title: GUN4, a regulator of chlorophyll synthesis and intracellular signaling.
abstract: Nuclear genes control plastid differentiation in response to developmental signals, environmental signals, and retrograde signals from plastids themselves. In return, plastids emit signals that are essential for proper expression of many nuclear photosynthetic genes. Accumulation of magnesium-protoporphyrin IX (Mg-Proto), an intermediate in chlorophyll biosynthesis, is a plastid signal that represses nuclear transcription through a signaling pathway that, in Arabidopsis, requires the GUN4 gene. GUN4 binds the product and substrate of Mg- chelatase, an enzyme that produces Mg-Proto, and activates Mg-chelatase. Thus, GUN4 participates in plastid-to-nucleus signaling by regulating Mg-Proto synthesis or trafficking.
authors.affiliation: Howard Hughes Medical Institute, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Larkin
authors.forename: Jose M
authors.initials: JM
authors.lastname: Alonso
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Ecker
authors.forename: Joanne
authors.initials: J
authors.lastname: Chory
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D002734:Chlorophyll / Q000096:biosynthesis*; D002736:Chloroplasts / Q000378:metabolism*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D003905:Deuteroporphyrins / Q000378:metabolism; D004789:Enzyme Activation; D017343:Genes, Plant; D017930:Genes, Reporter; D047908:Intracellular Signaling Peptides and Proteins; D008190:Lyases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D020125:Mutation, Missense; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport; D011524:Protoporphyrins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D020524:Thylakoids / Q000737:chemistry / Q000201:enzymology
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D003905:Deuteroporphyrins; C472017:GUN4 protein, Arabidopsis; D047908:Intracellular Signaling Peptides and Proteins; D021122:Protein Subunits; D011524:Protoporphyrins; D011994:Recombinant Proteins; D002734:Chlorophyll; C028839:deuteroporphyrin-IX; C028025:protoporphyrin IX; D008190:Lyases; C086788:magnesium chelatase; D008274:Magnesium