Details
| Original language | English |
|---|---|
| Pages (from-to) | 1161-1169 |
| Number of pages | 9 |
| Journal | Plant physiology |
| Volume | 122 |
| Issue number | 4 |
| Publication status | Published - 1 Apr 2000 |
Abstract
Magnesium-protoporphyrin IX chelatase (Mg-chelatase) is located at the branchpoint of tetrapyrrole biosynthesis, at which point protoporphyrin IX is distributed for the synthesis of chlorophyll and heme. We investigated the regulatory contribution of Mg-chelatase to the flow of metabolites. In plants, the enzyme complex consists of three subunits, designated CHL D, CHL I, and CHL H. Transgenic tobacco (Nicotiana tabacum) plants expressing antisense RNA for the Mg-chelatase subunit CHL H were analyzed to elucidate further the role of Mg-chelatase in the distribution of protoporphyrin IX into the branched tetrapyrrolic pathway. The transgenic plants displayed a reduced growth rate and chlorophyll deficiency. Both phenotypical properties were correlated with lower Mg-chelatase activity. Unexpectedly, less protoporphyrin IX and heme accumulated, and a decrease in 5-aminolevulinate (ALA)-synthesizing capacity and ALA dehydratase activity paralleled the progressive reduction in Mg-chelatase activity in the transformants compared with control plants. The reduced activities of the early enzymatic steps corresponded with lower levels of transcripts encoding glutamyl-tRNA reductase and ALA-dehydratase. The decreased expression and activities of early enzymes in the pathway could be explained by a feedback-controlled mechanism in response to lower Mg-chelatase activity. We discuss intercompartmental signaling that synchronizes the activities of the first steps in tetrapyrrolic metabolism with the late steps for the synthesis of end products.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physiology
- Biochemistry, Genetics and Molecular Biology(all)
- Genetics
- Agricultural and Biological Sciences(all)
- Plant Science
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In: Plant physiology, Vol. 122, No. 4, 01.04.2000, p. 1161-1169.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Role of magnesium chelatase activity in the early steps of the tetrapyrrole biosynthetic pathway
AU - Papenbrock, Jutta
AU - Mock, Hans Peter
AU - Tanaka, Ryouichi
AU - Kruse, Elisabeth
AU - Grimm, Bernhard
PY - 2000/4/1
Y1 - 2000/4/1
N2 - Magnesium-protoporphyrin IX chelatase (Mg-chelatase) is located at the branchpoint of tetrapyrrole biosynthesis, at which point protoporphyrin IX is distributed for the synthesis of chlorophyll and heme. We investigated the regulatory contribution of Mg-chelatase to the flow of metabolites. In plants, the enzyme complex consists of three subunits, designated CHL D, CHL I, and CHL H. Transgenic tobacco (Nicotiana tabacum) plants expressing antisense RNA for the Mg-chelatase subunit CHL H were analyzed to elucidate further the role of Mg-chelatase in the distribution of protoporphyrin IX into the branched tetrapyrrolic pathway. The transgenic plants displayed a reduced growth rate and chlorophyll deficiency. Both phenotypical properties were correlated with lower Mg-chelatase activity. Unexpectedly, less protoporphyrin IX and heme accumulated, and a decrease in 5-aminolevulinate (ALA)-synthesizing capacity and ALA dehydratase activity paralleled the progressive reduction in Mg-chelatase activity in the transformants compared with control plants. The reduced activities of the early enzymatic steps corresponded with lower levels of transcripts encoding glutamyl-tRNA reductase and ALA-dehydratase. The decreased expression and activities of early enzymes in the pathway could be explained by a feedback-controlled mechanism in response to lower Mg-chelatase activity. We discuss intercompartmental signaling that synchronizes the activities of the first steps in tetrapyrrolic metabolism with the late steps for the synthesis of end products.
AB - Magnesium-protoporphyrin IX chelatase (Mg-chelatase) is located at the branchpoint of tetrapyrrole biosynthesis, at which point protoporphyrin IX is distributed for the synthesis of chlorophyll and heme. We investigated the regulatory contribution of Mg-chelatase to the flow of metabolites. In plants, the enzyme complex consists of three subunits, designated CHL D, CHL I, and CHL H. Transgenic tobacco (Nicotiana tabacum) plants expressing antisense RNA for the Mg-chelatase subunit CHL H were analyzed to elucidate further the role of Mg-chelatase in the distribution of protoporphyrin IX into the branched tetrapyrrolic pathway. The transgenic plants displayed a reduced growth rate and chlorophyll deficiency. Both phenotypical properties were correlated with lower Mg-chelatase activity. Unexpectedly, less protoporphyrin IX and heme accumulated, and a decrease in 5-aminolevulinate (ALA)-synthesizing capacity and ALA dehydratase activity paralleled the progressive reduction in Mg-chelatase activity in the transformants compared with control plants. The reduced activities of the early enzymatic steps corresponded with lower levels of transcripts encoding glutamyl-tRNA reductase and ALA-dehydratase. The decreased expression and activities of early enzymes in the pathway could be explained by a feedback-controlled mechanism in response to lower Mg-chelatase activity. We discuss intercompartmental signaling that synchronizes the activities of the first steps in tetrapyrrolic metabolism with the late steps for the synthesis of end products.
UR - http://www.scopus.com/inward/record.url?scp=0034003620&partnerID=8YFLogxK
M3 - Article
C2 - 10759511
AN - SCOPUS:0034003620
VL - 122
SP - 1161
EP - 1169
JO - Plant physiology
JF - Plant physiology
SN - 0032-0889
IS - 4
ER -