Identification, Cloning, and Functional Characterization of Carotenoid Cleavage Dioxygenase (CCD) from <i>Olea europaea</i> and <i>Ipomoea nil</i>
The aromatic C<sub>13</sub> apocarotenoid β-ionone is a high-value natural-flavor and -fragrance compound derived from the oxidative cleavage of carotenoids. Carotenoid cleavage dioxygenases (CCDs) play a pivotal role in the biosynthesis of volatile apocarotenoids, particularly β-ionone....
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Biology |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2079-7737/14/7/752 |
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| Summary: | The aromatic C<sub>13</sub> apocarotenoid β-ionone is a high-value natural-flavor and -fragrance compound derived from the oxidative cleavage of carotenoids. Carotenoid cleavage dioxygenases (CCDs) play a pivotal role in the biosynthesis of volatile apocarotenoids, particularly β-ionone. In this study, we report the identification, cloning, and functional characterization of two CCD1 homologs: <i>OeCCD1</i> from <i>Olea europaea</i> and <i>InCCD1</i> from <i>Ipomoea nil</i>. These two species, which, respectively, represent a woody perennial and a herbaceous annual, were selected to explore the potential functional divergence of CCD1 enzymes across different plant growth forms. These CCD1 genes were synthesized using codon optimization for <i>Escherichia coli</i> expression, followed by heterologous expression and purification using a GST-fusion system. In vitro assays confirmed that both enzymes cleave β-carotene at the 9,10 (9′,10′) double bond to yield β-ionone, but only <i>OeCCD1</i> exhibits detectable activity on zeaxanthin; <i>InCCD1</i> shows no in vitro cleavage of zeaxanthin. Kinetic characterization using β-apo-8′-carotenal as substrate revealed, for <i>OeCCD1</i>, a K<sub>m</sub> of 0.82 mM, V<sub>max</sub> of 2.30 U/mg (k<sub>cat</sub> = 3.35 s<sup>−1</sup>), and k<sub>cat</sub>/K<sub>m</sub> of 4.09 mM<sup>−1</sup>·s<sup>−1</sup>, whereas <i>InCCD1</i> displayed K<sub>m</sub> = 0.69 mM, V<sub>max</sub> = 1.22 U/mg (k<sub>cat</sub> = 1.82 s<sup>−1</sup>), and k<sub>cat</sub>/K<sub>m</sub> = 2.64 mM<sup>−1</sup>·s<sup>−1</sup>. The optimization of expression parameters, as well as the systematic evaluation of temperature, pH, solvent, and metal ion effects, provided further insights into the stability and functional diversity within the plant CCD1 family. Overall, these findings offer promising enzymatic tools for the sustainable production of β-ionone and related apocarotenoids in engineered microbial cell factories. |
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| ISSN: | 2079-7737 |