Functional properties and regulatory complexity of a minimal RBCS light-responsive unit activated by phytochrome, cryptochrome, and plastid signals.
Light-inducible promoters are able to respond to a wide spectrum of light through multiple photoreceptor systems. Several cis-acting elements have been identified as components of light-responsive promoter elements; however, none of these regulatory elements by itself appears to be sufficient to confer light responsiveness; rather, the combination of at least two elements seems to be required. Using phylogenetic structural analysis, we have identified conserved DNA modular arrays (CMAs) associated with light-responsive promoter regions that have been conserved throughout the evolutionary radiation of angiosperms. Here, we report the functional characterization of CMA5, a native 52-bp fragment of the Nicotiana plumbaginifolia rbcS 8B promoter, which contains an I- and a G-box cis-element. CMA5 behaves as a light-responsive minimal unit capable of activating a heterologous minimal promoter in a phytochrome-, cryptochrome-, and plastid-dependent manner. We also show that CMA5 light induction requires HY5 and that downstream negative regulators COP (constitutive photomorphogenic)/DET (de-etiolated) regulate its activity. Our results show that the simplest light-responsive promoter element from photosynthesis-associated genes described to date is the common target for different signals involved in light regulation. The possible mechanism involved in light-transcriptional regulation and tissue specificity of combinatorial elements units is discussed.
Martínez-Hernández
Aída
A
Departamento de Ingeniería Genética de Plantas, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 629, 36500 Irapuato, Guanajuato, México.
López-Ochoa
Luisa
L
Argüello-Astorga
Gerardo
G
Herrera-Estrella
Luis
L
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D056931:Cryptochromes; D003624:Darkness; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D008027:Light; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D017956:Photoreceptor Cells, Invertebrate; D010834:Phytochrome / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D030821:Plants, Genetically Modified; D018087:Plastids / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D043562:Receptors, G-Protein-Coupled; D020218:Response Elements / Q000235:genetics; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics*; D015398:Signal Transduction; D014158:Transcription, Genetic / Q000528:radiation effects
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila; D010834:Phytochrome; D005966:Glucuronidase; D012273:Ribulose-Bisphosphate Carboxylase