Biology subjects

Derbyshire, P.

Publications and source records attributed to Derbyshire, P..

16 recordsLinked to original sources

bioRxiv2026

A stage-resolved map of dynamic septin interactions required for infection by the rice blast fungus

Septin GTPases are essential cytoskeletal regulators that organize membranes and scaffold protein complexes to control cytokinesis, polarity, and morphogenesis. How septins execute these functions remains poorly understood, and comprehensive, stage-resolved interaction maps are lacking. Here, we define a quantitative, time-resolved septin interactome in the rice blast fungus Magnaporthe oryzae using immunoprecipitation coupled to mass spectrometry. We map more than 350 interactors of septins Sep3, Sep4, Sep5 and Sep6, revealing a dynamic network required for appressorium-mediated plant infection. Beyond canonical roles in cytoskeletal organisation and polarity, septins associate with proteins linked to membrane remodelling, metabolism, and virulence, deployed during host invasion. Integration with ultra-high-throughput yeast two-hybrid analysis defines a high-confidence septin interactome and identifies previously uncharacterised factors, including Msi1, a BAR domain protein required for invasive growth. Together, these findings establish septins as dynamic organisers of infection-related processes and provide a framework for understanding how cytoskeletal scaffolds coordinate fungal pathogenesis.

cell biology↗

bioRxiv2026

Structural basis for the broad recognition specificity of an Arabidopsis immune receptor

Plant nucleotide-binding leucine-rich repeat (NLR) immune receptors typically confer resistance through recognition of specific pathogen effectors. The Arabidopsis NLR WRR4A defies this paradigm by recognizing multiple sequence-divergent effectors from Albugo candida, conferring resistance to multiple pathogen races. Despite minimal sequence similarity, these effectors share a conserved N-terminal ferredoxin-like fold. Through cryo-EM structure determination of two WRR4A resistosomes bound to sequence-distinct effectors, combined with AlphaFold modelling, we reveal a shape-based recognition mechanism: WRR4A engages structurally conserved backbone features of the effectors in a mostly side chain-independent manner, enabling recognition of diverse effectors with similar three-dimensional architectures. These insights guided successful engineering of WRR4A to acquire novel recognition specificity. In addition, analysis of the monomeric WRR4A resting state reveals a distinct domain architecture characteristic of C-JID-containing TIR-NLRs and informs their activation mechanism. This work provides insights into NLR-mediated broad-spectrum recognition and the potential for structure-informed engineering of improved crop resistance.

plant biology↗

bioRxiv2025

A Phosphorelay Circuit Drives Extracellular Alkalinization in Plant Receptor Kinase Signaling

Extracellular alkalinization has long been recognized as a hallmark of plant cell-surface receptor activation, including during pattern-triggered immunity (PTI); yet the mechanisms driving elicitor-induced alkalinization and its role in immune signaling remain unclear. Here, we demonstrate that inhibition of autoinhibited H+-ATPases (AHAs) is required for elicitor-induced extracellular alkalinization. This alkalinization is essential for immune signaling mediated by diverse plasma membrane-localized receptor kinases (RKs) through modulation of ligand-receptor interactions. Notably, RKs transduce elicitor-triggered signaling via BOTRYTIS-INDUCED KINASE 1 (BIK1), which inhibits AHA activity by disrupting AHA-GENERAL REGULATORY FACTOR (GRF) interactions through a conserved phosphorylation event. Interestingly, this pathway is crucial for cell wall damage (CWD) responses involving the RK MALE DISCOVERER 1-INTERACTING RECEPTOR LIKE KINASE 2 (MIK2) and its ligand, SERINE RICH ENDOGENOUS PEPTIDE 18 (SCOOP18). Our findings reveal a conserved phospho-regulatory pathway that governs extracellular alkalinization to coordinate plant immune signaling, offering new insights into plant stress resilience.

plant biology↗

bioRxiv2024

Preventing Inappropriate Signals Pre- and Post-Ligand Perception by a Toggle-Switch Mechanism of ERECTA

Dynamic control of signaling events requires swift regulation of receptors at an active state. By focusing on Arabidopsis ERECTA (ER) receptor kinase, which perceives peptide ligands to control multiple developmental processes, we report a mechanism preventing inappropriate receptor activity. The ER C-terminal tail (ER_CT) functions as an autoinhibitory domain: its removal confers higher kinase activity and hyperactivity during inflorescence and stomatal development. ER_CT is required for the binding of a receptor kinase inhibitor, BKI1, and two U-box E3 ligases PUB30 and PUB31 that inactivate activated ER. We further identify ER_CT as a phosphodomain trans-phosphorylated by the co-receptor BAK1. The phosphorylation impacts the tail structure, likely releasing from autoinhibition. The phosphonull version enhances BKI1 association, whereas the phosphomimetic version promotes PUB30/31 association. Thus, ER_CT acts as an off-on-off toggle switch, facilitating the release of BKI1 inhibition, enabling signal activation, and swiftly turning over the receptors afterwards. Our results elucidate a mechanism fine-tuning receptor signaling via a phosphoswitch module, keeping the receptor at a low basal state and ensuring the robust yet transient activation upon ligand perception. SignificanceCells perceive and process external signals through their cell-surface receptors, whose activity must be tightly maintained to prevent the spread of misinformation. How do plant cells prevent the inappropriate receptor activity? We identify a structural module within the C-terminal tail of the ERECTA (ER_CT), that inhibits the receptor pre- and post-signal activation. The ER_CT comprises of a linker and an -helix. Before activation, ER_CT is autoinhibitory and associates with an inhibitory protein. Ligand perception triggers the transphosphorylation of ER_CT by the co-receptor, which then recruits a degradation machinery to swiftly turn over the activated receptor. Thus, we reveal an off-on-off toggle switch mechanism that finely adjusts the activity of the plant receptor, enabling the precise control over cell signaling.

plant biology↗

bioRxiv2023

The leucine-rich repeat receptor kinase QSK1 is a novel regulator of PRR-RBOHD complex and is employed by the bacterial effector HopF2Pto to modulate plant immunity

Plants detect pathogens using cell-surface pattern recognition receptors (PRRs) like EFR and FLS2, which recognize bacterial EF-Tu and flagellin, respectively. These PRRs, belonging to the leucine-rich repeat receptor kinase (LRR-RK) family, activate the production of reactive oxygen species via the NADPH oxidase RBOHD. The PRR-RBOHD complex is tightly regulated to prevent unwarranted or exaggerated immune responses. However, certain pathogenic effectors can subvert these regulatory mechanisms, thereby suppressing plant immunity. To elucidate the intricate dynamics of the PRR-RBOHD complex, we conducted a comparative co-immunoprecipitation analysis using EFR, FLS2, and RBOHD. We identified QSK1, an LRR-RK, as a novel component of the PRR-RBOHD complex. QSK1 functions as a negative regulator of PRR-triggered immunity (PTI) by downregulating the abundance of FLS2 and EFR. QSK1 is targeted by the bacterial effector HopF2Pto, a mono-ADP ribosyltransferase, resulting in the reduction of FLS2 and EFR levels through both transcriptional and transcription-independent pathways, thereby inhibiting PTI. Furthermore, HopF2Pto reduces transcript levels of PROSCOOP genes encoding important stress-regulated phytocytokines and their receptor MIK2. Importantly, HopF2Pto requires QSK1 for its accumulation and virulence functions within plants. In summary, our results provide novel insights into the mechanism by which HopF2Pto employs QSK1 to desensitize plants to pathogen attack. One Sentence SummaryQSK1, a novel component in the plant immune receptor complex, downregulates these receptors and phytocytokines, and is exploited by bacterial effector HopF2Pto to desensitize plants to pathogen attack.

plant biology↗

bioRxiv2023

Subfamily C7 Raf-like kinases MRK1, RAF26, and RAF39 regulate immune homeostasis and stomatal opening in Arabidopsis thaliana

The calcium-dependent protein kinase CPK28 is a regulator of immune homeostasis in multiple plant species. Here, we used a proteomics approach to uncover CPK28-associated proteins. We found that CPK28 associates with subfamily C7 Raf-like kinases MRK1, RAF26, and RAF39, and trans-phosphorylates RAF26 and RAF39. Metazoan Raf kinases function in mitogen-activated protein kinase (MAPK) cascades as MAPK kinase kinases (MKKKs). Although Raf-like kinases share some features with MKKKs, we found that MRK1, RAF26, and RAF39 are unable to trans-phosphorylate any of the 10 Arabidopsis MKKs. We show that MRK1, RAF26, and RAF39 localize to the cytosol and endomembranes, and we define redundant roles for these kinases in stomatal opening, immune-triggered reactive oxygen species (ROS) production, and resistance to a bacterial pathogen. Overall, our study suggests that C7 Raf-like kinases associate with and are phosphorylated by CPK28, function redundantly in stomatal immunity, and possess substrate specificities distinct from canonical MKKKs.

plant biology↗

bioRxiv2023

The phosphorylation landscape of infection-related development by the rice blast fungus

Many of the worlds most devastating crop diseases are caused by fungal pathogens which elaborate specialized infection structures to invade plant tissue. Here we present a quantitative mass spectrometry-based phosphoproteomic analysis of infection-related development by the rice blast fungus Magnaporthe oryzae, which threatens global food security. We mapped 8,005 phosphosites on 2,062 fungal proteins, revealing major re-wiring of phosphorylation-based signaling cascades during fungal infection. Comparing phosphosite conservation across 41 fungal species reveals phosphorylation signatures specifically associated with biotrophic and hemibiotrophic fungal infection. We then used parallel reaction monitoring to identify phosphoproteins directly regulated by the Pmk1 MAP kinase that controls plant infection by M. oryzae. We define 33 substrates of Pmk1 and show that Pmk1-dependent phosphorylation of a newly identified regulator, Vts1, is required for rice blast disease. Defining the phosphorylation landscape of infection therefore identifies potential therapeutic interventions for control of plant diseases.

plant biology↗

bioRxiv2023

Pathogen protein modularity enables elaborate mimicry of a host phosphatase

Pathogens produce diverse effector proteins to manipulate host cellular processes. However, how functional diversity is generated in an effector repertoire is poorly understood. Many effectors in the devastating plant pathogen Phytophthora contain tandem repeats of the "(L)WY" motif, which are structurally conserved but variable in sequences. Here, we discovered a functional module formed by a specific (L)WY-LWY combination in multiple Phytophthora effectors, which efficiently recruit the Serine/Threonine protein phosphatase 2A (PP2A) core enzyme in plant hosts. Crystal structure of an effector-PP2A complex shows that the (L)WY-LWY module enables hijacking of the host PP2A core enzyme to form functional holoenzymes. While sharing the PP2A-interacting module at the amino terminus, these effectors possess divergent C-terminal LWY units and regulate distinct sets of phosphoproteins in the host. Our results highlight the appropriation of an essential host phosphatase through molecular mimicry by pathogens and diversification promoted by protein modularity in an effector repertoire.

plant biology↗

bioRxiv2023

A GH81-type β-glucan-binding protein facilitates colonization by mutualistic fungi in barley

Cell walls are important interfaces of plant-fungal interactions. Host cell walls act as robust physical and chemical barriers against fungal invaders, making them an essential line of defense. Upon fungal colonization, plants deposit phenolics and callose at the sites of fungal penetration to reinforce their walls and prevent further fungal progression. Alterations in the composition of plant cell walls significantly impact host susceptibility. Furthermore, plants and fungi secrete glycan hydrolases acting on each others cell walls. These enzymes release a wide range of sugar oligomers into the apoplast, some of which trigger the activation of host immunity via host surface receptors. Recent characterization of cell walls from plant-colonizing fungi have emphasized the abundance of {beta}-glucans in different cell wall layers, which makes them suitable targets for recognition. To characterize host components involved in immunity against fungi, we performed a protein pull-down with the biotinylated {beta}-glucan laminarin. Thereby, we identified a glycoside hydrolase family 81-type glucan-binding protein (GBP) as the major {beta}-glucan interactor. Mutation of GBP1 and its only paralogue GBP2 in barley led to decreased colonization by the beneficial root endophytes Serendipita indica and S. vermifera, as well as the arbuscular mycorrhizal fungus Rhizophagus irregularis. The reduction of symbiotic colonization was accompanied by enhanced responses at the host cell wall. Moreover, GBP mutation in barley also increased resistance to fungal infections in roots and leaves by the hemibiotrophic pathogen Bipolaris sorokiniana and the obligate biotrophic pathogen Blumeria graminis f. sp. hordei, respectively. These results indicate that GBP1 is involved in the establishment of symbiotic associations with beneficial fungi, a role that has potentially been appropriated by barley-adapted pathogens. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/536646v1_figu1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@c47957org.highwire.dtl.DTLVardef@fa6727org.highwire.dtl.DTLVardef@18a54d2org.highwire.dtl.DTLVardef@c6b103_HPS_FORMAT_FIGEXP M_FIG C_FIG In BriefGBP1, a family 81 glycoside hydrolase, is an important {beta}-glucan interactor in barley. Mutation of GBP1 and its sole paralogue GBP2 leads to reduced colonization by beneficial root endophytes, AM fungi and pathogens, accompanied by enhanced responses at the plant cell wall. This indicates that GBP1 and {beta}-glucans are compatibility factors involved in the establishment of symbiotic associations with beneficial fungi, a role possibly hijacked by pathogens.

plant biology↗

bioRxiv2021

Perception of a conserved family of plant signalling peptides by the receptor kinase HSL3

Plant genomes encode hundreds of secreted peptides; however, relatively few have been characterised. We report here an uncharacterised, stress-induced family of plant signalling peptides, which we call CTNIPs. Based on the role of the common co-receptor BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED KINASE 1 (BAK1) in CTNIP-induced responses, we identified the orphan receptor kinase HAESA-LIKE 3 (HSL3) as the CTNIP receptor via a proteomics approach. CTNIP binding, ligand-triggered complex formation with BAK1, and induced downstream responses all involve HSL3. Notably, the HSL3-CTNIP signalling module is evolutionarily ancient, predating the divergence of extant angiosperms. The identification of this signalling module will help establish its physiological role and provides a resource to understand further receptor-ligand co-evolution.

plant biology↗

bioRxiv2021

A hetero-oligomeric remorin-receptor complex regulates plant development

Plant growth and development are modulated by both biotic and abiotic stress. Increasing evidence suggests that cellular integration of the corresponding signals occurs within preformed hubs at the plasma membrane called nanodomains. These membrane sub-compartments are organized by multivalent molecular scaffold proteins, such as remorins. Here, we demonstrate that Group 1 remorins form a hetero-oligomeric complex at the plasma membrane. While these remorins are functionally redundant for some pathways their multivalency also allows the recruitment of specific interaction partners. One of them, the receptor-like kinase REMORIN-INTERACTING RECEPTOR 1 (RIR1), that acts redundantly with the closely related receptor NILR2, is specifically recruited by REM1.2 in a phosphorylation-dependent manner. Overlapping developmental phenotypes suggest that the REM/RIR complex regulates key developmental pathways.

plant biology↗

bioRxiv2020

The phagocytosis oxidase/Bem1p (PB1) domain-containing protein PB1CP negatively regulates the NADPH oxidase RBOHD in plant immunity

O_LIPerception of pathogen-associated molecular patterns (PAMPs) by surface-localized pattern-recognition receptors activates RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD) through direct phosphorylation by BOTRYTIS-INDUCED KINASE 1 (BIK1) and induces the production of reactive oxygen species (ROS). ROS have direct antimicrobial properties but also serve as signaling molecules to activate additional defense responses such as stomatal closure. RBOHD activity must be tightly controlled to avoid the detrimental effects of ROS, but little is known about RBOHD downregulation. C_LIO_LITo better understand the regulation of RBOHD, we used co-immunoprecipitation of RBOHD coupled with mass spectrometry analysis to identify RBOHD-associated proteins. C_LIO_LIAmong RBOHD-associated proteins, we identified PHAGOCYTOSIS OXIDASE/ BEM1P (PB1) DOMAIN-CONTAINING PROTEIN (PB1CP). We found that PB1CP negatively regulates RBOHD and the resistance against the fungal pathogen Colletotrichum higginsianum. PB1CP directly interacts with RBOHD in vitro, and PAMP treatment increases the interaction in vivo. PB1CP is localized at the cell periphery and in cytoplasm, but PAMP treatment induces PB1CP relocalization to small endomembrane compartments. PB1CP overexpression reduces plasma membrane localization of RBOHD, suggesting that PB1CP down-regulates RBOHD function by relocalizing it away from the plasma membrane. C_LIO_LIWe reveal a novel negative regulation mechanism of ROS production through the relocalization of RBOHD by PB1CP. C_LI

plant biology↗

bioRxiv2020

Pathogen effector recognition-dependent association of NRG1 with EDS1 and SAG101 in TNL receptor immunity

Plants utilise intracellular nucleotide-binding, leucine-rich repeat (NLR) immune receptors to detect pathogen effectors and activate local and systemic defence. NRG1 and ADR1 "helper" NLRs (RNLs), cooperate with enhanced disease susceptibility 1 (EDS1), senescence-associated gene 101 (SAG101) and phytoalexin-deficient 4 (PAD4) lipase-like proteins to mediate signalling from TIR domain NLR receptors (TNLs). However, the mechanism of RNL/EDS1-family protein cooperation is poorly understood. Here, we provide genetic and molecular evidence for exclusive EDS1/SAG101/NRG1 and EDS1/PAD4/ADR1 co-functions in TNL immunity. Using immunoprecipitation and mass spectrometry, we show effector recognition-dependent association of NRG1 with EDS1 and SAG101, but not PAD4. An EDS1-SAG101 complex associates with NRG1, and EDS1-PAD4 associates with ADR1, only in an immune-activated state. NRG1 requires an intact nucleotide-binding P-loop motif, and EDS1 a functional EP domain and its partner SAG101, for induced association and immunity. Thus, two distinct modules (NRG1/EDS1/SAG101 and ADR1/EDS1/PAD4) are required to execute TNL receptor defence signalling.

plant biology↗

bioRxiv2020

The Arabidopsis E3 ubiquitin ligase PUB4 regulates BIK1 homeostasis and is targeted by a bacterial type-III effector

Plant immunity is tightly controlled by a complex and dynamic regulatory network, which ensures optimal activation upon detection of potential pathogens. Accordingly, each component of this network is a potential target for manipulation by pathogens. Here, we report that RipAC, a type III-secreted effector from the bacterial pathogen Ralstonia solanacearum, targets the plant E3 ubiquitin ligase PUB4 to inhibit pattern-triggered immunity (PTI). PUB4 plays a positive role in PTI by regulating the homeostasis of the central immune kinase BIK1. Before PAMP perception, PUB4 promotes the degradation of non-activated BIK1, while, after PAMP perception, PUB4 contributes to the accumulation of activated BIK1. RipAC leads to BIK1 degradation, which correlates with its PTI-inhibitory activity. RipAC causes a reduction in pathogen-associated molecular pattern (PAMP)-induced PUB4 accumulation and phosphorylation. Our results shed light on the role played by PUB4 in immune regulation, and illustrate an indirect targeting of the immune signalling hub BIK1 by a bacterial effector.

plant biology↗

bioRxiv2020

Large-scale identification of ubiquitination sites on membrane-associated proteins in Arabidopsis thaliana seedlings

Protein phosphorylation and ubiquitination are two of the most abundant forms of post-translational modifications in eukaryotes, regulated by thousands of protein kinases, phosphatases, E3 ubiquitin ligases, and ubiquitin proteases. Although previous studies have catalogued several ubiquitinated proteins in plants (Walton et al., 2016), few membrane-localized proteins have been identified. Receptor kinases (RKs) initiate phosphorylation signal relays that regulate plant growth, development, and stress responses. While the regulatory role of phosphorylation on protein kinase function is well-documented (Couto and Zipfel, 2016), considerably less is known about the role of ubiquitination on protein kinase function, even though protein turnover is critical to their signaling competence and cellular homeostasis. Here we describe the large-scale identification of ubiquitination sites on Arabidopsis proteins associated with or integral to the plasma membrane, including over 100 protein kinases.

plant biology↗

bioRxiv2020

A hierarchical transcriptional network controls appressorium-mediated plant infection by the rice blast fungus Magnaporthe oryzae

Rice blast is a pervasive and devastating disease that threatens rice production across the world. In spite of its importance to global food security, however, the underlying biology of plant infection by the blast fungus Magnaporthe oryzae remains poorly understood. In particular, it is unclear how the fungus elaborates a specialised infection cell, the appressorium, in response to surface signals from the rice leaf. Here, we report the identification of a network of temporally co-regulated transcription factors that act downstream of the Pmk1 mitogen-activated protein kinase pathway to regulate gene expression during appressorium-mediated plant infection. We have functionally characterised this network of transcription factors and demonstrated the operation of a hierarchical transcriptional control system. We show that this tiered regulatory mechanism involves Pmk1-dependent phosphorylation of the Hox7 homeobox transcription factor, which represses hyphal-associated gene expression and simultaneously induces major physiological changes required for appressorium development, including cell cycle arrest, autophagic cell death, turgor generation and melanin biosynthesis. Mst12 then regulates gene functions involved in septin-dependent cytoskeletal re-organisation, polarised exocytosis and effector gene expression necessary for plant tissue invasion.

microbiology↗