Single amino acid residue within an arginine-rich motif specifies transcription versus translation function of the Bicoid homeodomain

NIESSING D,; DRIEVER W,; SPRENGER F,; TAUBERT H,; JÄCKLE H,; RIVERA POMAR R

Molecular Cell

Lugar: Estados Unidos; Año: 2000 vol. 5 p. 395 - 401

1097-2765

Bicoid (BCD), the anterior determinant of Drosophila, controls embryonic gene expression by transcriptional activation and translational repression. Both functions require the homeodomain (HD), which recognizes DNA motifs at target gene enhancers and a specific sequence interval in the 3´ untranslated region of caudal (cad) mRNA. Here we show that the BCD HD is a nucleic acid-binding unit. Its helix III contains an arginine-rich motif (ARM), similar to the RNA-binding domain of the HIV-1 protein REV, needed for both RNA and DNA recognition. Replacement of arginine 54, within this motif, alters the RNA but not the DNA binding properties of the HD. Corresponding BCD mutants fail to repress cad mRNA translation, whereas the transcriptional target genes are still activated.