The CRYPTOCHROME1-dependent response to excess light is mediated through the transcriptional activators ZINC FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM LIKE1 and ZML2 in Arabidopsis.
Exposure of plants to light intensities that exceed the electron utilization capacity of the chloroplast has a dramatic impact on nuclear gene expression. The photoreceptor Cryptochrome 1 (cry1) is essential to the induction of genes encoding photoprotective components in Arabidopsis thaliana. Bioinformatic analysis of the cry1 regulon revealed the putative cis-element CryR1 (GnTCKAG), and here we demonstrate an interaction between CryR1 and the zinc finger GATA-type transcription factors ZINC FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM LIKE1 (ZML1) and ZML2. The ZML proteins specifically bind to the CryR1 cis-element as demonstrated in vitro and in vivo, and TCTAG was shown to constitute the core sequence required for ZML2 binding. In addition, ZML2 activated transcription of the yellow fluorescent protein reporter gene driven by the CryR1 cis-element in Arabidopsis leaf protoplasts. T-DNA insertion lines for ZML2 and its homolog ZML1 demonstrated misregulation of several cry1-dependent genes in response to excess light. Furthermore, the zml1 and zml2 T-DNA insertion lines displayed a high irradiance-sensitive phenotype with significant photoinactivation of photosystem II (PSII), indicated by reduced maximum quantum efficiency of PSII, and severe photobleaching. Thus, we identified the ZML2 and ZML1 GATA transcription factors as two essential components of the cry1-mediated photoprotective response.
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, S-901 87 Umea, Sweden.
Jehad
J
Shaikhali
Juan
J
de Dios Barajas-Lopéz
Krisztina
K
Ötvös
Dmitry
D
Kremnev
Ana Sánchez
AS
Garcia
Vaibhav
V
Srivastava
Gunnar
G
Wingsle
Laszlo
L
Bako
Åsa
Å
Strand
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D056931:Cryptochromes / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D050980:GATA Transcription Factors / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D056626:Inflorescence / Q000235:genetics / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects; D008027:Light; D018519:Meristem / Q000235:genetics / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects; D008958:Models, Molecular; D016254:Mutagenesis, Insertional; D010641:Phenotype; D045332:Photosystem II Protein Complex / Q000502:physiology; D025941:Protein Interaction Mapping; D055503:Protein Multimerization; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D018085:Regulon / Q000235:genetics; D020218:Response Elements / Q000235:genetics; D036226:Seedlings / Q000235:genetics / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D004268:DNA-Binding Proteins; D050980:GATA Transcription Factors; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C578310:ZML1 protein, Arabidopsis; C578311:ZML2 protein, Arabidopsis