Interplay between Heat Shock Protein 90 and HY5 controls PhANG expression in response to the GUN5 plastid signal.
The presence of genes encoding organellar proteins in different cellular compartments necessitates a tight coordination of expression by the different genomes of the eukaryotic cell. This coordination of gene expression is achieved by organelle-to-nucleus or retrograde communication. Stress-induced perturbations of the tetrapyrrole pathway trigger large changes in nuclear gene expression in plants. Recently, we identified HSP90 proteins as ligands of the putative plastid signal Mg-ProtoIX. In order to investigate whether the interaction between HSP90 and Mg-ProtoIX is biologically relevant, we produced transgenic lines with reduced levels of cytosolic HSP90 in wild-type and gun5 backgrounds. Our work reveals that HSP90 proteins respond to the tetrapyrrole-mediated plastid signal to control expression of photosynthesis-associated nuclear genes (PhANG) during the response to oxidative stress. We also show that the hy5 mutant is insensitive to tetrapyrrole accumulation and that Mg-ProtoIX, cytosolic HSP90, and HY5 are all part of the same signaling pathway. These findings suggest that a regulatory complex controlling gene expression that includes HSP90 proteins and a transcription factor that is modified by tetrapyrroles in response to changes in the environment is evolutionarily conserved between yeast and plants.
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden.
Peter
P
Kindgren
Louise
L
Norén
Juan de Dios Barajas
Jde D
López
Jehad
J
Shaikhali
Asa
A
Strand
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D018841:HSP90 Heat-Shock Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008190:Lyases / Q000378:metabolism*; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism*; D010641:Phenotype; D010788:Photosynthesis / Q000187:drug effects / Q000235:genetics*; D018087:Plastids / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding; D011524:Protoporphyrins / Q000494:pharmacology*; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D018841:HSP90 Heat-Shock Proteins; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D011524:Protoporphyrins; C039629:magnesium protoporphyrin; D008190:Lyases; C561080:GUN5 protein, Arabidopsis