Plant and prokaryotic TIR domains generate distinct cyclic ADPR NADase products

Abstract

Toll/interleukin-1 receptor (TIR) domain proteins function in cell death and immunity. In plants and bacteria, TIR domains are often enzymes that produce isomers of cyclic adenosine 5′-diphosphate–ribose (cADPR) as putative immune signaling molecules. The identity and functional conservation of cADPR isomer signals is unclear. A previous report found that a plant TIR could cross-activate the prokaryotic Thoeris TIR–immune system, suggesting the conservation of plant and prokaryotic TIR-immune signals. Here, we generate autoactive Thoeris TIRs and test the converse hypothesis: Do prokaryotic Thoeris TIRs also cross-activate plant TIR immunity? Using in planta and in vitro assays, we find that Thoeris and plant TIRs generate overlapping sets of cADPR isomers and further clarify how plant and Thoeris TIRs activate the Thoeris system via producing 3′cADPR. This study demonstrates that the TIR signaling requirements for plant and prokaryotic immune systems are distinct and that TIRs across kingdoms generate a diversity of small-molecule products.

Toxin-mediated depletion of nicotinamide dinucleotides drives persister formation in a human pathogen

“…And does the salvage pathway repressor NrtR distinguish between ADPR-1P and its cognate ligand ADPR 32 ? TIR domain NADases involved in cell death signaling and abortive infection produce cyclic derivatives of ADP-ribose as potent signaling molecules 18,57 . It will be interesting to test if ADPR-1P has similar properties or if RES domain phosphorylases operate on the simple logic of depleting NAD + pools.…”

Plant NLR immunity activation and execution: a biochemical perspective

“…Besides the TIR-domain NLR receptors (TNLs) conferring ETI in dicot species, plants also express smaller TIR-NB and TIRonly proteins with immune-related activities [34,[113][114][115][116]. In plant transient expression assays, individual TIR domains taken from various TNLs or a natural truncated TIR-domain Resistance protein (Arabidopsis RBA1) induced cell death [34,107,108,113,117]. Tested TIRs required TIR-TIR self-association and an intact NADase catalytic site to generate NAD + hydrolysis products nicotinamide (NAM) and two cyclic ADPR variants in vitro and in vivo [107,108].…”

“…The best characterized mobile and/or distally produced immune signals in plants are an induced stress metabolite, royalsocietypublishing.org/journal/rsob Open Biol. 14: 230387 N-hydroxypipecolic acid (NHP), and the biotic stress phytohormone salicylic acid (SA) [117,[150][151][152] (figure 3). Additionally, host apoplastic proteins and peptides called phytocytokines are important signals for transmission of immune and damage responses between cells and tissues [153,154].…”

Paired plant immune CHS3-CSA1 receptor alleles form distinct hetero-oligomeric complexes

“…S4, B and C). We made these mutations based on either previous studies reported or the charge and side chain of amino acid ( 50 , 51 ) (table S1). Consistent with published studies on plant TNLs, mutating two conserved residues (SH to AA) in the αA helix of CSA1 TIR from clade 2 Per-0 or clade 3 Ws-2 completely abolished CHS3-CSA1 pair–mediated cell death (Fig.…”