Functional characterization of the HD-ZIP IV transcription factor OCL1 from maize.
OCL1 (OUTER CELL LAYER1) encodes a maize HD-ZIP class IV transcription factor (TF) characterized by the presence of a homeo DNA-binding domain (HD), a dimerization leucine zipper domain (ZIP), and a steroidogenic acute regulatory protein (StAR)-related lipid transfer domain (START) involved in lipid transport in animals but the function of which is still unknown in plants. By combining yeast and plant trans-activation assays, the transcriptional activation domain of OCL1 was localized to 85 amino acids in the N-terminal part of the START domain. Full-length OCL1 devoid of this activation domain is unable to trans-activate a reporter gene under the control of a minimal promoter fused to six repeats of the L1 box, a cis-element present in target genes of HD-ZIP IV TFs in Arabidopsis. In addition, ectopic expression of OCL1 leads to pleiotropic phenotypic aberrations in transgenic maize plants, the most conspicuous one being a strong delay in flowering time which is correlated with the misexpression of molecular markers for floral transition such as ZMM4 (Zea Mays MADS-box4) or DLF1 (DELAYED FLOWERING1). As suggested by the interaction in planta between OCL1 and SWI3C1, a bona fide subunit of the SWI/SNF complex, OCL1 may modulate transcriptional activity of its target genes by interaction with a chromatin remodelling complex.
Depège-Fargeix
Nathalie
N
Université de Lyon, Ecole Normale Supérieure de Lyon, Université Lyon 1, IFR128 BioSciences Lyon Gerland, Unité Reproduction et Développement des Plantes, F-69364 Lyon, France.
Javelle
Marie
M
Chambrier
Pierre
P
Frangne
Nathalie
N
Gerentes
Denise
D
Perez
Pascual
P
Rogowsky
Peter M
PM
Vernoud
Vanessa
V
D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016350:Leucine Zippers; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015533:Transcriptional Activation; D003313:Zea mays / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D018398:Homeodomain Proteins; D008565:Membrane Proteins; C120341:OCL1 protein, Zea mays; D010940:Plant Proteins