Structurally related Arabidopsis ANGUSTIFOLIA is functionally distinct from the transcriptional corepressor CtBP.
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.
Stern
Mark D
MD
Department of Cell and Developmental Biology, Weill Medical College of Cornell University, 1300 York Avenue, Box 60, New York, NY 10021, USA.
Aihara
Hitoshi
H
Cho
Kiu-Hyung
KH
Kim
Gyung-Tae
GT
Horiguchi
Gorou
G
Roccaro
Giorgio A
GA
Guevara
Elizabeth
E
Sun
Huan Huan
HH
Negeri
Dereje
D
Tsukaya
Hirokazu
H
Nibu
Yutaka
Y
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
D000429:Alcohol Oxidoreductases; D029681:Arabidopsis Proteins; D004247:DNA; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C452846:DETORQEO protein, Arabidopsis; C096794:C-terminal binding protein