Abstract
Protoporphyrin IX is the last common intermediate of tetrapyrrole biosynthesis. The chelation of a Mg2+ ion by magnesium chelatase and of a ferrous ion by ferrochelatase directs protoporphyrin IX towards the formation of chlorophyll and heme, respectively. A full length cDNA clone encoding a ferrochelatase was identified from a Nicotiana tabacum cDNA library. The encoded protein consists of 497 amino acid residues with a molecular weight of 55.4 kDa. In vitro import of the protein into chloroplasts and its location in stroma and thylakoids confirm its close relationship to the previously described Arabidopsis thaliana plastid-located ferrochelatase (FeChII). A 1700-bp tobacco FeCh cDNA sequence was expressed in Nicotiana tabacum cv. Samsun NN under the control of the CaMV 35S promoter in antisense orientation allowing investigation into the consequences of selective reduction of the plastidic ferrochelatase activity for protoporphyrin IX channeling in chloroplasts and for interactions between plastidic and mitochondrial heme synthesis. Leaves of several transformants showed a reduced chlorophyll content and, during development, a light intensity-dependent formation of necrotic leaf lesions. In comparison with wild-type plants the total ferrochelatase activity was decreased in transgenic lines leading to an accumulation of photosensitizing protoporphyrin IX. Ferrochelatase activity was reduced only in plastids but not in mitochondria of transgenic plants. By means of the specifically diminished ferrochelatase activity consequences of the selective inhibition of protoheme formation for the intracellular supply of heme can be investigated in the future.
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Claims 9
Claim · model-written summary
A full-length ferrochelatase cDNA was identified from tobacco.
- Taxon
- Nicotiana tabacum
Nicotiana tabacume0 - Gene
- ferrochelatasee0
- Outcome
- cDNA clonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A full length cDNA clone encoding a ferrochelatase was identified from a Nicotiana tabacum cDNA library.”
Claim · model-written summary
The encoded ferrochelatase protein has 497 amino acids and a molecular weight of 55.4 kDa.
Not reportedTaxon
Verbatim
e0“The encoded protein consists of 497 amino acid residues with a molecular weight of 55.4 kDa.”
Claim · model-written summary
The ferrochelatase protein was imported into chloroplasts and located in stroma and thylakoids.
- Outcome
- location in stroma and thylakoidse0
Not reportedTaxon
Verbatim
e0“In vitro import of the protein into chloroplasts and its location in stroma and thylakoids confirm its close relationship to the previously described Arabidopsis thaliana plastid-located ferrochelatase (FeChII).”
Claim · model-written summary
Several antisense tobacco transformants had reduced leaf chlorophyll content.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- transformantse0
- Outcome
- chlorophyll contente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaves of several transformants showed a reduced chlorophyll content”
t0“transformed tobacco plants”
Claim · model-written summary
Several transformants developed necrotic leaf lesions depending on light intensity.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- transformedt0
- Outcome
- necrotic leaf lesionse0
- Direction
- formatione0
- Qualifier
- light intensity-dependente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“during development, a light intensity-dependent formation of necrotic leaf lesions.”
t0“transformed tobacco plants”
Claim · model-written summary
Total ferrochelatase activity declined in transgenic lines relative to wild type.
- Treatment
- transgenic linese0
- Outcome
- total ferrochelatase activitye0
- Direction
- decreasede0
- Comparator
- wild-type plantse0
Not reportedTaxon
Verbatim
e0“In comparison with wild-type plants the total ferrochelatase activity was decreased in transgenic lines”
Claim · model-written summary
Protoporphyrin IX accumulated in transgenic tobacco lines.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- transgenic linese0
- Outcome
- accumulation of photosensitizing protoporphyrin IXe0
- Direction
- accumulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased in transgenic lines leading to an accumulation of photosensitizing protoporphyrin IX.”
t0“tobacco plants”
Claim · model-written summary
Ferrochelatase activity was reduced in plastids of transgenic plants.
- Organ / stage
- plastidse0
- Treatment
- transgenic plantse0
- Outcome
- Ferrochelatase activitye0
- Direction
- reducede0
Not reportedTaxonComparator
Verbatim
e0“Ferrochelatase activity was reduced only in plastids but not in mitochondria of transgenic plants.”
Claim · model-written summary
Ferrochelatase activity was not reduced in mitochondria of transgenic plants.
- Organ / stage
- mitochondriae0
- Treatment
- transgenic plantse0
- Outcome
- Ferrochelatase activitye0
- Direction
- not in mitochondriae0
Not reportedTaxonComparator
Verbatim
e0“Ferrochelatase activity was reduced only in plastids but not in mitochondria of transgenic plants.”
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