Discovery of piperonal-converting oxidase involved in the metabolism of a botanical aromatic aldehyde.

Shiori Doi,Takuto Kumano,Michihiko Kobayashi,Chiaki Tomita,Yoshiteru Hashimoto

doi:10.1038/srep38021

Shiori Doi, Takuto Kumano + Show 3 more

Open Access

https://doi.org/10.1038/srep38021

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Abstract

Piperonal-catabolizing microorganisms were isolated from soil, the one (strain CT39-3) exhibiting the highest activity being identified as Burkholderia sp. The piperonal-converting enzyme involved in the initial step of piperonal metabolism was purified from strain CT39-3. Gene cloning of the enzyme and a homology search revealed that the enzyme belongs to the xanthine oxidase family, which comprises molybdoenzymes containing a molybdopterin cytosine dinucleotide cofactor. We found that the piperonal-converting enzyme acts on piperonal in the presence of O2, leading to formation of piperonylic acid and H2O2. The growth of strain CT39-3 was inhibited by higher concentrations of piperonal in the culture medium. Together with this finding, the broad substrate specificity of this enzyme for various aldehydes suggests that it would play an important role in the defense mechanism against antimicrobial compounds derived from plant species.

Highlights

The 16 S rRNA gene sequence of the isolated microorganism was used as a query to search for homologous sequences in the Ribosomal Database Project (RDP)[4]
There is an enormously diverse range of specific secondary metabolites depending on the species or group
Degradation of various kinds of secondary metabolites produced by higher plants has been reported

Summary

Introduction

Cell-free extracts prepared from the strain CT39-3 transformant carrying pBBR-His-pceSML, which was cultured at 28 °C, rapidly converted piperonal (as a substrate) into piperonylic acid. The piperonal-converting enzyme produced in the recombinant cells was purified to homogeneity through the HisTrap HP column chromatography described under “SI Methods”. The results demonstrated that piperonylic acid and H2O2 were formed stoichiometrically with the consumption of piperonal and O2 during the enzyme reaction, and that O2 acted as a terminal electron acceptor.

Results

Conclusion