Resonance assignment and secondary structure of the middle MA-3 domain and complete tandem MA-3 region of the tumour suppressor protein Pdcd4

Pdcd4 (Programmed Cell Death Protein 4) is a novel eukaryotic tumour suppressor protein, which is involved in the regulation of both transcription and translation (reviewed in Lankat-Buttgereit and Goke 2009). The protein contains two interacting MA-3 domains (MA-3(M) and MA-3(C)), which are linked by a short semi-flexible linker region (Waters et al. 2007; Suzuki et al. 2008). The MA-3 domains are involved in mediating specific protein-protein interactions with functional partners such as eIF4A (Yang et al. 2003 ). Here we report essentially complete backbone and side chain N-15, C-13 and H-1 assignments for a construct composed of the middle MA-3 domain and subsequent linker region (MA-3(M)) and backbone assignments for the entire tandem MA-3 region of Pdcd4 (Pdcd4 MA-3(M-C)). Analysis of the backbone chemical shift data obtained indicates that Pdcd4 MA-3(M) contains eight helical regions corresponding to over 74% of the protein backbone and that Pdcd4 MA-3(M-C) contains fifteen helical regions (72%). Comparison of the position of these helical regions with those observed in the crystal structures suggests that the solution and crystal structures of both proteins are very similar.