scholarly journals Substrate channeling in oxylipin biosynthesis through a protein complex in the plastid envelope of Arabidopsis thaliana

2018 ◽  
Author(s):  
Stephan Pollmann ◽  
Armin Springer ◽  
Sachin Rustgi ◽  
Diter von Wettstein ◽  
ChulHee Kang ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Insect Pests ◽  
Fine Tuning ◽  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Cytochrome P450 Enzymes ◽  
Defense Compounds ◽  
Plastid Envelope ◽  
Volatile Aldehydes ◽  
Abiotic Stimuli

ABSTRACTOxygenated membrane fatty acid derivatives dubbed oxylipins play important roles in the plant’s defense against biotic and abiotic cues. Plants challenged by insect pests, for example, synthesize a blend of different defense compounds that, amongst others, comprise volatile aldehydes and jasmonic acid (JA). Because all oxylipins are derived from the same pathway, we asked how their synthesis might be regulated and focused on two closely related, atypical cytochrome P450 enzymes designated CYP74A and CYP74B, i.e., allene oxide synthase (AOS) and hydroperoxide lyase (HPL). Both enzymes compete for the same substrate but give rise to different products. While the final product of the AOS branch is JA, those of the HPL branch comprise volatile aldehydes and alcohols. AOS and HPL are plastid envelope enzymes in Arabidopsis thaliana but accumulate at different locations. Biochemical experiments identified AOS as constituent of complexes also containing lipoxygenase 2 (LOX2) and allene oxide cyclase (AOC), which catalyze consecutive steps in JA precursor biosynthesis, while excluding the concurrent HPL reaction. Based on published X-ray data, the structure of this complex could be modelled and amino acids involved in catalysis and subunit interactions identified. Genetic studies identified the microRNA 319 (miR319)-regulated clade of TCP (TEOSINTE BRANCHED/CYCLOIDEA/PCF) transcription factor genes and CORONATINE INSENSITIVE 1 (COI1) to control JA production through the AOS-LOX2-AOC2 complex. Together, our results define a molecular branch point in oxylipin biosynthesis that allows fine-tuning the plant’s defense machinery in response to biotic and abiotic stimuli.

scholarly journals ALLENE OXIDE SYNTHASE and HYDROPEROXIDE LYASE, Two Non-Canonical Cytochrome P450s in Arabidopsis thaliana and Their Different Roles in Plant Defense

2019 ◽  
Vol 20 (12) ◽  
pp. 3064 ◽  
Author(s):  
Sachin Rustgi ◽  
Armin Springer ◽  
ChulHee Kang ◽  
Diter von Wettstein ◽  
Christiane Reinbothe ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Defense ◽  
Metabolic Regulation ◽  
Insect Pests ◽  
Green Leaf Volatiles ◽  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Cytochrome P450 Enzymes ◽  
Oxide Synthase

The channeling of metabolites is an essential step of metabolic regulation in all living organisms. Multifunctional enzymes with defined domains for metabolite compartmentalization are rare, but in many cases, larger assemblies forming multimeric protein complexes operate in defined metabolic shunts. In Arabidopsis thaliana, a multimeric complex was discovered that contains a 13-lipoxygenase and allene oxide synthase (AOS) as well as allene oxide cyclase. All three plant enzymes are localized in chloroplasts, contributing to the biosynthesis of jasmonic acid (JA). JA and its derivatives act as ubiquitous plant defense regulators in responses to both biotic and abiotic stresses. AOS belongs to the superfamily of cytochrome P450 enzymes and is named CYP74A. Another CYP450 in chloroplasts, hydroperoxide lyase (HPL, CYP74B), competes with AOS for the common substrate. The products of the HPL reaction are green leaf volatiles that are involved in the deterrence of insect pests. Both enzymes represent non-canonical CYP450 family members, as they do not depend on O2 and NADPH-dependent CYP450 reductase activities. AOS and HPL activities are crucial for plants to respond to different biotic foes. In this mini-review, we aim to summarize how plants make use of the LOX2–AOS–AOC2 complex in chloroplasts to boost JA biosynthesis over volatile production and how this situation may change in plant communities during mass ingestion by insect pests.

CYP74C3 and CYP74A1, plant cytochrome P450 enzymes whose activity is regulated by detergent micelle association, and proposed new rules for the classification of CYP74 enzymes

2006 ◽  
Vol 34 (6) ◽  
pp. 1223-1227 ◽  
Author(s):  
R.K. Hughes ◽  
E.J. Belfield ◽  
R. Casey
Keyword(s):  
Cytochrome P450 ◽  
Major Effect ◽  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Cytochrome P450 Enzymes ◽  
Oligomeric State ◽  
Product Specificity ◽  
Detergent Micelle ◽  
Sequence Relatedness ◽  
Monomeric Proteins

CYP74C3 (cytochrome P450 subfamily 74C3), an HPL (hydroperoxide lyase) from Medicago truncatula (barrel medic), and CYP74A1, an AOS (allene oxide synthase) from Arabidopsis thaliana, are key membrane-associated P450 enzymes in plant oxylipin metabolism. Both recombinant detergent-free enzymes are monomeric proteins with dual specificity and very low enzyme activity that can be massively activated with detergent. This effect is a result of the formation of a complex between the protein monomer and a single detergent micelle and, in the case of CYP74A1, has a major effect on the substrate specificity of the enzyme. Association with a detergent micelle without an effect on protein oligomeric state represents a new mechanism of activation for membrane-associated P450 enzymes. This may represent a second unifying feature of CYP74 enzymes, in addition to their known differences in reaction mechanism, which separates them functionally from more classical P450 enzymes. Highly concentrated and monodispersed samples of detergent-free CYP74C3 and CYP74A1 proteins should be suitable for structural resolution. On the basis of recent evidence for incorrect assignment of CYP74 function, using the current rules for CYP74 classification based on sequence relatedness, we propose an alternative based on substrate and product specificity for debate and discussion.

Implementing the systems approach in rice pest management : India context

2019 ◽  
Vol 56 (Special Issue) ◽  
pp. 136-142 ◽  
Author(s):  
RK Tanwar ◽  
S Singh ◽  
SP Singh ◽  
Vikas Kumar Kanwar ◽  
Rakesh Kumar ◽  
...  
Keyword(s):  
Systems Approach ◽  
Insect Pests ◽  
Rice Variety ◽  
National Level ◽  
Uttar Pradesh ◽  
Fine Tuning ◽  
Basmati Rice ◽  
Rice Grain ◽  
Integrated Crop Management ◽  
Chemical Pesticides

A basic IPM module for basmati rice as a part of integrated crop management accounting the pest prevalence and the information available from literature has been developed. As the module is location specific and dynamic, therefore needs regular updating and fine tuning depending on the location and pest prevalence. The technology has been successfully validated and implemented during 1998 to 2019 in Pusa Basmati 1, Taraori Basmati, Dehraduni Basmati, Pusa Basmati 1121 in Haryana, Uttar Pradesh and Uttarakhand with little modification and fine tuning. Implementation of the technology resulted in increase in rice grain yield i.e., 21.6% in Pusa Basmati 1 at Shikohpur, in Uttar Pradesh 21.5% in Taraori Basmati at Chhajpur in Haryana, 19.5% in Type 3 in Uttarakhand, 14.5 to 22.7% in Pusa Basmati 1121 in Haryana and 38.2% in Pusa Basmati 1121 in Uttar Pradesh over farmer's practices (FP). In all the basmati rice trials, higher yield as well as Benefit - Cost (B-C) ratio was obtained in IPM as compared to FP. Implementation of IPM led to significant reduction in uses of chemical pesticides. In case of IPM, only 1.46 application of chemical pesticides (103.2 g a.i./ha) were undertaken in Pusa Basmati 1121 against 2.8 application in FP (1214.4 g a.i./ha) at Bambawad, Uttar Pradesh. ICAR-NRRI, Cuttack developed and validated IPM module at Sigmapur (Cuttack, Odisha) non-Basmati rice variety Pooja for four kharif seasons i.e 2010-2013 using standard agronomic practices. The trial resulted in an enhancement of 47.1% yield and 26.47 % B-C ratio over FP. Additional income of Rs. 9857/- per ha was also obtained in IPM over FP. On-Farm trial on validation of IPM module in non-Basmati rice (Pooja variety) under semi deep water conditions conducted in 10 ha during rabi 2017 at Nagapur and Basudeipur villages in Khurda district of Odisha resulted in reduction in the incidence of insect pests and diseases with higher population of natural enemies as compared to FP. Rice yield was recorded 5600 kg ha-1 in IPM as against 4900 kg ha-1 in FP. Recently, ICT based e-pest monitoring and advisory has become an important component for area wise implementation of IPM at state and national level. The programme has been successfully implemented in Odisha during 2010 and 2011 under RKVY. Implementation of the programme had resulted successful management of swarming caterpillar in 13 rice growing districts of Odisha during kharif 2010 and 2011.

scholarly journals Seed Gamma Irradiation of Arabidopsis thaliana ABA-Mutant Lines Alters Germination and Does Not Inhibit the Photosynthetic Efficiency of Juvenile Plants

Dose-Response ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 155932582097924
Author(s):  
Darya Babina ◽  
Marina Podobed ◽  
Ekaterina Bondarenko ◽  
Elizaveta Kazakova ◽  
Sofia Bitarishvili ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Growth Response ◽  
Dose Range ◽  
Fine Tuning ◽  
Plant Tolerance ◽  
Inhibitory Effects ◽  
Γ Irradiation ◽  
Photosynthetic Responses ◽  
Mutant Lines

Plant growth response to γ-irradiation includes stimulating or inhibitory effects depending on plant species, dose applied, stage of ontogeny and other factors. Previous studies showed that responses to irradiation could depend on ABA accumulation and signaling. To elucidate the role of ABA in growth and photosynthetic responses to irradiation, lines Col-8, abi3-8 and aba3 -1 of Arabidopsis thaliana were used. Seeds were γ-irradiated using 60Co in the dose range 50-150 Gy. It was revealed that the dose of 150 Gy affected germination parameters of aba3 -1 and Col-8 lines, while abi3-8 line was the most resistant to the studied doses and even showed faster germination at early hours after γ-irradiation at 50 Gy. These results suggest that susceptibility to ABA is probably more important for growth response to γ-irradiation than ABA synthesis. The photosynthetic functioning of 16-day-old plants mainly was not disturbed by γ-irradiation of seeds, and no indication of photosystem II photoinhibition was noticed, revealing the robustness of the photosynthetic system of A. thaliana. Glutathione peroxidase activity and ABA concentrations in plant tissues were not affected in the studied dose range. These results contribute to the understanding of germination and photosynthesis fine-tuning and of mechanisms of plant tolerance to ionizing radiation.

scholarly journals Programmed chloroplast destruction during leaf senescence involves 13-lipoxygenase (13-LOX)

2016 ◽  
Vol 113 (12) ◽  
pp. 3383-3388 ◽  
Author(s):  
Armin Springer ◽  
ChulHee Kang ◽  
Sachin Rustgi ◽  
Diter von Wettstein ◽  
Christiane Reinbothe ◽  
...  
Keyword(s):  
Leaf Senescence ◽  
Critical Role ◽  
Transit Peptide ◽  
Physiological Changes ◽  
Pathogen Defense ◽  
Chloroplast Transit Peptide ◽  
Selective Destruction ◽  
Plastid Envelope ◽  
Volatile Aldehydes

Leaf senescence is the terminal stage in the development of perennial plants. Massive physiological changes occur that lead to the shut down of photosynthesis and a cessation of growth. Leaf senescence involves the selective destruction of the chloroplast as the site of photosynthesis. Here, we show that 13-lipoxygenase (13-LOX) accomplishes a key role in the destruction of chloroplasts in senescing plants and propose a critical role of its NH2-terminal chloroplast transit peptide. The 13-LOX enzyme identified here accumulated in the plastid envelope and catalyzed the dioxygenation of unsaturated membrane fatty acids, leading to a selective destruction of the chloroplast and the release of stromal constituents. Because 13-LOX pathway products comprise compounds involved in insect deterrence and pathogen defense (volatile aldehydes and oxylipins), a mechanism of unmolested nitrogen and carbon relocation is suggested that occurs from leaves to seeds and roots during fall.

Allene oxide synthase and hydroperoxide lyase product accumulation in Artemisia species

Plant Science ◽  
2005 ◽  
Vol 169 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Meshack Afitlhile ◽  
Hirotada Fukushige ◽  
Charles McCraken ◽  
David Hildebrand
Keyword(s):  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Artemisia Species ◽  
Oxide Synthase ◽  
Product Accumulation

scholarly journals Characterization of a novel eukaryotic ATP/ADP translocator located in the plastid envelope of Arabidopsis thaliana L.

1997 ◽  
Vol 11 (1) ◽  
pp. 73-82 ◽  
Author(s):  
H.E. Neuhaus ◽  
E. Thom ◽  
T. Mohlmann ◽  
M. Steup ◽  
K. Kampfenkel
Keyword(s):  
Arabidopsis Thaliana ◽  
Plastid Envelope

scholarly journals Characterization of Medicago truncatula (barrel medic) hydroperoxide lyase (CYP74C3), a water-soluble detergent-free cytochrome P450 monomer whose biological activity is defined by monomer–micelle association

2006 ◽  
Vol 395 (3) ◽  
pp. 641-652 ◽  
Author(s):  
Richard K. Hughes ◽  
Eric J. Belfield ◽  
Mylrajan Muthusamay ◽  
Anuja Khan ◽  
Arthur Rowe ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Cytochrome P450 ◽  
Medicago Truncatula ◽  
Water Soluble ◽  
Hydroperoxide Lyase ◽  
Cytochrome P450 Enzyme ◽  
Cytochrome P450 Enzymes ◽  
P450 Enzyme ◽  
Detergent Micelles

We describe the detailed biochemical characterization of CYP74C3 (cytochrome P450 subfamily 74C3), a recombinant plant cytochrome P450 enzyme with HPL (hydroperoxide lyase) activity from Medicago truncatula (barrel medic). Steady-state kinetic parameters, substrate and product specificities, RZ (Reinheitszahl or purity index), molar absorption coefficient, haem content, and new ligands for an HPL are reported. We show on the basis of gel filtration, sedimentation velocity (sedimentation coefficient distribution) and sedimentation equilibrium (molecular mass) analyses that CYP74C3 has low enzyme activity as a detergent-free, water-soluble, monomer. The enzyme activity can be completely restored by re-activation with detergent micelles, but not detergent monomers. Corresponding changes in the spin state equilibrium, and probably co-ordination of the haem iron, are novel for cytochrome P450 enzymes and suggest that detergent micelles have a subtle effect on protein conformation, rather than substrate presentation, which is sufficient to improve substrate binding and catalytic-centre activity by an order of magnitude. The kcat/Km of up to 1.6×108 M−1·s−1 is among the highest recorded, which is remarkable for an enzyme whose reaction mechanism involves the scission of a C–C bond. We carried out both kinetic and biophysical studies to demonstrate that this effect is a result of the formation of a complex between a protein monomer and a single detergent micelle. Association with a detergent micelle rather than oligomeric state represents a new mechanism of activation for membrane-associated cytochrome P450 enzymes. Highly concentrated and monodispersed samples of detergent-free CYP74C3 protein may be well suited for the purposes of crystallization and structural resolution of the first plant cytochrome P450 enzyme.

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