Biosynthesis of Phytosiderophores : In Vitro Biosynthesis of 2'-Deoxymugineic Acid from l-Methionine and Nicotianamine.
2' -Deoxymugineic acid (DMA), one of mugineic acid-family phytosiderophores (MAs), was synthesized in vitro both from l-methionine and from nicotianamine (NA) with a cell-free system derived from root tips of iron-deficient barley (Hordeum vulgare L.). The reactions producing DMA from NA needed an amino group acceptor (i.e. 2-oxoglutarate, pyruvate, or oxalacetic acid) and a reductant (i.e. NADH or NADPH). The activity of the enzymes to produce NA from l-methionine was the highest at about pH 9. This biosynthetic activity was markedly induced by iron-deficiency stress. The synthesis of NA from S-adenosyl-l-methionine was more efficient than from l-methionine. From the results with the cell-free system reported here, we propose a revised biosynthetic pathway of MAs.
Shojima
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Laboratory of Plant Nutrition & Fertilizers, Department of Agricultural Chemistry, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan.
Nishizawa
N K
NK
Fushiya
S
S
Nozoe
S
S
Irifune
T
T
Mori
S
S