TY - JOUR

T1 - Impaired expression of the plastidic ferrochelatase by antisense RNA synthesis leads to a necrotic phenotype of transformed tobacco plants

AU - Papenbrock, Jutta

AU - Mishra, Sanjay

AU - Mock, Hans Peter

AU - Kruse, Elisabeth

AU - Schmidt, Eva Kathrin

AU - Petersmann, Astrid

AU - Braun, Hans Peter

AU - Grimm, Bernhard

PY - 2001/12/23

Y1 - 2001/12/23

N2 - 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 (FeChll). 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.

AB - 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 (FeChll). 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.

KW - 5-aminolevulinic acid synthesis

KW - Chlorophyll

KW - Heme

KW - Magnesium-chelatase

KW - Metabolic engineering

KW - Protoporphyrin IX

KW - Transgenic plants

UR - http://www.scopus.com/inward/record.url?scp=0034762470&partnerID=8YFLogxK

U2 - 10.1046/j.1365-313X.2001.01126.x

DO - 10.1046/j.1365-313X.2001.01126.x

M3 - Article

C2 - 11696185

AN - SCOPUS:0034762470

VL - 28

SP - 41

EP - 50

JO - Plant Journal

JF - Plant Journal

SN - 0960-7412

IS - 1

ER -