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Hulin, M.

Publications and source records attributed to Hulin, M..

3 recordsLinked to original sources
bioRxiv2026

It takes two: A Widespread Temperate Bacteriophage Contributes to Regulation of the Type III Secretion System in Pseudomonas syringae

O_LIThe Pseudomonas syringae species complex includes major crop pathogens that use a type III secretion system (T3SS) to inject effectors into plant cells, suppressing immunity and promoting disease. C_LIO_LIThe cherry canker pathogen Pseudomonas amygdali pv. morsprunorum (Pam) carries the effector gene hopAR1 on a prophage, PamPP1, which belongs to a novel Caudoviricetes family widespread across the P. syringae complex and likely acquired before pathovar divergence. C_LIO_LIDeletion of PamPP1 shows that this prophage enhances Pam virulence independently of hopAR1, instead it alters the T3SS operon expression both in vitro and in planta. C_LIO_LIThese prophage-driven transcriptional changes likely reshape Pams interaction with plant immunity, highlighting how bacteriophages rewire bacterial transcriptomes and contribute to the evolution and emergence of plant diseases. C_LI

microbiology↗
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↗
bioRxiv2022

Pangenomics facilitated with structural analysis reveals host NAD+ manipulation as a major virulence activity of bacterial effectors

Nicotinamide adenine dinucleotide (NAD+) has emerged as a key component in prokaryotic and eukaryotic immune systems and the recent discovery that Toll/interleukin-1 receptor (TIR) proteins function as NAD+ hydrolases (NADase) link NAD+-derived small molecules with immune signalling. We investigated pathogen manipulation of host NAD+ metabolism as a virulence strategy. Using the pangenome of the model bacterial pathogen Pseudomonas syringae, we conducted a structure-based similarity search from 35,000 orthogroups for type III effectors (T3Es) with potential NADase activity. Thirteen T3Es, including five newly identified candidates, were identified that possess domain(s) characteristic of seven NAD+-hydrolyzing enzyme families. Most P. syringae strains that depend on the Type III secretion system to cause disease, encode at least one NAD+-manipulating T3E, and many have several. We experimentally confirmed the type III-dependent secretion of a novel T3E, named HopBY, which shows structural similarity to both TIR and adenosine diphosphate ribose (ADPR) cyclase. Homologs of HopBY were predicted to be type VI effectors in diverse bacterial species, indicating potential recruitment of this activity by microbial proteins secreted during various interspecies interactions. HopBY efficiently hydrolyzes NAD+ and specifically produces 2cADPR, which can also be produced by TIR immune receptors of plants and other bacteria. Intriguingly, this effector promoted bacterial virulence, indicating that 2cADPR may not be the signalling molecule that directly initiates immunity. This study highlights a host-pathogen battle ground centred around NAD+ metabolism and provides insight into the NAD+-derived molecules involved in plant immunity. Significance statementNAD+ metabolism plays a crucial role in plant and bacterial immunity. However, the diversity and scope of NAD+ processing steps in immune signalling remain unclear. Furthermore, whether pathogens can manipulate NAD+ metabolism to promote virulence is unknown. By conducting a pangenomic screen of the plant pathogen P. syringae, we found 13 type III effectors that potentially possess NADase activities, indicating that NAD+ manipulation is an important virulence mechanism. Further characterization of a newly identified effector HopBY showed that it produces a cyclic ADP-ribose isomer (2cADPR) and promotes bacterial infection and symptom development. This study clarifies the role of 2cADPR in immune signalling and provides an example of effectors as useful molecular probes to understand immunity.

plant biology↗