A peptide motif in Raver1 mediates splicing repression by interaction with the PTB RRM2 domain

Alexis P Rideau¹, Clare Gooding¹, Peter J Simpson², Tom P Monie³, Mike Lorenz⁴, Stefan Hüttelmaier⁵, Robert H Singer⁶, Stephen Matthews², Stephen Curry³ & Christopher W J Smith¹

¹  Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, CB2 1GA, UK.

²  Division of Molecular Biosciences, Imperial College, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK.

³  Divisions of Molecular and Cell Biology, Imperial College, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK.

⁴  Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany.

⁵  Medical Faculty, University of Halle-Wittenberg, Heinrich-Damerow-Str. 1, 06907 Halle (Saale), Germany.

⁶  Department of Anatomy & Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.

Polypyrimidine tract–binding protein (PTB) is a regulatory splicing repressor. Raver1 acts as a PTB corepressor for splicing of -tropomyosin (Tpm1) exon 3. Here we define a minimal region of Raver1 that acts as a repressor domain when recruited to RNA. A conserved [S/G][I/L]LGxxP motif is essential for splicing repressor activity and sufficient for interaction with PTB. An adjacent proline-rich region is also essential for repressor activity but not for PTB interaction. NMR analysis shows that LLGxxP peptides interact with a hydrophobic groove on the dorsal surface of the RRM2 domain of PTB, which constitutes part of the minimal repressor region of PTB. The requirement for the PTB-Raver1 interaction that we have characterized may serve to bring the additional repressor regions of both proteins into a configuration that allows them to synergistically effect exon skipping.

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