Determinants of RNA binding and translational repression by the Bicaudal-C regulatory protein.
Bicaudal-C (Bic-C) RNA binding proteins function as important translational repressors in multiple biological contexts within metazoans. However, their RNA binding sites are unknown. We recently demonstrated that Bic-C functions in spatially regulated translational repression of the xCR1 mRNA during Xenopus development. This repression contributes to normal development by confining the xCR1 protein, a regulator of key signaling pathways, to specific cells of the embryo. In this report, we combined biochemical approaches with in vivo mRNA reporter assays to define the minimal Bic-C target site within the xCR1 mRNA. This 32-nucleotide Bic-C target site is predicted to fold into a stem-loop secondary structure. Mutational analyses provided evidence that this stem-loop structure is important for Bic-C binding. The Bic-C target site was sufficient for Bic-C mediated repression in vivo. Thus, we describe the first RNA binding site for a Bic-C protein. This identification provides an important step toward understanding the mechanisms by which evolutionarily conserved Bic-C proteins control cellular function in metazoans.
From the Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53706.
Yan
Y
Zhang
Sookhee
S
Park
Susanne
S
Blaser
Michael D
MD
Sheets
D020413:3' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D018507:Gene Expression Regulation, Developmental; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D014176:Protein Biosynthesis; D012313:RNA / Q000737:chemistry*; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012260:Ribonucleases / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
D020413:3' Untranslated Regions; C453440:BICC1 protein, Xenopus; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029867:Xenopus Proteins; D012313:RNA; D008156:Luciferases; D012260:Ribonucleases
Development; Kidney; Maternal mRNA; RNA Binding Protein; RNA Silencing; Transforming Growth Factor Beta (TGFbeta); Translation Regulation; Xenopus; mRNA