12-oxophytodienoate reductase

Structure of 12-oxophytodienoate reductase (OPR3) bound to FMN cofactor, created in Pymol.[1]
12-oxophytodienoate reductase
Identifiers
EC number 1.3.1.42
CAS number 101150-03-2
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO

12-oxophytodienoate reductase (OPRs) is an enzyme of the family of Old Yellow Enzymes (OYE). [2] OPRs are grouped into two groups: OPRI and OPRII – the second group is the focus of this article, as the function of the first group is unknown, but is the subject of current research. [3] The OPR enzyme utilizes the cofactor flavin mononucleotide (FMN) and catalyzses the following reaction in the jasmonic acid synthesis pathway: [4]

Reaction catalyzed by 12-oxophytodienoate reductase in the jasmonic acid synthesis pathway.[1]

This reaction occurs in peroxisomes in plants. [5] Several isozymes have been discovered, with varying substrate stereospecificity: three in Lycopersicon escultentum, 13 in Oryza sativa, and five in Arabidopsis thaliana. [6] The OPR3 isozyme is most extensively studied because it can reduce all 4 stereoisomers of the substrate, OPDA and because it has shown to be the most significant enzyme in the jasmonic acid synthesis pathway. [7][4]

Structure

12-oxophytodienoate reductase structure resembles OYE enzymes and has been elucidated by x-ray crystal structures. [1] The cDNA encodes 372 amino acids for this enzyme. [2] It exhibits a barrel fold of eight parallel beta-strands surrounded by eight alpha-helices to create a barrel shape. [6] Turns at the N-terminus loops of the beta-strands have been shown to contain three to four amino acid residues and the C-terminus loops range between three to 47 amino acid residues. [6] The C-terminus loops largely make up the active site and the larger range of the amount of residues is due to the diversity in the different isozyme active sites. [6]

OPR3, the most extensively studied isoform of 12-oxophytodienoate reductase, has a wider binding pocket than OPR1, which is enantioselective for only one OPDA substrate enantiomer. [1] The residues Tyr78 and Tyr246 that are at the mouth of the active site are responsible for the higher enantioselectivity of OPR1. [8] [1] OPR1 and OPR3 have identical substrate binding residues, but the difference in the width of the mouth of the active site determines the OPR1 specificity. [8][1]

12-oxophytodienoate reductase isomers OPR3 (blue) and OPR1 (green) with FMN cofactor (pink).[1]

12-oxophytodienoate reductase has also been shown to practice self-inhibition by dimerization. [6] This is the only flavoprotein known to dimerize for inhibition and this dimerization is thought to be regulated by phosphorylation. [6] The dimerization occurs by the mutual binding of two loops into the two active sites. [6] These loops are highly evolutionarily conserved, indicating the dimerization is purposeful and significant in regulation. [6]

12-oxophytodienoate reductase (OPR3) dimerized to itself. This dimer provides self-inhibition of the enzyme.[1]

Mechanism

The reduction mechanism employed has been shown to be a ping-pong, bi-bi mechanism. [6] The FMN cofactor is first reduced by NADPH, the substrate is then bound, and finally the substrate is reduced by a hydride transfer from NADPH to the substrate’s beta carbon. [6] The Km of OPR3 in Zea Mays was found to be 190 micromolar for its substrate OPDA. [9]

Biological Function

The reaction catalyzed by 12-oxophytodienoate reductase is in the jasmonic acid biosynthesis pathway. Jasmonic acid is known for its importance as a gene regulator for development and defense. [4] [10] [11] [12]

OPR3 is shown to be induced by touch, wind, UV light, application of detergent, wounding, and brassinosteroids. [4] In wound response, its activity has been shown to partially depend on jasmonic acid perception. [4] It is also shown to have greater enzyme efficiency than OPR1 and OPR2 in Arabidopsis Thaliana, showing it is the significant enzyme in the jasmonic acid biosynthesis pathway. [4]

Relevance to Agriculture

This enzyme is of interest in plant biology research because the disrupted OPR3 gene has been shown to cause male sterility in Arabidopsis Thaliana. [13] This is a point of interest in understanding the factors surrounding viable pollen development, a focus of research in the agriculture industry. [13]

Relevance to Phytoremediation

OPR has shown to also function in the reduction of explosive 2,4,6-trinitrotoluene (TNT). [14] Because TNT is a known toxic, environmental pollutant that is difficult to degrade, the use of phytoremediation to clean up sites contaminated with TNT is of significant interest. [14] OPR1 degraded TNT faster and with greater amount of degraded products than other isozymes. [14] This enzyme could therefore be used in phytoremediation. [14]

Phylogenetics

A phylogenetic analysis studying the structural evolution and functional divergence of the various OPR paralogues found seven conserved sub-families and suggested expansion of the OPR families occurred in land plants. [15] A total of 74 OPR genes in 11 species from six major plant lineages were found. [15] Surprisingly, introns were found to differ in length and number, but conserved in position, indicating successive intron loss. [15] The study also indicated that the substrate binding loop and the alpha-helices, but not the beta-sheets, were critical for functional divergence after sub-families were established and are therefore important in the OPR proteins. [15]

References

  1. 1 2 3 4 5 6 7 8 Breithaupt C, Strassner J, Breitinger U, Huber R, Macheroux P, Schaller A; et al. (2001). "X-ray structure of 12-oxophytodienoate reductase 1 provides structural insight into substrate binding and specificity within the family of OYE.". Structure 9 (5): 419–29. doi:10.1016/s0969-2126(01)00602-5. PMID 11377202.
  2. 1 2 Schaller F, Weiler EW (1997). "Molecular cloning and characterization of 12-oxophytodienoate reductase, an enzyme of the octadecanoid signaling pathway from Arabidopsis thaliana. Structural and functional relationship to yeast old yellow enzyme.". J Biol Chem 272 (44): 28066–72. doi:10.1074/jbc.272.44.28066. PMID 9346960.
  3. ↑ Dong W, Wang M, Xu F, Quan T, Peng K, Xiao L; et al. (2013). "Wheat oxophytodienoate reductase gene TaOPR1 confers salinity tolerance via enhancement of abscisic acid signaling and reactive oxygen species scavenging.". Plant Physiol 161 (3): 1217–28. doi:10.1104/pp.112.211854. PMC 3585591. PMID 23321418.
  4. 1 2 3 4 5 6 Schaller F, Biesgen C, Müssig C, Altmann T, Weiler EW (2000). "12-Oxophytodienoate reductase 3 (OPR3) is the isoenzyme involved in jasmonate biosynthesis.". Planta 210 (6): 979–84. doi:10.1007/s004250050706. PMID 10872231.
  5. ↑ Strassner J, Schaller F, Frick UB, Howe GA, Weiler EW, Amrhein N; et al. (2002). "Characterization and cDNA-microarray expression analysis of 12-oxophytodienoate reductases reveals differential roles for octadecanoid biosynthesis in the local versus the systemic wound response.". Plant J 32 (4): 585–601. doi:10.1046/j.1365-313x.2002.01449.x. PMID 12445129.
  6. 1 2 3 4 5 6 7 8 9 10 Breithaupt C, Kurzbauer R, Lilie H, Schaller A, Strassner J, Huber R; et al. (2006). "Crystal structure of 12-oxophytodienoate reductase 3 from tomato: self-inhibition by dimerization.". Proc Natl Acad Sci U S A 103 (39): 14337–42. doi:10.1073/pnas.0606603103. PMC 1586121. PMID 16983071.
  7. ↑ Schaller F, Hennig P, Weiler EW (1998). "12-Oxophytodienoate-10,11-reductase: occurrence of two isoenzymes of different specificity against stereoisomers of 12-oxophytodienoic acid". Plant Physiol 118 (4): 1345–51. doi:10.1104/pp.118.4.1345. PMC 34750. PMID 9847108.
  8. 1 2 Breithaupt C, Kurzbauer R, Schaller F, Stintzi A, Schaller A, Huber R; et al. (2009). "Structural basis of substrate specificity of plant 12-oxophytodienoate reductases.". J Mol Biol 392 (5): 1266–77. doi:10.1016/j.jmb.2009.07.087. PMID 19660473.
  9. ↑ Vick BA, Zimmerman DC (1986). "Characterization of 12-oxo-phytodienoic Acid reductase in corn: the jasmonic Acid pathway.". Plant Physiol 80 (1): 202–5. doi:10.1104/pp.80.1.202. PMC 1075082. PMID 16664582.
  10. ↑ Engelberth J, Seidl-Adams I, Schultz JC, Tumlinson JH (2007). "Insect elicitors and exposure to green leafy volatiles differentially upregulate major octadecanoids and transcripts of 12-oxo phytodienoic acid reductases in Zea mays.". Mol Plant Microbe Interact 20 (6): 707–16. doi:10.1094/MPMI-20-6-0707. PMID 17555278.
  11. ↑ Costa CL, Arruda P, Benedetti CE (2000). "An Arabidopsis gene induced by wounding functionally homologous to flavoprotein oxidoreductases.". Plant Mol Biol 44 (1): 61–71. PMID 11094980.
  12. ↑ Tani T, Sobajima H, Okada K, Chujo T, Arimura S, Tsutsumi N; et al. (2008). "Identification of the OsOPR7 gene encoding 12-oxophytodienoate reductase involved in the biosynthesis of jasmonic acid in rice.". Planta 227 (3): 517–26. doi:10.1007/s00425-007-0635-7. PMID 17938955.
  13. 1 2 Stintzi A, Browse J (2000). "The Arabidopsis male-sterile mutant, opr3, lacks the 12-oxophytodienoic acid reductase required for jasmonate synthesis.". Proc Natl Acad Sci U S A 97 (19): 10625–30. doi:10.1073/pnas.190264497. PMC 27075. PMID 10973494.
  14. 1 2 3 4 Beynon ER, Symons ZC, Jackson RG, Lorenz A, Rylott EL, Bruce NC (2009). "The role of oxophytodienoate reductases in the detoxification of the explosive 2,4,6-trinitrotoluene by Arabidopsis.". Plant Physiol 151 (1): 253–61. doi:10.1104/pp.109.141598. PMC 2735992. PMID 19605548.
  15. 1 2 3 4 Li W, Liu B, Yu L, Feng D, Wang H, Wang J (2009). "Phylogenetic analysis, structural evolution and functional divergence of the 12-oxo-phytodienoate acid reductase gene family in plants.". BMC Evol Biol 9: 90. doi:10.1186/1471-2148-9-90. PMC 2688005. PMID 19416520.
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