ORCID Profile
0000-0002-3788-1687
Current Organisations
Diamond Light Source
,
University of Southampton
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Publisher: Cold Spring Harbor Laboratory
Date: 11-10-2022
DOI: 10.1101/2022.10.10.511592
Abstract: Engineering expanded effector recognition in plant immune receptors is a promising prospect for generating new disease resistant crop varieties. However, modification of plant NLR receptors has proven challenging due to the lack of understanding of their context as part of complex immune systems. Here, we demonstrate a new avenue for NLR-mediated engineering that exploits the allelic ersity in the Pik NLR pair to allow for the generation of receptors with expanded recognition specificities, which would otherwise result in constitutive cell death. This work lays the foundation for the incorporation of new effector recognition motifs into the Pik system and advances the development of designer NLRs that can be tailored to specific secreted pathogen signatures. Engineering the plant immune system offers genetic solutions to mitigate crop diseases caused by erse agriculturally significant pathogens and pests. Modification of intracellular plant immune receptors of the nucleotide-binding leucine rich repeat (NLRs) superfamily for expanded recognition of pathogen virulence proteins (effectors) is a promising approach for engineering novel disease resistance. However, engineering can cause NLR autoactivation, resulting in constitutive defence responses that are deleterious to the plant. This may be due to plant NLRs associating in highly complex signalling networks that co-evolve together, and changes through breeding or genetic modification can generate incompatible combinations, resulting in autoimmune phenotypes. We have previously shown how alleles of the rice NLR pair Pik have differentially co-evolved, and how sensor/helper mismatching between non-co-evolved alleles triggers constitutive activation and cell death (De la Concepcion et al., 2021b). Here, we dissect incompatibility determinants in the Pik pair and found that HMA domains integrated in Pik-1 not only evolved to bind pathogen effectors but also likely co-evolved with other NLR domains to maintain immune homeostasis. This explains why changes in integrated domains can lead to autoactivation. We then used this knowledge to facilitate engineering of new effector recognition specificities overcoming initial autoimmune penalties. We show that by mismatching alleles of the rice sensor and helper NLRs Pik-1 and Pik-2, we can enable the integration of synthetic HMA domains with novel and enhanced recognition of an effector from the rice blast fungus. Taken together, our results reveal a new strategy for engineering NLRs, which has the potential to allow an expanded set of integrations and therefore new disease resistance specificities in plants.
Publisher: Oxford University Press (OUP)
Date: 24-07-2023
Abstract: Engineering the plant immune system offers genetic solutions to mitigate crop diseases caused by erse agriculturally significant pathogens and pests. Modification of intracellular plant immune receptors of the nucleotide-binding leucine-rich repeat (NLR) receptor superfamily for expanded recognition of pathogen virulence proteins (effectors) is a promising approach for engineering disease resistance. However, engineering can cause NLR autoactivation, resulting in constitutive defense responses that are deleterious to the plant. This may be due to plant NLRs associating in highly complex signaling networks that coevolve together, and changes through breeding or genetic modification can generate incompatible combinations, resulting in autoimmune phenotypes. The sensor and helper NLRs of the rice (Oryza sativa) NLR pair Pik have coevolved, and mismatching between noncoevolved alleles triggers constitutive activation and cell death. This limits the extent to which protein modifications can be used to engineer pathogen recognition and enhance disease resistance mediated by these NLRs. Here, we dissected incompatibility determinants in the Pik pair in Nicotiana benthamiana and found that heavy metal–associated (HMA) domains integrated in Pik-1 not only evolved to bind pathogen effectors but also likely coevolved with other NLR domains to maintain immune homeostasis. This explains why changes in integrated domains can lead to autoactivation. We then used this knowledge to facilitate engineering of new effector recognition specificities, overcoming initial autoimmune penalties. We show that by mismatching alleles of the rice sensor and helper NLRs Pik-1 and Pik-2, we can enable the integration of synthetic domains with novel and enhanced recognition specificities. Taken together, our results reveal a strategy for engineering NLRs, which has the potential to allow an expanded set of integrations and therefore new disease resistance specificities in plants.
Publisher: Cold Spring Harbor Laboratory
Date: 23-05-2023
DOI: 10.1101/2023.05.23.541926
Abstract: The marine cyanobacterium Prochlorococcus is a main contributor to global photosynthesis, whilst being limited by iron availability. Cyanobacterial genomes typically encode two different types of FutA iron binding proteins: periplasmic FutA2 ABC transporter subunits bind ferric (Fe 3+ ), while cytosolic FutA1 binds ferrous (Fe 2+ ). Owing to their small size and their economized genome Prochlorococcus ecotypes typically possess a single futA gene. How the encoded FutA protein might bind different Fe oxidation states was previously unknown. Here we use structural biology techniques at room temperature to probe the dynamic behavior of FutA. Neutron diffraction confirmed four negatively charged tyrosinates, that together with a solvent molecule coordinate iron in trigonal bipyramidal geometry. Positioning of the positively charged Arg103 side chain in the second coordination shell was consistent with an overall charge-neutral ferric binding state in structures determined by neutron diffraction and serial femtosecond crystallography. Conventional rotation X-ray crystallography using a home source revealed X-ray induced photoreduction of the iron center with observation of the ferrous binding state here, an additional positioning of the Arg203 side chain in the second coordination shell maintained an overall charge neutral ferrous binding site. Room temperature dose series using serial synchrotron crystallography and an XFEL X-ray pump-probe approach capture the transition between ferric and ferrous states, revealing how Arg203 operates as a switch to accommodate the different iron oxidation states. This switching ability of the Prochlorococcus FutA protein may reflect ecological adaptation by genome streamlining and loss of specialized FutA proteins. Oceanic primary production by marine cyanobacteria is a main contributor to carbon and nitrogen fixation. Prochlorococcus is the most abundant photosynthetic organism on Earth, with an annual carbon fixation comparable to the net global primary production from agriculture. Its remarkable ecological success is based on the ability to thrive in low nutrient waters. To manage iron limitation, Prochlorococcus possesses the FutA protein for iron uptake and homeostasis. We reveal a switch in the FutA protein that allows it to accommodate binding of iron in either the ferric (Fe 3+ ) or ferrous (Fe 2+ ) state using structural biology techniques at room temperature and provide a plausible mechanism for FutA as a bifunctional redox state sensing protein.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jack Stubbs.