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Shidore T, Broeckling CD, Kirkwood JS, Long JJ, Miao J, Zhao B, Leach JE, Triplett LR. The effector AvrRxo1 phosphorylates NAD in planta. PLoS Pathog 2017; 13:e1006442. [PMID: 28628666 PMCID: PMC5491322 DOI: 10.1371/journal.ppat.1006442] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 06/29/2017] [Accepted: 06/02/2017] [Indexed: 12/14/2022] Open
Abstract
Gram-negative bacterial pathogens of plants and animals employ type III secreted effectors to suppress innate immunity. Most characterized effectors work through modification of host proteins or transcriptional regulators, although a few are known to modify small molecule targets. The Xanthomonas type III secreted avirulence factor AvrRxo1 is a structural homolog of the zeta toxin family of sugar-nucleotide kinases that suppresses bacterial growth. AvrRxo1 was recently reported to phosphorylate the central metabolite and signaling molecule NAD in vitro, suggesting that the effector might enhance bacterial virulence on plants through manipulation of primary metabolic pathways. In this study, we determine that AvrRxo1 phosphorylates NAD in planta, and that its kinase catalytic sites are necessary for its toxic and resistance-triggering phenotypes. A global metabolomics approach was used to independently identify 3'-NADP as the sole detectable product of AvrRxo1 expression in yeast and bacteria, and NAD kinase activity was confirmed in vitro. 3'-NADP accumulated upon transient expression of AvrRxo1 in Nicotiana benthamiana and in rice leaves infected with avrRxo1-expressing strains of X. oryzae. Mutation of the catalytic aspartic acid residue D193 abolished AvrRxo1 kinase activity and several phenotypes of AvrRxo1, including toxicity in yeast, bacteria, and plants, suppression of the flg22-triggered ROS burst, and ability to trigger an R gene-mediated hypersensitive response. A mutation in the Walker A ATP-binding motif abolished the toxicity of AvrRxo1, but did not abolish the 3'-NADP production, virulence enhancement, ROS suppression, or HR-triggering phenotypes of AvrRxo1. These results demonstrate that a type III effector targets the central metabolite and redox carrier NAD in planta, and that this catalytic activity is required for toxicity and suppression of the ROS burst.
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Affiliation(s)
- Teja Shidore
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT, United States of America
| | - Corey D. Broeckling
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, CO, United States of America
| | - Jay S. Kirkwood
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, CO, United States of America
| | - John J. Long
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, United States of America
| | - Jiamin Miao
- Department of Horticulture, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States of America
| | - Bingyu Zhao
- Department of Horticulture, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States of America
| | - Jan E. Leach
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, United States of America
| | - Lindsay R. Triplett
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT, United States of America
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Schuebel F, Rocker A, Edelmann D, Schessner J, Brieke C, Meinhart A. 3'-NADP and 3'-NAADP, Two Metabolites Formed by the Bacterial Type III Effector AvrRxo1. J Biol Chem 2016; 291:22868-22880. [PMID: 27621317 PMCID: PMC5087710 DOI: 10.1074/jbc.m116.751297] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/01/2016] [Indexed: 12/12/2022] Open
Abstract
An arsenal of effector proteins is injected by bacterial pathogens into the host cell or its vicinity to increase virulence. The commonly used top-down approaches inferring the toxic mechanism of individual effector proteins from the host's phenotype are often impeded by multiple targets of different effectors as well as by their pleiotropic effects. Here we describe our bottom-up approach, showing that the bacterial type III effector AvrRxo1 of plant pathogens is an authentic phosphotransferase that produces two novel metabolites by phosphorylating nicotinamide/nicotinic acid adenine dinucleotide at the adenosine 3′-hydroxyl group. Both products of AvrRxo1, 3′-NADP and 3′-nicotinic acid adenine dinucleotide phosphate (3′-NAADP), are substantially different from the ubiquitous co-enzyme 2′-NADP and the calcium mobilizer 2′-NAADP. Interestingly, 3′-NADP and 3′-NAADP have previously been used as inhibitors or signaling molecules but were regarded as “artificial” compounds so far. Our findings now necessitate a shift in thinking about the biological importance of 3′-phosphorylated NAD derivatives.
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Affiliation(s)
- Felix Schuebel
- From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Andrea Rocker
- From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Daniel Edelmann
- From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Julia Schessner
- From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Clara Brieke
- From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Anton Meinhart
- From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
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Müller GL, Drincovich MF, Andreo CS, Lara MV. Nicotiana tabacum NADP-malic enzyme: cloning, characterization and analysis of biological role. PLANT & CELL PHYSIOLOGY 2008; 49:469-80. [PMID: 18272530 DOI: 10.1093/pcp/pcn022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
NADP-malic enzyme (NADP-ME) catalyzes the oxidative decarboxylation of L-malate, producing pyruvate, CO2 and NADPH. The photosynthetic role of this enzyme in C(4) and Crassulacean acid metabolism (CAM) plants has been well established; however, the biological role of several non-photosynthetic isoforms described in C(3), C(4) and CAM plants is still speculative. In this study, the characterization of the NADP-ME isoforms from Nicotiana tabacum was performed. Three different nadp-me transcripts were identified in this C(3) plant, two of which encode for putative cytosolic isoforms (DQ923118 and EH663836), while the third encodes for a plastidic counterpart (DQ923119). Although the three transcripts are expressed in vegetative as well as in reproductive tissues, they display different levels of expression. With regards to enzyme activity, root is the tissue that displays the highest NADP-ME activity. Recombinant NADP-MEs encoded by DQ923118 and DQ923119 were expressed in Escherichia coli and their kinetic parameters and response to different metabolic effectors were analyzed. Studies carried out with crude extracts and with the recombinant proteins indicate that the cytosolic and plastidic isoforms aggregate as tetramers of subunits of 65 and 63 kDa, respectively. Real-time reverse transcription-PCR studies show that the three nadp-me tobacco transcripts respond differently to several biotic and abiotic stress stimuli. Finally, the physiological role of each isoform is discussed in terms of the occurrence, kinetic properties and response to stress. The structure of the NADP-ME family in tobacco is compared with those of other C(3) species.
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Affiliation(s)
- Gabriela Leticia Müller
- Centro de Estudios Fotosintéticos y Bioquímicos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Suipacha 531, Rosario (2000), Argentina
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4
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Detarsio E, Andreo C, Drincovich M. Basic residues play key roles in catalysis and NADP(+)-specificity in maize (Zea mays L.) photosynthetic NADP(+)-dependent malic enzyme. Biochem J 2005; 382:1025-30. [PMID: 15245332 PMCID: PMC1133980 DOI: 10.1042/bj20040594] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2004] [Revised: 07/07/2004] [Accepted: 07/12/2004] [Indexed: 11/17/2022]
Abstract
C(4)-specific (photosynthetic) NADP(+)-dependent malic enzyme (NADP(+)-ME) has evolved from C(3)-malic enzymes and represents a unique and specialized form, as indicated by its particular kinetic and regulatory properties. In the present paper, we have characterized maize (Zea mays L.) photosynthetic NADP(+)-ME mutants in which conserved basic residues (lysine and arginine) were changed by site-directed mutagenesis. Kinetic characterization and oxaloacetate partition ratio of the NADP(+)-ME K255I (Lys-255-->Ile) mutant suggest that the mutated lysine residue is implicated in catalysis and substrate binding. Moreover, this residue could be acting as a base, accepting a proton in the malate oxidation step. At the same time, further characterization of the NADP(+)-ME R237L mutant indicates that Arg-237 is also a candidate for such role. These results suggest that both residues may play 'back-up' roles as proton acceptors. On the other hand, Lys-435 and/or Lys-436 are implicated in the coenzyme specificity (NADP(+) versus NAD(+)) of maize NADP(+)-ME by interacting with the 2'-phosphate group of the ribose ring. This is indicated by both the catalytic efficiency with NADP(+) or NAD(+), as well as by the reciprocal inhibition constants of the competitive inhibitors 2'-AMP and 5'-AMP, obtained when comparing the double mutant K435/6L (Lys-435/436-->Ile) with wild-type NADP(+)-ME. The results obtained in the present work indicate that the role of basic residues in maize photosynthetic NADP(+)-ME differs significantly with respect to its role in non-plant MEs, for which crystal structures have been resolved. Such differences are discussed on the basis of a predicted three-dimensional model of the enzyme.
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Affiliation(s)
- Enrique Detarsio
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Suipacha 531, Rosario, Sante Fe 2000, Argentina
| | - Carlos S. Andreo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Suipacha 531, Rosario, Sante Fe 2000, Argentina
- To whom correspondence should be addressed (email )
| | - María F. Drincovich
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Universidad Nacional de Rosario, Suipacha 531, Rosario, Sante Fe 2000, Argentina
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Spampinato CP, Andreo CS. Kinetic mechanism of NADP-malic enzyme from maize leaves. PHOTOSYNTHESIS RESEARCH 1995; 43:1-9. [PMID: 24306633 DOI: 10.1007/bf00029456] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/1994] [Accepted: 09/23/1994] [Indexed: 06/02/2023]
Abstract
The kinetic mechanism of NADP-dependent malic enzyme purified from maize leaves was studied in the physiological direction. Product inhibition and substrate analogues studies with 3' aminopyridine dinucleotide phosphate and tartrate indicate that the enzyme reaction follows a sequential ordered Bi-Ter kinetic mechanism. NADP is the leading substrate followed by L-malate and the products are released in the order of CO2, pyruvate and NADPH. The enzyme also catalyzes a slow, magnesium-dependent decarboxylation of oxaloacetate and reduction of pyruvate and oxaloacetate in the presence of NADPH to produce L-lactate and L-malate, respectively.
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Affiliation(s)
- C P Spampinato
- Centro de Estudios Fotosintéticos y Bioquímicos (CONICET, F.M. Lillo, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
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Spampinato CP, Colombo SL, Andreo CS. Interaction of analogues of substrate with NADP-malic enzyme from maize leaves. PHOTOSYNTHESIS RESEARCH 1994; 39:67-73. [PMID: 24311002 DOI: 10.1007/bf00027144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/1993] [Accepted: 10/14/1993] [Indexed: 06/02/2023]
Abstract
The effect of structural analogues of L-malate was studied on NADP-malic enzyme purified from Zea mays L. leaves. Among the compounds tested, the organic acids behaved as more potent inhibitors at pH 7.0 than at pH 8.0, suggesting that the dimeric form was more susceptible to the inhibition than the tetrameric form of the enzyme.Oxalate, ketomalonate, hydroxymalonate, malonate, oxaloacetate, tartrate, α-hydroxybutyrate, α-ketobutyrate, α-ketoglutarate and α-hydroxyglutarate exhibited linear competitive inhibition with respect to the substrate L-malate at pH 8.0. On the other hand, glyoxylate and glycolate turned out to be non-competitive inhibitors, while glycolaldehyde, succinate, fumarate, maleate and β- and γ-hydroxybutyrate had no effect on the enzyme activity, at the concentrations assayed. These results suggest that the extent of inhibition was dependent on the size of the analogues and that the presence of an 1-carboxyl group along with a 2-hydroxyl or 2-keto group was important for binding of the substrate analogue to the enzyme.
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Affiliation(s)
- C P Spampinato
- Centro de Estudios Fotosintéticos y Bioquímicos, (CONICET, F.M. Lillo, Universidad Nacional de Rosario), Suipacha 531, 2000, Rosario, Argentina
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