Bacterial catabolism of β-hydroxypropiovanillone and β-hydroxypropiosyringone produced in the reductive cleavage of arylglycerol-β-aryl ether in lignin
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Sphingobium sp. strain SYK-6 converts four stereoisomers of arylglycerol-β-guaiacyl ether into achiral β-hydroxypropiovanillone (HPV) via three stereospecific reaction steps. Here we determined the HPV catabolic pathway and characterized the HPV catabolic genes involved in the first two steps of the pathway. In SYK-6 cells, HPV was oxidized to vanilloyl acetic acid (VAA) via vanilloyl acetaldehyde (VAL). The resulting VAA was further converted into vanillate through the activation of VAA by coenzyme A. A syringyl-type HPV analog, β-hydroxypropiosyringone (HPS), was also catabolized via the same pathway. SLG_12830 (hpvZ), which belongs to the glucose-methanol-choline oxidoreductase family, was isolated as the HPV-converting enzyme gene. An hpvZ mutant completely lost the ability to convert HPV and HPS, indicating that hpvZ is essential for the conversion of both the substrates. HpvZ produced in Escherichia coli oxidized both HPV and HPS, and other 3-phenyl-1-propanol derivatives. HpvZ localized to both the cytoplasm and membrane of SYK-6 and used ubiquinone derivatives as electron acceptors. Thirteen gene products of the 23 aldehyde dehydrogenase (ALDH) genes in SYK-6 were able to oxidize VAL into VAA. Mutant analyses suggested that multiple ALDH genes, including SLG_20400, contribute to the conversion of VAL. We examined whether the genes encoding feruloyl-CoA synthetase (ferA) and feruloyl-CoA hydratase/lyase (ferB and ferB2) are involved in the conversion of VAA. Only FerA exhibited activity toward VAA; however, disruption of ferA did not affect VAA conversion. These results indicate that another enzyme system is involved in VAA conversion.
Higuchi , Y , Aoki , S , Takenami , H , Kamimura , N , Takahashi , K , Hishiyama , S , Lancefield , C S , Ojo , O S , Katayama , Y , Westwood , N J & Masai , E 2018 , ' Bacterial catabolism of β-hydroxypropiovanillone and β-hydroxypropiosyringone produced in the reductive cleavage of arylglycerol-β-aryl ether in lignin ' , Applied and Environmental Microbiology , vol. 84 , no. 7 , e02670-17 . https://doi.org/10.1128/AEM.02670-17
Applied and Environmental Microbiology
Copyright © 2018 American Society for Microbiology. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at: https://doi.org/10.1128/AEM.02670-17
DescriptionThis work was supported in part by a grant from the JSPS KAKENHI Grant Number 26850046, and the Japan Science and Technology Agency (Advanced Low Carbon Technology Research and Development Program).
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