Recognition of distinct RNA motifs by the clustered CCCH zinc fingers of neuronal protein Unkempt.
Publication Type:Journal Article
Source:Nat Struct Mol Biol, Volume 23, Issue 1, p.16-23 (2016)
Keywords:Animals, Carrier Proteins, Crystallography, X-Ray, Mice, Models, Molecular, Nucleotide Motifs, Protein Binding, Protein Conformation, RNA, RNA-Binding Proteins, Zinc Fingers
<p>Unkempt is an evolutionarily conserved RNA-binding protein that regulates translation of its target genes and is required for the establishment of the early bipolar neuronal morphology. Here we determined the X-ray crystal structure of mouse Unkempt and show that its six CCCH zinc fingers (ZnFs) form two compact clusters, ZnF1-3 and ZnF4-6, that recognize distinct trinucleotide RNA substrates. Both ZnF clusters adopt a similar overall topology and use distinct recognition principles to target specific RNA sequences. Structure-guided point mutations reduce the RNA binding affinity of Unkempt both in vitro and in vivo, ablate Unkempt's translational control and impair the ability of Unkempt to induce a bipolar cellular morphology. Our study unravels a new mode of RNA sequence recognition by clusters of CCCH ZnFs that is critical for post-transcriptional control of neuronal morphology.</p>