TY - JOUR
T1 - Distinct Isoprenoid Origins of cis- and trans-Zeatin Biosyntheses in Arabidopsis
AU - Kasahara, Hiroyuki
AU - Takei, Kentaro
AU - Ueda, Nanae
AU - Hishiyama, Shojiro
AU - Yamaya, Tomoyuki
AU - Kamiya, Yuji
AU - Yamaguchi, Shinjiro
AU - Sakakibara, Hitoshi
PY - 2004/4/2
Y1 - 2004/4/2
N2 - Plants produce the common isoprenoid precursors isopentenyl diphosphate and dimethylallyl diphosphate (DMAPP) through the methylerythritol phosphate (MEP) pathway in plastids and the mevalonate (MVA) pathway in the cytosol. To assess which pathways contribute DMAPP for cytokinin biosynthesis, metabolites from each isoprenoid pathway were selectively labeled with 13C in Arabidopsis seedlings. Efficient 13C labeling was achieved by blocking the endogenous pathway genetically or chemically during the feed of a 13C labeled precursor specific to the MEP or MVA pathways. Liquid chromatography-mass spectrometry analysis demonstrated that the prenyl group of trans-zeatin (tZ) and isopentenyladenine is mainly produced through the MEP pathway. In comparison, a large fraction of the prenyl group of cis-zeatin (cZ) derivatives was provided by the MVA pathway. When expressed as fusion proteins with green fluorescent protein in Arabidopsis cells, four adenosine phosphate-isopentenyltransferases (AtIPT1, AtIPT3, AtIPT5, and AtIPT8) were found in plastids, in agreement with the idea that the MEP pathway primarily provides DMAPP to tZ and isopentenyladenine. On the other hand, AtIPT2, a tRNA isopentenyltransferase, was detected in the cytosol. Because the prenylated adenine moiety of tRNA is usually of the cZ type, the formation of cZ in Arabidopsis seedlings might involve the transfer of DMAPP from the MVA pathway to tRNA. Distinct origins of large proportions of DMAPP for tZ and cZ biosynthesis suggest that plants are able to separately modulate the level of these cytokinin species.
AB - Plants produce the common isoprenoid precursors isopentenyl diphosphate and dimethylallyl diphosphate (DMAPP) through the methylerythritol phosphate (MEP) pathway in plastids and the mevalonate (MVA) pathway in the cytosol. To assess which pathways contribute DMAPP for cytokinin biosynthesis, metabolites from each isoprenoid pathway were selectively labeled with 13C in Arabidopsis seedlings. Efficient 13C labeling was achieved by blocking the endogenous pathway genetically or chemically during the feed of a 13C labeled precursor specific to the MEP or MVA pathways. Liquid chromatography-mass spectrometry analysis demonstrated that the prenyl group of trans-zeatin (tZ) and isopentenyladenine is mainly produced through the MEP pathway. In comparison, a large fraction of the prenyl group of cis-zeatin (cZ) derivatives was provided by the MVA pathway. When expressed as fusion proteins with green fluorescent protein in Arabidopsis cells, four adenosine phosphate-isopentenyltransferases (AtIPT1, AtIPT3, AtIPT5, and AtIPT8) were found in plastids, in agreement with the idea that the MEP pathway primarily provides DMAPP to tZ and isopentenyladenine. On the other hand, AtIPT2, a tRNA isopentenyltransferase, was detected in the cytosol. Because the prenylated adenine moiety of tRNA is usually of the cZ type, the formation of cZ in Arabidopsis seedlings might involve the transfer of DMAPP from the MVA pathway to tRNA. Distinct origins of large proportions of DMAPP for tZ and cZ biosynthesis suggest that plants are able to separately modulate the level of these cytokinin species.
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U2 - 10.1074/jbc.M314195200
DO - 10.1074/jbc.M314195200
M3 - Article
C2 - 14726522
AN - SCOPUS:1842690050
VL - 279
SP - 14049
EP - 14054
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 14
ER -