Oxidation of both termini of p- and m-xylene by Escherichia coli transformed with xylene monooxygenase gene |
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Authors: | Takahiro Maruyama Hiroshi Iida Hitoshi Kakidani |
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Institution: | Tokyo Research Center, Tosoh Corporation, Ayase, Kanagawa 252-1123, Japan |
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Abstract: | Xylene monooxygenase (XMO) from Pseudomonas putida mt-2 catalyzes oxidation of methyl group of toluene and xylenes. While it has been postulated that this enzyme oxidizes one methyl group of xylene, we observed that both methyl groups in p- and m-xylene were oxidized to alcohol and aldehyde when the relevant genes (xylM and xylA) were co-expressed in Escherichia coli C600 and MC4100. When p-xylene was used as a substrate, p-hydroxymethylbenzaldehyde and p-xylyleneglycol were identified, in addition to p-methylbenzylalcohol and p-tolualdehyde. When m-xylene was used as a substrate, m-hydroxymethylbenzaldehyde and m-xylyleneglycol were identified, in addition to m-methylbenzylalcohol and m-tolualdehyde. Ratio of the products varied significantly according to the reaction condition and host strain, presumably reflecting the relative activity of XMO and host-derived dehydrogenase(s). Using various oxidized compounds as substrates, it was indicated that dialcohol (p- or m-xylyleneglycol) was formed via p- or m-hydroxymethylbenzaldehyde, respectively, rather than directly from corresponding monoalcohol (p- or m-methybenzylalcohol). |
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Keywords: | Xylene monooxygenase Pseudomonas putida Xylene Xylyleneglycol Hydroxymethylbenzaldehyde |
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