Discrete Domains Mediate the Light-Responsive Nuclear and Cytoplasmic Localization of Arabidopsis COP1

Stacey, Minviluz G.; Hicks, Stephanie; Arnim, Albrecht G. von

doi:10.2307/3870865

Cited by 14 publications

(41 citation statements)

References 20 publications

(25 reference statements)

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“…Besides regulation of intercellular movement, TF activity might also be regulated via modulation of subcellular localization, as has been previously reported in plants (34,35) and animals (12, 13). For 10 of the 39 (25%) translational fusions that had detectable GFP, the GFP-fusion protein was not found to be nuclear-localized in any of the root tissues (Table 3).…”

Section: Transcription Factor Localization Can Be Affected By Sequencmentioning

confidence: 89%

Transcriptional and posttranscriptional regulation of transcription factor expression in Arabidopsis roots

Lee

Colinas²,

Wang³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

259

296

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Understanding how the expression of transcription factor (TF) genes is modulated is essential for reconstructing gene regulatory networks. There is increasing evidence that sequences other than upstream noncoding can contribute to modulating gene expression, but how frequently they do so remains unclear. Here, we investigated the regulation of TFs expressed in a tissue-enriched manner in Arabidopsis roots. For 61 TFs, we created GFP reporter constructs driven by each TF's upstream noncoding sequence (including the 5 UTR) fused to the GFP reporter gene alone or together with the TF's coding sequence. We compared the visually detectable GFP patterns with endogenous mRNA expression patterns, as defined by a genome-wide microarray root expression map. An automated image analysis method for quantifying GFP signals in different tissues was developed and used to validate our visual comparison method. From these combined analyses, we found that (i) the upstream noncoding sequence was sufficient to recapitulate the mRNA expression pattern for 80% (35͞44) of the TFs, and (ii) 25% of the TFs undergo posttranscriptional regulation via microRNA-mediated mRNA degradation (2͞24) or via intercellular protein movement (6͞24). The results suggest that, for Arabidopsis TFs, upstream noncoding sequences are major contributors to mRNA expression pattern establishment, but modulation of transcription factor protein expression pattern after transcription is relatively frequent. This study provides a systematic overview of regulation of TF expression at a cellular level. intercellular protein movement ͉ intergenic ͉ microRNA-mediated mRNA degradation ͉ transcriptional regulation

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Section: Transcription Factor Localization Can Be Affected By Sequencmentioning

confidence: 89%

Transcriptional and posttranscriptional regulation of transcription factor expression in Arabidopsis roots

Lee

Colinas²,

Wang³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

259

296

View full text Add to dashboard Cite

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“…Insertions of COP1 fragments in between GFP and the NIa protein from tobacco etch virus (27) were made by amplification of subfragments from a COP1 cDNA using anchored polymerase chain reaction and cloning of the fragments to pRTL2-GFP-NIa (13). The fusions lacking the NIa cDNA have been described previously (12). The structures of proteins expressed from COP1 mutant alleles are diagrammed in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Transient Assay-Fusion proteins were expressed using particle gun-mediated DNA delivery in onion epidermal cells (12) and imaged by epifluorescence microscopy with a MicroMax CCD camera (Princeton Instruments (12,13)). The position of the nucleus and the nucleoli was confirmed under bright-field illumination.…”

Section: Methodsmentioning

confidence: 99%

“…The redistribution of the ␤-glucuronidase-COP1 protein by light is mediated by multiple photoreceptors of the phytochrome and cryptochrome families (11). Cytoplasmic localization of COP1 is mediated by a cytoplasmic localization signal (CLS), 1 which counteracts a classical bipartite nuclear localization signal (NLS), located in the central core domain, in a light-dependent manner (12).…”

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confidence: 99%

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A Novel Motif Mediates the Targeting of the Arabidopsis COP1 Protein to Subnuclear Foci

Stacey

Arnim

1999

Journal of Biological Chemistry

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The constitutive photomorphogenesis 1 (COP1) protein of Arabidopsis thaliana accumulates in discrete subnuclear foci. To better understand the role of subnuclear architecture in COP1-mediated gene expression, we investigated the structural motifs of COP1 that mediate its localization to subnuclear foci using mutational analysis with green fluorescent protein as a reporter. In a transient expression assay, a subnuclear localization signal consisting of 58 residues between amino acids 120 and 177 of COP1 was able to confer speckled localization onto the heterologous nuclear NIa protein from tobacco etch virus. The subnuclear localization signal overlaps two previously characterized motifs, a cytoplasmic localization signal and a putative ␣-helical coiled-coil domain that has been implicated in COP1 dimerization. Moreover, phenotypically lethal mutations in the carboxyl-terminal WD-40 repeats inhibited localization to subnuclear foci, consistent with a functional role for the accumulation of COP1 at subnuclear sites.

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“…Our functional dissection of the COP1 protein implied a supportive role for the COP1 RING finger in self-association and light-responsive nucleocytoplasmic partition (11,33). Considering the fact that the RING finger motif of COP1 is a specific protein-protein interactive motif for RING-H2 motif of CIP8, it may achieve a functional role by its interaction with target proteins, such as CIP8.…”

Section: Discussionmentioning

confidence: 87%

The RING Finger Motif of Photomorphogenic Repressor COP1 Specifically Interacts with the RING-H2 Motif of a NovelArabidopsis Protein

Torii¹,

Stoop²,

Okamoto³

et al. 1999

Journal of Biological Chemistry

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The constitutive photomorphogenic 1 (COP1) protein of Arabidopsis functions as a molecular switch for the seedling developmental fates: photomorphogenesis under light conditions and skotomorphogenesis in darkness. The COP1 protein contains a cysteine-rich zincbinding RING finger motif found in diverse groups of regulatory proteins. To understand the role of the COP1 RING finger in mediating protein-protein interaction, we have performed a yeast two-hybrid screen and isolated a novel protein with a RING-H2 motif, a variant type of the RING finger. This protein, designated COP1 Interacting Protein 8 (CIP8), is encoded by a single copy gene and localized to cytosol in a transient assay. In addition to the RING-H2 motif, the predicted protein has a C4 zinc finger, an acidic region, a glycine-rich cluster, and a serine-rich cluster. The COP1 RING finger and the CIP8 RING-H2 domains are sufficient for their interaction with each other both in vitro and in yeast, whereas neither motif displayed significant self-association. Moreover, site-directed mutagenesis studies demonstrated that the expected zinc-binding ligands of the RING finger and RING-H2 fingers are essential for their interaction. Our findings indicate that the RING finger motif, in this case, serves as autonomous protein-protein interaction domain. The allele specific effect of cop1 mutations on the CIP8 protein accumulation in seedlings indicates that its stability in vivo is dependent on the COP1 protein.Zinc ions provide structural integrity to many regulatory proteins, most often through cysteine and histidine ligands that form a tetrahedral geometry. The RING finger motif is a cysteine-rich zinc-binding domain defined by the consensus sequence: CX 2 CX (9 -39) CX (1-3) HX (2-3) CX 2 CX (4 -48) CX 2 C (C 3 HC 4 ). A unique feature of this motif is that the consensus residues coordinate two zinc ions in a "cross-braced" fashion (1, 2). Thus, the RING finger forms one integrated structural unit, rather than forming two tandem zinc finger modules. Proteins containing RING finger domains are found in viruses and all eukaryotes, including yeast, plants, and animals. They have diverse cellular functions, including oncogenesis, viral gene expression, signal transduction, peroxisome biogenesis, DNA repair and recombination, and membrane vesicle sorting (2). The RING finger motif has been shown in many cases to play a role in mediating protein-protein interactions. However, the precise role of the RING finger, as well as specific interactive target motifs of the RING finger, have yet to be clearly defined.The Arabidopsis COP1 1 protein serves as a repressor of photomorphogenesis. In the dark, the COP1 protein localizes to the nucleus and represses photomorphogenesis by inhibiting transcription factors that promote light-inducible gene expression (3-5). Light stimuli abrogate the nuclear localization of COP1 and allows seedlings to pursue photomorphogenic development (6). COP1 contains an N-terminal RING finger motif (7,8), which has been demonstrated to bind tw...

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Discrete Domains Mediate the Light-Responsive Nuclear and Cytoplasmic Localization of Arabidopsis COP1

Cited by 14 publications

References 20 publications

Transcriptional and posttranscriptional regulation of transcription factor expression in Arabidopsis roots

Transcriptional and posttranscriptional regulation of transcription factor expression in Arabidopsis roots

A Novel Motif Mediates the Targeting of the Arabidopsis COP1 Protein to Subnuclear Foci

The RING Finger Motif of Photomorphogenic Repressor COP1 Specifically Interacts with the RING-H2 Motif of a NovelArabidopsis Protein

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