Biology subjects

Johanndrees, O.

Publications and source records attributed to Johanndrees, O..

4 recordsLinked to original sources

bioRxiv2026

Conserved TIR-only proteins drive transcriptional defense and basal immunity in dicot and monocot plants

Toll/interleukin-1/resistance (TIR) domain NADase enzymes signal in plant immunity by producing ribosylated nucleotide second messengers which activate EDS1 dimer-helper NLR pathways to restrict pathogen growth. Members of a small, distinctive group of TIR-only proteins are conserved between dicots and monocots, yet their functions remain poorly understood. Here, we show that conserved TIR-only proteins in Arabidopsis and barley share a fundamental enzymatic role in promoting basal defense against virulent filamentous pathogens, independently of NLR mediated effector-triggered immunity. Metabolite analysis of transiently expressed Arabidopsis and barley TIR-only proteins revealed their capacity to produce ribosylated cyclic nucleotides in vivo. By comparing phenotypes of tir-only and eds1 pad4 CRISPR mutants in the two species, as well as adr1 mutants in barley, we established that the TIR-only proteins promote PAMP-triggered transcriptional defenses associated with pathogen restriction. Barley possesses just one essential TIR-only enzyme and mutations of the two conserved TIR-only members in Arabidopsis were not compensated for by numerous other TIR-domain genes in the basal immune response. These findings suggest that conserved TIR-only proteins make a crucial contribution to TIR basal defense signaling networks of Arabidopsis and barley. We propose that a shared function in transcriptional defense regulation could explain the evolutionary retention of this discrete TIR-only group across monocot and dicot lineages.

plant biology↗

bioRxiv2025

Disulfide bond sculpts a peptide fold that mediates phytocytokine recognition

Precise ligand recognition by closely related leucine-rich repeat receptor kinases (LRR-RKs) is essential for plants to coordinate immunity, development, and environmental adaptation. Here, we show how HAESA-LIKE 3 (HSL3) specifically recognizes the folded, disulfide-stabilized CTNIP/SCREW phytocytokines in Arabidopsis. Quantitative binding assays define a minimal CTNIP4 region required for high-affinity HSL3 interaction and signaling activation. A 2.12 [A] crystal structure of the HSL3-CTNIP4 complex reveals a unique C-terminal receptor pocket that accommodates the peptides cyclic architecture through a combination of hydrophobic and polar contacts, a feature absent in the closely related HAE/HSL LRR-RKs. The cyclic CTNIP4 fold further establishes a largely hydrophobic interface that bridges HSL3 to the SERK co-receptor, forming a distinct activation surface. Together, these structural, biochemical and physiological insights uncover a previously unrecognised mechanism of peptide perception and receptor activation, highlighting how subtle architectural variations enable precise ligand selectivity among highly conserved plant receptor kinases.

plant biology↗

bioRxiv2021

Differential EDS1 requirement for cell death activities of plant TIR-domain proteins

Toll/interleukin-1 Receptor (TIR) domains are integral to immune systems across all domains of life. TIRs exist as single-domain and as larger receptor or adaptor proteins. In plants, TIRs constitute N-terminal domains of nucleotide-binding leucine-rich repeat (NLR) immune receptors. Although TIR-NLR and TIR signaling requires the Enhanced disease susceptibility 1 (EDS1) protein family, TIR domains persist in species that have incomplete or no EDS1 members. To assess whether particular TIR groups appear with EDS1, we searched for TIR-EDS1 co-occurrence patterns. Using a large-scale phylogenetic analysis of TIR domains from 39 algae and land plant species, we identify four conserved TIR groups, two of which are TIR-NLRs present in eudicots and two are more widespread. Presence of one TIR-only protein group is highly correlated with EDS1 and members of this group elicit EDS1-dependent cell death. By contrast, a more widely represented TIR group of TIR-NB-WD40/TPR (TNP) proteins (formerly called XTNX) has at least one member which can induce EDS1-independent cell death. Our data provide a new phylogeny-based plant TIR classification and identify TIR groups that appear to have evolved with and are dependent on EDS1, while others have EDS1-independent activity. One sentence summaryLand plants have evolved four conserved TIR groups

plant biology↗

bioRxiv2021

A conserved regulatory module regulates receptor kinase signaling in immunity and development

Ligand recognition by cell-surface receptors underlies development and immunity in both animals and plants. Modulating receptor signaling is critical for appropriate cellular responses but the mechanisms ensuring this are poorly understood. Here, we show that signaling by plant receptors for pathogen-associated molecular patterns (PAMPs) in immunity and CLAVATA3/EMBRYO SURROUNDING REGION-RELATED peptides (CLEp) in development employ a similar regulatory module. In the absence of ligand, signaling is dampened through association with specific type-2C protein phosphatases (PP2Cs). Upon activation, PAMP and CLEp receptors phosphorylate divergent cytosolic kinases, which, in turn, phosphorylate the phosphatases, thereby promoting their release from the receptor complexes. Our work reveals a regulatory circuit shared between immune and developmental receptor signaling, which may have broader important implications for plant receptor kinase-mediated signaling in general.

plant biology↗