Details
| Original language | English |
|---|---|
| Pages (from-to) | 155-164 |
| Number of pages | 10 |
| Journal | Plant Journal |
| Volume | 22 |
| Issue number | 2 |
| Publication status | Published - 1 Apr 2000 |
Abstract
The chelation of Fe2+ and Mg2+ ions forms protoheme IX and Mg-protoporphyrin IX, respectively, and the latter is an intermediate in chlorophyll synthesis. Active magnesium protoporphyrin IX chelatase (Mg-chelatase) is an enzyme complex consisting of three different subunits. To investigate the function of the CHL I subunit of Mg-chelatase and the effects of modified Mg-chelatase activity on the tetrapyrrole biosynthetic pathway, we characterized N. tabacum transformants carrying gene constructs with the Chl I cDNA sequence in antisense and sense orientation under the control of the CaMV 35S promoter. Both elevated and diminished levels of Chl I mRNA and Chl I protein led to reduced Mg-chelatase activities, reflecting a perturbation of the assembly of the enzyme complex. The transformed plants did not accumulate the substrate of Mg-chelatase, protoporphyrin IX, but the leaves contained less chlorophyll and possessed increased chlorophyll(a/b) ratios, as well as a deficiency of light-harvesting chlorophyll binding proteins of photosystems I and II. The expression and activity of several tetrapyrrolic enzymes were reduced in parallel to lower the Mg-chelatase activity. Consistent with the lower chlorophyll contents, the rate-limiting synthesis of 5-aminolevulinate was also decreased in the transgenic lines analyzed. The consequence of reduced Mg-chelatase on early and late steps of chlorophyll synthesis, and on the organization of light harvesting complexes is discussed.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Genetics
- Agricultural and Biological Sciences(all)
- Plant Science
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology
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In: Plant Journal, Vol. 22, No. 2, 01.04.2000, p. 155-164.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Decreased and increased expression of the subunit CHL I diminishes Mg chelatase activity and reduces chlorophyll synthesis in transgenic tobacco plants
AU - Papenbrock, Jutta
AU - Pfündel, Erhard
AU - Mock, Hans Peter
AU - Grimm, Bernhard
PY - 2000/4/1
Y1 - 2000/4/1
N2 - The chelation of Fe2+ and Mg2+ ions forms protoheme IX and Mg-protoporphyrin IX, respectively, and the latter is an intermediate in chlorophyll synthesis. Active magnesium protoporphyrin IX chelatase (Mg-chelatase) is an enzyme complex consisting of three different subunits. To investigate the function of the CHL I subunit of Mg-chelatase and the effects of modified Mg-chelatase activity on the tetrapyrrole biosynthetic pathway, we characterized N. tabacum transformants carrying gene constructs with the Chl I cDNA sequence in antisense and sense orientation under the control of the CaMV 35S promoter. Both elevated and diminished levels of Chl I mRNA and Chl I protein led to reduced Mg-chelatase activities, reflecting a perturbation of the assembly of the enzyme complex. The transformed plants did not accumulate the substrate of Mg-chelatase, protoporphyrin IX, but the leaves contained less chlorophyll and possessed increased chlorophyll(a/b) ratios, as well as a deficiency of light-harvesting chlorophyll binding proteins of photosystems I and II. The expression and activity of several tetrapyrrolic enzymes were reduced in parallel to lower the Mg-chelatase activity. Consistent with the lower chlorophyll contents, the rate-limiting synthesis of 5-aminolevulinate was also decreased in the transgenic lines analyzed. The consequence of reduced Mg-chelatase on early and late steps of chlorophyll synthesis, and on the organization of light harvesting complexes is discussed.
AB - The chelation of Fe2+ and Mg2+ ions forms protoheme IX and Mg-protoporphyrin IX, respectively, and the latter is an intermediate in chlorophyll synthesis. Active magnesium protoporphyrin IX chelatase (Mg-chelatase) is an enzyme complex consisting of three different subunits. To investigate the function of the CHL I subunit of Mg-chelatase and the effects of modified Mg-chelatase activity on the tetrapyrrole biosynthetic pathway, we characterized N. tabacum transformants carrying gene constructs with the Chl I cDNA sequence in antisense and sense orientation under the control of the CaMV 35S promoter. Both elevated and diminished levels of Chl I mRNA and Chl I protein led to reduced Mg-chelatase activities, reflecting a perturbation of the assembly of the enzyme complex. The transformed plants did not accumulate the substrate of Mg-chelatase, protoporphyrin IX, but the leaves contained less chlorophyll and possessed increased chlorophyll(a/b) ratios, as well as a deficiency of light-harvesting chlorophyll binding proteins of photosystems I and II. The expression and activity of several tetrapyrrolic enzymes were reduced in parallel to lower the Mg-chelatase activity. Consistent with the lower chlorophyll contents, the rate-limiting synthesis of 5-aminolevulinate was also decreased in the transgenic lines analyzed. The consequence of reduced Mg-chelatase on early and late steps of chlorophyll synthesis, and on the organization of light harvesting complexes is discussed.
UR - http://www.scopus.com/inward/record.url?scp=0343294295&partnerID=8YFLogxK
U2 - 10.1046/j.1365-313X.2000.00724.x
DO - 10.1046/j.1365-313X.2000.00724.x
M3 - Article
C2 - 10792831
AN - SCOPUS:0343294295
VL - 22
SP - 155
EP - 164
JO - Plant Journal
JF - Plant Journal
SN - 0960-7412
IS - 2
ER -