title: Induced deactivation of genes encoding chlorophyll biosynthesis enzymes disentangles tetrapyrrole-mediated retrograde signaling.
abstract: In photosynthetic organisms, tetrapyrrole-mediated retrograde signals are proposed to contribute to a balanced nuclear gene expression (NGE) in response to metabolic activity in chloroplasts. We followed an experimental short-term approach that allowed the assessment of modified NGE during the first hours of specifically modified enzymatic steps of the Mg branch of tetrapyrrole biosynthesis, when pleiotropic effects of other signals can be avoided. In response to 24-h-induced silencing of CHLH, CHLM, and CHL27 encoding the CHLH subunit of Mg chelatase, the Mg protoporphyrin methyltransferase and Mg protoporphyrin monomethylester cyclase, respectively, deactivated gene expression rapidly led to reduced activity of the corresponding enzymes and altered Mg porphyrin levels. But NGE was not substantially altered. When these three genes were continuously inactivated for up to 4 d, changes of transcript levels of nuclear genes were determined. CHL27 silencing for more than 24h results in necrotic leaf lesions and modulated transcript levels of oxidative stress-responsive and photosynthesis-associated nuclear genes (PhANGs). The prolonged deactivation of CHLH and CHLM results in slightly elevated transcript levels of PhANGs and tetrapyrrole-associated genes. These time-resolved studies indicate a complex scenario for the contribution of tetrapyrrole biosynthesis on NGE mediated by (1)O2-induced signaling and feedback-regulated ALA synthesis.
authors.affiliation: Institute of Biology/Plant Physiology, Humboldt University Berlin, Philippstr. 13, Building 12, D 10115 Berlin, Germany.
authors.forename: Hagen
authors.initials: H
authors.lastname: Schlicke
authors.affiliation: Institute of Biology/Plant Physiology, Humboldt University Berlin, Philippstr. 13, Building 12, D 10115 Berlin, Germany.
authors.forename: Annabel Salinas
authors.initials: AS
authors.lastname: Hartwig
authors.affiliation: Institute of Biology/Plant Physiology, Humboldt University Berlin, Philippstr. 13, Building 12, D 10115 Berlin, Germany.
authors.forename: Vivien
authors.initials: V
authors.lastname: Firtzlaff
authors.affiliation: Institute of Biology/Plant Physiology, Humboldt University Berlin, Philippstr. 13, Building 12, D 10115 Berlin, Germany.
authors.forename: Andreas S
authors.initials: AS
authors.lastname: Richter
authors.affiliation: Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Glässer
authors.affiliation: Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Maier
authors.affiliation: Max-Planck-Institute for Plant Breeding Research, Plant Proteomics and Mass Spectrometry Group, Carl-von-Linné Weg 10, 50829 Cologne, Germany.
authors.forename: Iris
authors.initials: I
authors.lastname: Finkemeier
authors.affiliation: Institute of Biology/Plant Physiology, Humboldt University Berlin, Philippstr. 13, Building 12, D 10115 Berlin, Germany bernhard.grimm@rz.hu-berlin.de.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Grimm
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics; D002734:Chlorophyll / Q000096:biosynthesis*; D020868:Gene Silencing; D017343:Genes, Plant / Q000235:genetics*; D008274:Magnesium / Q000378:metabolism; D010641:Phenotype; D011524:Protoporphyrins / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D045725:Tetrapyrroles / Q000378:metabolism*; D013997:Time Factors; D059467:Transcriptome
chemical_list: D011524:Protoporphyrins; D012333:RNA, Messenger; D045725:Tetrapyrroles; D002734:Chlorophyll; D008274:Magnesium
keywords: Mg protoporphyrin.; plastid signal; retrograde signal; tetrapyrrole metabolism; transcription analysis