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Plant Physiol

Title:		Vacuole-localized berberine bridge enzyme-like proteins are required for a late step of nicotine biosynthesis in tobacco
Author(s):		Kajikawa M; Shoji T; Kato A; Hashimoto T;
Address:		"Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan"
Journal Title:		Plant Physiol
Year:		2011
Volume:		20110222
Issue:		4
Page Number:		2010 - 2022
DOI:		10.1104/pp.110.170878
ISSN/ISBN:		1532-2548 (Electronic) 0032-0889 (Print) 0032-0889 (Linking)
Abstract:		"Tobacco (Nicotiana tabacum) plants synthesize nicotine and related pyridine-type alkaloids, such as anatabine, in their roots and accumulate them in their aerial parts as chemical defenses against herbivores. Herbivory-induced jasmonate signaling activates structural genes for nicotine biosynthesis and transport by way of the NICOTINE (NIC) regulatory loci. The biosynthesis of tobacco alkaloids involves the condensation of an unidentified nicotinic acid-derived metabolite with the N-methylpyrrolinium cation or with itself, but the exact enzymatic reactions and enzymes involved remain unclear. Here, we report that jasmonate-inducible tobacco genes encoding flavin-containing oxidases of the berberine bridge enzyme family (BBLs) are expressed in the roots and regulated by the NIC loci. When expression of the BBL genes was suppressed in tobacco hairy roots or in tobacco plants, nicotine production was highly reduced, with a gradual accumulation of a novel nicotine metabolite, dihydromethanicotine. In the jasmonate-elicited cultured tobacco cells, suppression of BBL expression efficiently inhibited the formation of anatabine and other pyridine alkaloids. Subcellular fractionation and localization of green fluorescent protein-tagged BBLs showed that BBLs are localized in the vacuoles. These results indicate that BBLs are involved in a late oxidation step subsequent to the pyridine ring condensation reaction in the biosynthesis of tobacco alkaloids"
Keywords:		"Berberine/*chemistry Cyclopentanes Gene Expression Profiling Gene Expression Regulation, Plant Gene Knockdown Techniques Nicotine/*biosynthesis Oxylipins Plant Proteins/genetics/*metabolism Plants, Genetically Modified/enzymology/genetics RNA, Plant/genet;"
Notes:		"MedlineKajikawa, Masataka Shoji, Tsubasa Kato, Akira Hashimoto, Takashi eng Research Support, Non-U.S. Gov't 2011/02/24 Plant Physiol. 2011 Apr; 155(4):2010-22. doi: 10.1104/pp.110.170878. Epub 2011 Feb 22"