How do evolutionarily conserved pathogen effectors maintain structural stability while engaging diverse host targets? In a new study published in Molecular Plant Microbe Interactions® (MPMI), researchers at the University of Pretoria's Forestry and Agricultural Biotechnology Institute (FABI) define a conserved subset of Phytophthora RxLR effectors in which short linear motifs (SLiMs) are embedded within folded WY domain cores.
Phytophthora species rank among the world's most destructive plant pathogens, causing devastating crop diseases through RxLR effectors—proteins delivered into plant cells to manipulate immune responses. In this study , published in MPMI, researchers combined computational modeling and structural analyses with functional assays in tobacco (Nicotiana spp.) and potato (Solanum spp.) plants. Their analyses identified a subset of these effectors in which short linear motifs (SLiMs), typically found in disordered protein regions, are embedded within a stable WY-like helical core. This arrangement preserves domain integrity while enabling potential interactions with host immune components. Tests of Phytophthora nicotianae RxLR6 further showed that it activates defense networks, pointing to a more nuanced role in immune modulation.
Lead author Brenda Salasini said: "What excites me is that this study identifies an architectural feature within a subset of conserved Phytophthora RxLR effectors. Specifically, we show that a stable WY-like core can accommodate SLiMs within the folded domain." She added, "This departs from the usual expectation that SLiMs operate primarily in disordered regions and offers a structural basis for thinking about how conserved effectors engage host immune related processes while preserving domain integrity."
Phytophthora species ravage global agriculture, but this novel link between effector architecture and immune activity reframes pathogen strategies. The findings challenge SLiM dogma and spotlight structured domains as interaction scaffolds.
The team explained that the research impacts plant pathology, structural biology, and host–pathogen interaction studies as it connects effector structure to immune-related function in a mechanistic way. The team added, "The research shifts how interaction sites are identified, how conserved regions are interpreted, and how functional experiments are designed, particularly by encouraging closer examination of structured effector cores rather than focusing exclusively on disordered regions."
For additional details, read " Structural Insights into WY Domain SLiM-Containing Conserved RxLR Effectors: A Case Study of Five Important Phytophthora Species ," published in MPMI.
