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Plant Cell Physiol. 2007 Mar;48(3):550-4. Epub 2007 Feb 5.

Molecular cloning of N-methylputrescine oxidase from tobacco.

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Nara Institute of Science and Technology, Graduate School of Biological Sciences, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan.


Nicotine biosynthesis in Nicotiana species requires an oxidative deamination of N-methylputrescine, catalyzed by N-methylputrescine oxidase (MPO). In a screen for tobacco genes that were down-regulated in a tobacco mutant with altered regulation of nicotine biosynthesis, we identified two homologous MPO cDNAs which encode diamine oxidases of a particular subclass. Tobacco MPO genes were expressed specifically in the root, and up-regulated by jasmonate treatment. Recombinant MPO protein expressed in Escherichia coli formed a homodimer and deaminated N-methylputrescine more efficiently than symmetrical diamines. These results indicate that MPO evolved from general diamine oxidases to function effectively in nicotine biosynthesis.

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