De-etiolated 1 and damaged DNA binding protein 1 interact to regulate Arabidopsis photomorphogenesis.
BACKGROUND
Plant development is exquisitely sensitive to light. Seedlings grown in the dark have a developmentally arrested etiolated phenotype, whereas in the light they develop leaves and complete their life cycle. Arabidopsis de-etiolated 1 (det1) mutants develop like light-grown seedlings even when grown in the dark. DET1 encodes a nuclear protein that appears to act downstream from multiple photoreceptors to regulate morphogenesis and gene expression in response to light. However, its function has remained unknown.


RESULTS
We used microarrays to examine defects in transcription in dark-grown det1 seedlings. We found extensive changes in gene expression, including many of the transcriptional responses observed in light-treated wild-type seedlings. We used an epitope-tagging approach to determine the basis of DET1 function. GFP-DET1 rescues the det1 phenotype, is localized to the nucleus, and forms an approximately 350 kDa complex, which is required for full DET1 activity. We affinity-purified the DET1 complex and identified an approximately 120 kDa copurifying protein that is the plant homolog of UV-Damaged DNA Binding Protein 1 (DDB1), a protein implicated in the human disease xeroderma pigmentosa. A null mutation in Arabidopsis DDB1A results in no obvious phenotype on its own, yet it enhances the phenotype of a weak det1 allele.


CONCLUSIONS
DET1 and DDB1 interact both biochemically and genetically. In animal cells, DDB1 interacts with histone acetyltransferase complexes. The DET1/DDB1 complex may regulate gene expression in response to light via recruitment of HAT activity. Thus, DET1, whose sequence is conserved in both animals and plants, may play a direct role in the regulation of many genes.
Schroeder
Dana F
DF
Plant Biology Laboratory, La Jolla, CA 92037, USA.
Gahrtz
Manfred
M
Maxwell
Bridey B
BB
Cook
R Kimberley
RK
Kan
Jack M
JM
Alonso
José M
JM
Ecker
Joseph R
JR
Chory
Joanne
J
D000123:Acetyltransferases / Q000502:physiology; D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000828:Animal Population Groups / Q000235:genetics; D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D003624:Darkness; D004843:Epistasis, Genetic; D000939:Epitopes; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D051548:Histone Acetyltransferases; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D008954:Models, Biological; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics / Q000528:radiation effects; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D025941:Protein Interaction Mapping; D011993:Recombinant Fusion Proteins / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology; D036226:Seedlings / Q000502:physiology / Q000528:radiation effects; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic / Q000235:genetics / Q000528:radiation effects
D029681:Arabidopsis Proteins; C088435:DET1 protein, Arabidopsis; D004268:DNA-Binding Proteins; D000939:Epitopes; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D000123:Acetyltransferases; D051548:Histone Acetyltransferases