, conserved RxLR effectors (CREs) are maintained across species and contribute consistently to pathogenic fitness. Despite their evolutionary conservation, the structural basis underlying their persistence and functional stability remains insufficiently defined.

This study investigates the structural organisation of CREs across five agriculturally important Phytophthora species using comparative in silico analyses. We identified a conserved subset characterised by the integration of WY domains with embedded short linear motifs (SLiMs). While SLiMs are typically associated with intrinsically disordered regions, structural modelling revealed that in these CREs, SLiMs are accommodated within ordered α-helical WY cores without disruption of domain integrity.

To assess the functional relevance of this architectural configuration, we characterised Phytophthora nicotianae RxLR6 (PpRxLR6) as a representative WY–SLiM CRE. Agrobacterium-mediated transient expression assays in Nicotiana and Solanum species demonstrated host immune-associated responses consistent with effector activity. Structural predictions further localised the SLiM within a defined WY helical scaffold, supporting the presence of a structurally embedded interaction interface.

Together, these findings define a conserved structural configuration in which WY domains act as ordered scaffolds for SLiM incorporation. This work refines prevailing models that predominantly associate SLiM function with intrinsic disorder and provides a structural framework for understanding how conserved RxLR effectors maintain functional competence across diverse Phytophthora lineages.

What will the audience take away from presentation?

The audience will:

• Understand the structural organisation of conserved RxLR effectors across multiple Phytophthora species.
• Recognise how short linear motifs can be integrated within ordered protein domains.
• Appreciate how domain architecture contributes to effector stability and host interaction.
• Gain insights into structural modelling approaches applicable to effector biology.
• Identify new perspectives for studying protein–protein interaction interfaces in plant–pathogen systems.

How this can be used:

• Researchers can apply similar structural modelling strategies to analyse effector repertoires in other pathogens.
• Faculty can integrate these findings into advanced plant immunity or molecular plant–microbe interaction courses.
• Structural biologists can use this framework to explore scaffold-based interaction models beyond intrinsic disorder paradigms.
• The work informs experimental design for mapping effector interaction interfaces in host systems.