Dataset Information

Cloning and characterization of enoate reductase with high ?-ionone to dihydro-?-ionone bioconversion productivity.

ABSTRACT: BACKGROUND:Dihydro-?-ionone is a principal aroma compound and has received considerable attention by flavor and fragrance industry. The traditional method of preparing dihydro-?-ionone has many drawbacks, which has restricted its industrial application. Therefore, it is necessary to find a biotechnological method to produce dihydro-?-ionone. RESULTS:In this study, the enoate reductase with high conversion efficiency of ?-ionone to dihydro-?-ionone, DBR1, was obtained by screening four genetically engineered bacteria. The product, dihydro-?-ionone, was analyzed by GC and GC-MS. The highest dihydro-?-ionone production with 308.3 mg/L was detected in the recombinant strain expressing DBR1 which was later on expressed and purified. Its optimal temperature and pH were 45 °C and 6.5, respectively. The greatest activity of the purified enzyme was 356.39 U/mg using ?-ionone as substrate. In the enzymatic conversion system, 1 mM of ?-ionone was transformed into 91.08 mg/L of dihydro-?-ionone with 93.80% of molar conversion. CONCLUSION:DBR1 had high selectivity to hydrogenated the 10,11-unsaturated double bond of ?-ionone as well as high catalytic efficiency for the conversion of ?-ionone to dihydro-?-ionone. It is the first report on the bioconversion of ?-ionone to dihydro-?-ionone by using enoate reductase.

SUBMITTER: Zhang X

PROVIDER: S-EPMC5944158 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Cloning and characterization of enoate reductase with high β-ionone to dihydro-β-ionone bioconversion productivity.

Zhang Xuesong X Liao Shiyong S Cao Fuliang F Zhao Linguo L Pei Jianjun J Tang Feng F

BMC biotechnology 20180509 1

<h4>Background</h4>Dihydro-β-ionone is a principal aroma compound and has received considerable attention by flavor and fragrance industry. The traditional method of preparing dihydro-β-ionone has many drawbacks, which has restricted its industrial application. Therefore, it is necessary to find a biotechnological method to produce dihydro-β-ionone.<h4>Results</h4>In this study, the enoate reductase with high conversion efficiency of β-ionone to dihydro-β-ionone, DBR1, was obtained by screening ...[more]

PMID: 29743047

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Project description:BackgroundBrown macroalgae dominate temperate coastal ecosystems, and their productivity is typically limited by nitrate availability. As an economically important kelp, Saccharina japonica is the most productive farmed seaweed and needs to be supplemented with sufficient nitrate throughout the cultivation process. However, molecular characterization of genes involved in nitrogen assimilation has not been conducted in brown macroalgae.ResultsHere, we described the identification of the nitrate reductase (NR) gene from S. japonica (SjNR). Using two different cloning methods for SjNR, i.e. rapid amplification of cDNA ends (RACE) and cDNA cloning alone, a single fragment was obtained respectively. According to results of sequence analysis between these two fragments, the tentative coding sequence in two clones, SjNR-L and SjNR-S, were suggested to represent two transcripts of the single copy SjNR, and the ATG of SjNR-S was located inside the third exon of SjNR-L. In the 5' upstream sequence of each transcript, promoter core elements, response elements, especially multiple N response elements which occurred in microalgal NR, were all predicted. Further sequence analysis revealed that both transcripts encoded all five domains conserved in eukaryotic plant NRs. RT-qPCR results showed that the transcription level of SjNR in juvenile sporophytes could be significantly induced by nitrate and inhibited by ammonium, which was in line with plant NRs. The recombinant SjNR-L and SjNR-S were all proved to have NR activity, suggesting that the single-copy gene SjNR might be regulated on transcription level based on alternative promoters and multiple transcriptional start sites. Moreover, both NADH and NADPH were found to be able to act as electron donors for SjNR alone, which is the first confirmation that brown algal NR has a NAD(P)H-bispecific form.ConclusionThese results will provide a scientific basis for understanding the N demand of kelp in various stages of cultivation and evaluating the environmental remediation potential of kelp in eutrophic sea areas.

Project description:BackgroundErythrose reductase (ER) catalyzes the final step of erythritol production, which is reducing erythrose to erythritol using NAD(P)H as a cofactor. ER has gained interest because of its importance in the production of erythritol, which has extremely low digestibility and approved safety for diabetics. Although ERs were purified and characterized from microbial sources, the entire primary structure and the corresponding DNA for ER still remain unknown in most of erythritol-producing yeasts. Candida magnoliae JH110 isolated from honeycombs produces a significant amount of erythritol, suggesting the presence of erythrose metabolizing enzymes. Here we provide the genetic sequence and functional characteristics of a novel NADPH-dependent ER from C. magnoliae JH110.ResultsThe gene encoding a novel ER was isolated from an osmophilic yeast C. magnoliae JH110. The ER gene composed of 849 nucleotides encodes a polypeptide with a calculated molecular mass of 31.4 kDa. The deduced amino acid sequence of ER showed a high degree of similarity to other members of the aldo-keto reductase superfamily including three ER isozymes from Trichosporonoides megachiliensis SNG-42. The intact coding region of ER from C. magnoliae JH110 was cloned, functionally expressed in Escherichia coli using a combined approach of gene fusion and molecular chaperone co-expression, and subsequently purified to homogeneity. The enzyme displayed a temperature and pH optimum at 42 degrees C and 5.5, respectively. Among various aldoses, the C. magnoliae JH110 ER showed high specific activity for reduction of erythrose to the corresponding alcohol, erythritol. To explore the molecular basis of the catalysis of erythrose reduction with NADPH, homology structural modeling was performed. The result suggested that NADPH binding partners are completely conserved in the C. magnoliae JH110 ER. Furthermore, NADPH interacts with the side chains Lys252, Thr255, and Arg258, which could account for the enzyme's absolute requirement of NADPH over NADH.ConclusionsA novel ER enzyme and its corresponding gene were isolated from C. magnoliae JH110. The C. magnoliae JH110 ER with high activity and catalytic efficiency would be very useful for in vitro erythritol production and could be applied for the production of erythritol in other microorganisms, which do not produce erythritol.

Dataset Information

Cloning and characterization of enoate reductase with high ?-ionone to dihydro-?-ionone bioconversion productivity.

Publications

Cloning and characterization of enoate reductase with high β-ionone to dihydro-β-ionone bioconversion productivity.

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