The an11 locus controlling flower pigmentation in petunia encodes a novel WD-repeat protein conserved in yeast, plants, and animals.
In petunia flowers, the loci an1, an2, and an11 control the pigmentation of the flower by stimulating the transcription of anthocyanin biosynthetic genes. The an1 and an2 locus were recently cloned and encode a basic helix-loop-helix (bHLH) and MYB-domain transcriptional activator, respectively. Here, we report the isolation of the an11 locus by transposon tagging. RNA gel blot experiments show that an11 is expressed independently from an1 and an2 throughout plant development, as well as in tissues that do not express the anthocyanin pathway. It encodes a novel WD-repeat protein that is highly conserved even in species that do not produce anthocyanins such as yeast, nematodes, and mammals. The observation that the human an11 homolog partially complements the an11 petunia mutant in transient assays shows that sequence similarity reflects functional conservation. Overexpression of an2 in an11- petals restored the activity of a structural anthocyanin gene in transient assays, indicating that AN11 acts upstream of AN2. Cell fractionation experiments show that the bulk of the AN11 protein is localized in the cytoplasm. Taken together, this indicates that AN11 is a cytoplasmic component of a conserved signal transduction cascade that modulates AN2 function in petunia, thereby linking cellular signals with transcriptional activation.
de Vetten
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Department of Genetics, Institute for Molecular Biological Sciences, Vrije Universiteit, BioCentrum Amsterdam, The Netherlands.
Quattrocchio
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Mol
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J
Koes
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R
D000595:Amino Acid Sequence; D000818:Animals; D000872:Anthocyanins / Q000096:biosynthesis*; D001483:Base Sequence; D002451:Cell Compartmentation; D017124:Conserved Sequence; D003600:Cytosol / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D017343:Genes, Plant; D005809:Genes, Regulator; D006801:Humans; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010858:Pigmentation / Q000235:genetics; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D010944:Plants / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis; D012091:Repetitive Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013997:Time Factors; D014018:Tissue Distribution
C106652:AN11 protein, Petunia x hybrida; D000872:Anthocyanins; D010940:Plant Proteins; D011994:Recombinant Proteins