Fatty acid 9‐ and 13‐hydroperoxide lyases from cucumber<sup>1</sup>

Matsui, Kenji; Ujita, Chika; Fujimoto, Sho-hei; Wilkinson, Jack; Hiatt, Bill; Knauf, Vic; Kajiwara, Tadahiko; Feußner, Ivo

doi:10.1016/s0014-5793(00)01997-9

Cited by 107 publications

(100 citation statements)

References 24 publications

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“…Second, in contrast to the specificity of most AOSs for 13-hydroperoxides, LeAOS3 exhibits a marked preference for 9-hydroperoxides. A similar substrate preference was reported for the two cucurbit HPLs that are the closest known relatives of LeAOS3 (33,34). This observation suggests that the sequence relatedness between various CYP74 P-450s is an indicator of substrate specificity.…”

Section: Table II Substrate Specificity Of Recombinant Leaos3supporting

confidence: 78%

“…LeAOS3 was most active against 9-HPOD, as determined both by the estimated turnover rate (k cat ) and catalytic efficiency (k cat /K m ). The estimated k cat value (820 s Ϫ1 ) for 9-HPOD was comparable to turnover rates reported for other recombinant CYP74 enzymes (4,23,33,34).…”

Section: Figsupporting

confidence: 78%

“…13-HPLs). CYP74C P450s from cucumber (CsHPL) and melon (CmHPL) are HPLs that have a preference, but not absolute specificity, for 9-hydroperoxides (33,34). Members of the CYP74D subfamily are DESs that have high specificity for 9-hydroperoxides (23,35).…”

Section: Identification Of a New Member Of The Cyp74 Gene Family Inmentioning

confidence: 99%

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Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Itoh¹,

Schilmiller

McCaig³

et al. 2002

Journal of Biological Chemistry

105

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Allene oxide synthase (AOS) is a cytochrome P-450 (CYP74A) that catalyzes the first step in the conversion of 13-hydroperoxy linolenic acid to jasmonic acid and related signaling molecules in plants. Here, we report the molecular cloning and characterization of a novel AOS-encoding cDNA (LeAOS3) from Lycopersicon esculentum whose predicted amino acid sequence classifies it as a member of the CYP74C subfamily of enzymes that was hitherto not known to include AOSs. Recombinant LeAOS3 expressed in Escherichia coli showed spectral characteristics of a P-450. The enzyme transformed 9-and 13-hydroperoxides of linoleic and linolenic acid to ␣-ketol, ␥-ketol, and cyclopentenone compounds that arise from spontaneous hydrolysis of unstable allene oxides, indicating that the enzyme is an AOS. Kinetic assays demonstrated that LeAOS3 was Ϸ10-fold more active against 9-hydroperoxides than the corresponding 13-isomers. LeAOS3 transcripts accumulated in roots, but were undetectable in aerial parts of mature plants. In contrast to wild-type plants, LeAOS3 expression was undetectable in roots of a tomato mutant that is defective in jasmonic acid signaling. These findings suggest that LeAOS3 plays a role in the metabolism of 9-lipoxygenase-derived hydroperoxides in roots, and that this branch of oxylipin biosynthesis is regulated by the jasmonate signaling cascade.Oxylipins comprise a group of biologically active compounds that are produced by oxidative metabolism of polyunsaturated fatty acids. Members of the eicosanoid family of lipid mediators have been studied extensively with respect to their biosynthesis from arachidonic acid and their function in diverse physiological processes in animal cells (1). In plants, which lack arachidonic acid, oxygenated derivatives of C 18 fatty acids participate in the regulation of many defense-related and developmental processes. The biosynthesis of most phytooxylipins is initiated by lipoxygenase (LOX), 1 which adds molecular oxygen to either the C-9 or C-13 position of linolenic or linoleic acid (2). The resulting hydroperoxides are further metabolized by several enzymes including three closely related members of the CYP74 family of cytochromes P-450: allene oxide synthase (AOS), hydroperoxide lyase (HPL), and divinyl ether synthase (DES). Indeed, much of the structural and functional diversity in oxylipin metabolism in plants can be accounted for by the activity of CYP74s that metabolize 9-and 13-hydroperoxides to a wide range of products (3). In contrast to typical P-450 monooxygenases, CYP74 P-450s do not require O 2 and a NADPHdependent P-450 reductase for activity. Rather, they use a hydroperoxide group both as the oxygen donor and as a source of reducing equivalents (4, 5). This unique catalytic feature is shared by thromboxane synthase and prostacyclin synthase, two P-450 enzymes involved in the synthesis of eicosanoids (6). A greater understanding of the biochemical and physiological function of this atypical class of P-450 enzymes promises to provide new insight into the evolution ...

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Section: Table II Substrate Specificity Of Recombinant Leaos3supporting

confidence: 78%

Section: Figsupporting

confidence: 78%

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Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Itoh¹,

Schilmiller

McCaig³

et al. 2002

Journal of Biological Chemistry

105

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“…While the 13-HPLs belong to the CYP74B subfamily, they are members of the CYP74C subfamily and have got the highest sequence similarity to AOS enzymes . The 9/13-HPL from cucumber shows the highest activity towards 9-HPODE (Matsui et al, 2000), whereas the HPL from melon prefers 9-HPOTE (Tijet et al, 2000). The activity against the other hydroperoxides ranged from 80 % to 22 %.…”

Section: Discussionmentioning

confidence: 99%

“…This system is always created by LOXs after metabolizing a (1Z,4Z)-diene system. Additional double bounds influence the activity rate: in case of 13-HPLs a double bound at the other site of the hydroperoxide group leads to an increase in activity Howe and Schilmiller, 2002) whereas in case of CsHPL (Matsui et al, 2000) and PpHPL the activity decreased. Analyses of the specificity of the tea leave HPL, a 13-HPL, and our results indicated that the absolute position of the diene system in relation to the methylene end and not to the carboxyl end is an important factor for the substrate specificity.…”

Section: Discussionmentioning

confidence: 99%

Lipid metabolism in arbuscular mycorrhizal roots of Medicago truncatula

Stumpe¹,

Carsjens²,

Stenzel

et al. 2005

Phytochemistry

Self Cite

117

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Fatty Acid Hydroperoxide Lyase: A Plant Cytochrome P450 Enzyme Involved in Wound Healing and Pest Resistance

2001

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Plants continuously have to defend themselves against life-threatening events such as drought, mechanical damage, temperature stress, and potential pathogens. Nowadays, more and more similarities between the defense mechanism of plants and that of animals are being discovered. In both cases, the lipoxygenase pathway plays an important role. In plants, products of this pathway are involved in wound healing, pest resistance, and signaling, or they have antimicrobial and antifungal activity. The first step in the lipoxygenase pathway is the reaction of linoleic or linolenic acids with molecular oxygen, catalyzed by the enzyme lipoxygenase. The hydroperoxy fatty acids thus formed are highly reactive and dangerous for the plant and therefore further metabolized by other enzymes such as allene oxide synthase, hydroperoxide lyase, peroxygenase, or divinyl ether synthase. Recently, these enzymes have been characterized as a special class of cytochrome P450 enzymes. Hydroperoxide lyases cleave the lipoxygenase products, resulting in the formation of omega-oxo acids and volatile C6- and C9-aldehydes and -alcohols. These compounds are major contributors to the characteristic "fresh green" odor of fruit and vegetables. They are widely used as food flavors, for example, to restore the freshness of food after sterilization processes. The low abundance of these compounds in nature and the high demand make it necessary to synthesize them on a large scale. Lipoxygenase and hydroperoxide lyase are suitable biocatalysts for the production of "natural" food flavors. In contrast to lipoxygenase, which has been extensively studied, little is yet known about hydroperoxide lyase. Hydroperoxide lyases from different organisms have been isolated, and a few genes have been published lately. However, the structure and reaction mechanism of this enzyme are still unclear. The identification of this enzyme as a cytochrome P450 sheds new light on its structure and possible reaction mechanism, whereas recombinant expression brings a biocatalytic application into sight.

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Fatty acid 9‐ and 13‐hydroperoxide lyases from cucumber¹

Cited by 107 publications

References 24 publications

Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Lipid metabolism in arbuscular mycorrhizal roots of Medicago truncatula

Fatty Acid Hydroperoxide Lyase: A Plant Cytochrome P450 Enzyme Involved in Wound Healing and Pest Resistance

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Fatty acid 9‐ and 13‐hydroperoxide lyases from cucumber1

Cited by 107 publications

References 24 publications

Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids

Lipid metabolism in arbuscular mycorrhizal roots of Medicago truncatula

Fatty Acid Hydroperoxide Lyase: A Plant Cytochrome P450 Enzyme Involved in Wound Healing and Pest Resistance

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Fatty acid 9‐ and 13‐hydroperoxide lyases from cucumber¹