Pathways of intracellular communication: tetrapyrroles and plastid-to-nucleus signaling.
Retrograde plastid-to-nucleus signaling plays a central role in coordinating nuclear and plastid gene expression. The gun (genomes uncoupled) mutants of Arabidopsis have been used to demonstrate that Mg-protoporphyrin (Mg-Proto) acts as a plastid signal to repress the transcription of nuclear photosynthesis genes (1). It is unclear how Mg-Proto triggers repression, but several components of this pathway have been recently identified. These include the products of GUN4 and GUN5. GUN5 is the ChlH subunit of Mg-chelatase, which produces Mg-Proto, and GUN4 is a regulator of ChlH activity (2). GUN4 might also play a role in photoprotection and in the trafficking of Mg-Proto.
Rodermel
Steve
S
Department of Genetics, Developmental and Cellular Biology, and the Plant Sciences Institute, Iowa State University, Ames, IA 50011, USA. rodermel@iastate.edu
Park
Sungsoon
S
D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000502:physiology; D002352:Carrier Proteins / Q000502:physiology; D002450:Cell Communication / Q000502:physiology*; D002467:Cell Nucleus / Q000502:physiology*; D018745:Genome, Plant; D047908:Intracellular Signaling Peptides and Proteins; D008954:Models, Biological; D010788:Photosynthesis / Q000235:genetics; D018087:Plastids / Q000502:physiology; D011758:Pyrroles / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D045725:Tetrapyrroles; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D002352:Carrier Proteins; C472017:GUN4 protein, Arabidopsis; D047908:Intracellular Signaling Peptides and Proteins; D011758:Pyrroles; D045725:Tetrapyrroles