Transgenic Tobacco Lines Expressing Sense or Antisense FERROCHELATASE 1 RNA Show Modified Ferrochelatase Activity in Roots and Provide Experimental Evidence for Dual Localization of Ferrochelatase 1.
In plants, two genes encode ferrochelatase (FC), which catalyzes iron chelation into protoporphyrin IX at the final step of heme biosynthesis. FERROCHELATASE1 (FC1) is continuously, but weakly expressed in roots and leaves, while FC2 is dominantly active in leaves. As a continuation of previous studies on the physiological consequences of FC2 inactivation in tobacco, we aimed to assign FC1 function in plant organs. While reduced FC2 expression leads to protoporphyrin IX accumulation in leaves, FC1 down-regulation and overproduction caused reduced and elevated FC activity in root tissue, respectively, but were not associated with changes in macroscopic phenotype, plant development or leaf pigmentation. In contrast to the lower heme content resulting from a deficiency of the dominant FC2 expression in leaves, a reduction of FC1 in roots and leaves does not significantly disturb heme accumulation. The FC1 overexpression was used for an additional approach to re-examine FC activity in mitochondria. Transgenic FC1 protein was immunologically shown to be present in mitochondria. Although matching only a small portion of total cellular FC activity, the mitochondrial FC activity in a FC1 overexpressor line increased 5-fold in comparison with wild-type mitochondria. Thus, it is suggested that FC1 contributes to mitochondrial heme synthesis.
Humboldt-University Berlin, Institute of Biology/Plant Physiology, Philippstr.13, Building 12, D-10115 Berlin, Germany.
Daniel
D
Hey
Humboldt-University Berlin, Institute of Biology/Plant Physiology, Philippstr.13, Building 12, D-10115 Berlin, Germany.
Patricia
P
Ortega-Rodes
Humboldt-University Berlin, Institute of Biology/Plant Physiology, Philippstr.13, Building 12, D-10115 Berlin, Germany.
Tingting
T
Fan
Humboldt-University Berlin, Institute of Biology/Plant Physiology, Philippstr.13, Building 12, D-10115 Berlin, Germany.
Florian
F
Schnurrer
Humboldt-University Berlin, Institute of Biology/Plant Physiology, Philippstr.13, Building 12, D-10115 Berlin, Germany.
Lea
L
Brings
Humboldt-University Berlin, Institute of Biology/Plant Physiology, Philippstr.13, Building 12, D-10115 Berlin, Germany.
Boris
B
Hedtke
Humboldt-University Berlin, Institute of Biology/Plant Physiology, Philippstr.13, Building 12, D-10115 Berlin, Germany bernhard.grimm@hu-berlin.de.
Bernhard
B
Grimm
D015536:Down-Regulation; D005294:Ferrochelatase / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006418:Heme / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D009928:Organ Specificity; D010641:Phenotype; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics; D030821:Plants, Genetically Modified; D021381:Protein Transport; D011524:Protoporphyrins / Q000378:metabolism*; D016372:RNA, Antisense / Q000235:genetics; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics
D010940:Plant Proteins; D011524:Protoporphyrins; D016372:RNA, Antisense; D006418:Heme; C028025:protoporphyrin IX; D005294:Ferrochelatase
ALA synthesis; Heme biosynthesis; Mitochondria; Tetrapyrroles; Transgenic tobacco plants