title: Structurally related Arabidopsis ANGUSTIFOLIA is functionally distinct from the transcriptional corepressor CtBP.
abstract: ANGUSTIFOLIA (AN) controls leaf morphology in the plant Arabidopsis thaliana. Previous studies on sequence similarity demonstrated that the closest proteins to AN are members of animal C-terminal-binding proteins (CtBPs) found in nematodes, arthropods, and vertebrates. Drosophila CtBP (dCtBP) functions as a transcriptional corepressor for deoxyribonucleic acid (DNA)-binding repressors containing the short amino acid motif, PXDLS, to regulate tissue specification and segmentation during early embryogenesis. It has previously been shown that AN was thought to repress transcription similar to the function of CtBPs; however, AN lacks some of the structural features that are conserved in animal CtBPs. In this paper, we examined whether AN is functionally related to dCtBP. Firstly, we re-examined sequence similarity among AN and various CtBPs from several representative species in the plant and animal kingdoms. Secondly, yeast two-hybrid assays demonstrated that AN failed to interact with an authentic CtBP-interacting factor, adenovirus E1A oncoprotein bearing the PXDLS motif. Thirdly, AN tethered to DNA was unable to repress the expression of reporter genes in transgenic Drosophila embryos. Fourthly, overexpression assays suggested that dCtBP and AN function differently in Drosophila tissues. Finally, AN failed to rescue the zygotic lethality caused by dCtBP loss-of-function. These data, taken together, suggest that AN is functionally distinct from dCtBP. Likely, ancestral CtBPs acquired corepressor function (capability of both repression and binding to repressors containing the PXDLS motif) after the animal-plant divergence but before the protostome-deuterostome split. We therefore propose to categorize AN as a subfamily member within the CtBP/BARS/RIBEYE/AN superfamily.
authors.affiliation: Department of Cell and Developmental Biology, Weill Medical College of Cornell University, 1300 York Avenue, Box 60, New York, NY 10021, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Stern
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Aihara
authors.forename: Kiu-Hyung
authors.initials: KH
authors.lastname: Cho
authors.forename: Gyung-Tae
authors.initials: GT
authors.lastname: Kim
authors.forename: Gorou
authors.initials: G
authors.lastname: Horiguchi
authors.forename: Giorgio A
authors.initials: GA
authors.lastname: Roccaro
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Guevara
authors.forename: Huan Huan
authors.initials: HH
authors.lastname: Sun
authors.forename: Dereje
authors.initials: D
authors.lastname: Negeri
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsukaya
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nibu
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D019143:Evolution, Molecular; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D010641:Phenotype; D011485:Protein Binding; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D040681:Structural Homology, Protein; D019076:Transgenes; D015053:Zygote / Q000378:metabolism
chemical_list: D000429:Alcohol Oxidoreductases; D029681:Arabidopsis Proteins; D004247:DNA; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C452846:DETORQEO protein, Arabidopsis; C096794:C-terminal binding protein