tailieunhanh - Báo cáo khoa học: Final steps in the catabolism of nicotine Deamination versus demethylation of c-N-methylaminobutyrate

New enzymes of nicotine catabolism instrumental in the detoxification of the tobacco alkaloid by Arthrobacter nicotinovoranspAO1 have been iden-tified and characterized. Nicotine breakdown leads to the formation of nicotine blue from the hydroxylated pyridine ring and of c-N-methyl-aminobutyrate (CH3-4-aminobutyrate) from the pyrrolidine ring of the molecule. | iFEBS Journal Final steps in the catabolism of nicotine Deamination versus demethylation of y-W-methylaminobutyrate Calin-Bogdan Chiribau1 Marius Mihasan1 2 Petra Ganas1 Gabor L. Igloi3 Vlad Artenie2 and Roderich Brandsch1 1 Institute of Biochemistry and Molecular Biology Alberts-Ludwig University of Freiburg Germany 2 Department of Biochemistry Alexandru Ioan-Cuza University of Iasi Romania 3 Institute of Biology III Alberts-Ludwig University of Freiburg Germany Keywords amine oxidase Arthrobacter nicotinovorans nicotine y-N-methylaminobutyrate succinic semialdehyde dehydrogenase Correspondence R. Brandsch Institut fur Biochemie und Molekularbiologie Hermann-Herder-Str. 7 D-79104 Freiburg Germany Fax 41 761 2035253 Tel 41 761 2035231 E-mail . Received 23 November 2005 revised 1 February 2006 accepted 10 February 2006 doi New enzymes of nicotine catabolism instrumental in the detoxification of the tobacco alkaloid by Arthrobacter nicotinovorans pAO1 have been identified and characterized. Nicotine breakdown leads to the formation of nicotine blue from the hydroxylated pyridine ring and of y-N-methyl-aminobutyrate CH3-4-aminobutyrate from the pyrrolidine ring of the molecule. Surprisingly two alternative pathways for the final steps in the catabolism of CH3-4-aminobutyrate could be identified. CH3-4-aminobuty-rate may be demethylated to y-N-aminobutyrate by the recently identified y-N-methylaminobutyrate oxidase Chiribau et al. 2004 Eur J Biochem 271 4677-4684 . In an alternative pathway an amine oxidase with noncov-alently bound FAD and of novel substrate specificity removed methylamine from CH3-4-aminobutyrate with the formation of succinic semialdehyde. Succinic semialdehyde was converted to succinate by a NADP -dependent succinic semialdehyde dehydrogenase. Succinate may enter the citric acid cycle completing the catabolism of the pyrrolidine moiety of nicotine. Expression of the genes .