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Publication Type J
Authors Rathinasabapathi, B., C. Sigua, J. Ho and D. A. Gage
Title Osmoprotectant beta-alanine betaine synthesis in the Plumbaginaceae: S-adenosyl-L-methionine dependent N-methylation of beta-alanine to its betaine is via N-methyl and N,N-dimethyl beta-alanines
Source Physiologia Plantarum
Author Keywords CHOLINE MONOOXYGENASE STRESS TOLERANCE ESCHERICHIA-COLI METHYLTRANSFERASE PURIFICATION SPINACH GENE PROTEIN BINDING PATHWAY
Abstract beta-Alanine betaine is an osmoprotective compound accumulated by most members of the plant family Plumbaginaceae. Leaf and root tissues of Limonium latifolium known to accumulate beta-alanine betaine readily convert supplied beta-alanine to beta-alanine betaine. To identify the intermediates and the enzymes involved in beta-alanine betaine synthesis, radiotracer experiments using [C-14] formate were employed. These studies demonstrate that beta-alanine betaine is synthesized from beta-alanine via N-methyl and N,N-dimethyl beta-alanines. A rapid and sensitive radiometric assay was developed to measure N-methyltransferase (NMT) activities by using [methyl-C-14] or [methyl-H-3] S-adenosyl-L-methionine (AdoMet) as the methyl donor, Leaf extracts from beta-alanine betaine accumulators - Armeria maritima, L. latifolium and L. ramosissimum - had detectable NMT activities while none were found in L. perezii, a species that does not accumulate beta-alanine betaine. The MMT activities were further characterized from the leaves of L. latifolium. The activities had a pH optimum of 8.0, were soluble and inhibited by S-adenosyl-L-homocysteine. Extractable activities were similar from plants grown under control and salinity stress conditions. Radiolabeling with [C-14] L-aspartic acid indicated that, unlike in bacteria, decarboxylation of L-aspartic acid is not the source of beta-alanine in the Plumbaginaceae.
Author Address Univ Florida, Dept Hort Sci, Plant Mol & Cellular Biol Program, Gainesville, FL 32611 USA. Michigan State Univ, Dept Biochem, E Lansing, MI 48824 USA. Rathinasabapathi, B (reprint author), Univ Florida, Dept Hort Sci, Plant Mol & Cellular Biol Program, Gainesville, FL 32611 USA.
ISSN 0031-9317
ISBN 0031-9317
Publication Date Jul
Year Published 2000
Volume 109
Issue 3
Beginning Page 225-231
Digital Object Identifier (DOI) 10.1034/j.1399-3054.2000.100302.x
Unique Article Identifier WOS:000088190700002
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