tailieunhanh - Báo cáo khoa học: Role of Acinetobacter calcoaceticus 3,4-dihydrocoumarin hydrolase in oxidative stress defence against peroxoacids Kohsuke Honda, Michihiko Kataoka, Eiji Sakuradani and Sakayu Shimizu

The physiological role of a bifunctional enzyme, 3,4-dihydrocoumarin hydrolase (DCH), which is capable of both hydrolysis of ester bonds and organic acid-assisted bromination of organic compounds, was investigated. Purified DCH fromAcinetobacter calcoaceticusF46 cata-lysed dose- and time-dependent degradation of peracetic acid. The gene (dch) was cloned from the chromosomal DNA of the bacterium. | Eur. J. Biochem. 270 486-494 2003 FEBS 2003 doi Role of Acinetobacter calcoaceticus 3 4-dihydrocoumarin hydrolase in oxidative stress defence against peroxoacids Kohsuke Honda Michihiko Kataoka Eiji Sakuradani and Sakayu Shimizu Division of Applied Life Sciences Graduate School of Agriculture Kyoto University Japan The physiological role of a bifunctional enzyme 3 4-dihydrocoumarin hydrolase DCH which is capable of both hydrolysis of ester bonds and organic acid-assisted bromination of organic compounds was investigated. Purified DCH from Acinetobacter calcoaceticus F46 catalysed dose- and time-dependent degradation of peracetic acid. The gene dch was cloned from the chromosomal DNA of the bacterium. The dch ORF was 831 bp long corresponding to a protein of 272 amino acid residues and the deduced amino acid sequence showed high similarity to those of bacterial serine esterases and perhydrolases. The dch gene was disrupted by homologous recombination on the A. calcoaceticus genome. The dch disruptant strain was more sensitive to growth inhibition by peracetic acid than the parent strain. On the other hand the recombinant Escherichia coli cells expressing dch were more resistant to peracetic acid. A putative catalase gene was found immediately downstream of dch and Northern blot hybridization analysis revealed that they are transcribed as part of a polycistronic mRNA. These results suggested that in vivo DCH detoxifies peroxoacids in conjunction with the catalase . peroxoacids are first hydrolysed to the corresponding acids and hydrogen peroxide by DCH and then the resulting hydrogen peroxide is degraded by the catalase. Keywords Acinetobacter calcoaceticus catalase 3 4-dihydro-coumarin hydrolase perhydrolase peroxoacid. In a previous study we found and isolated a novel lactonohydrolase 3 4-dihydrocoumarin hydrolase DCH from Acinetobacter calcoaceticus F46 1 . The amino acid sequences of the N-terminal and internal peptide of DCH .