Structural insights into the interaction between the Cripto CFC domain and the ALK4 receptor.
The protein Cripto is the founding member of the extra-cellular EGF-CFC growth factors, which are composed of two adjacent cysteine-rich domains: the EGF-like and the CFC. Members of the EGF-CFC family play key roles in embryonic development and are also implicated in tumourigenesis. Cripto is highly over-expressed in many tumours, while it is poorly detectable in normal tissues. Although both Cripto domains are involved in its tumourigenic activity, the CFC domain appears to play a crucial role. Indeed, through this domain, Cripto interferes with the onco-suppressive activity of Activins, either by blocking the Activin receptor ALK4 or by antagonising proteins of the TGF-beta family. We have undertaken the chemical synthesis and the structural characterisation of human CFC Cripto domain. Using a combined NMR and computational approach, supported by binding studies by SPR, we have investigated the molecular basis of the interaction between h-CFC and ALK4. Binding studies indicate that the synthetic h-CFC interacts with the ALK4 receptor with a K(D) in micro M range, whereas it does not recognise the ActRIIB receptor. The NMR study shows that the h-CFC overall topology is determined by the presence of three disulfide bridges and that residues H120 and W124 are located between the first strand and the first loop with the side chains externally exposed. A model of the CFC-ALK4 complex has also been obtained by molecular docking and shows that all residues indicated by prior mutagenesis studies can contribute to the ALK4-CFC interaction at the protein-protein interface.
Calvanese
Luisa
L
Dipartimento di Chimica, Università Federico II, Complesso Universitario MSA, via Cintia 45, 80126, Napoli, Italy.
Saporito
Angela
A
Oliva
Romina
R
D' Auria
Gabriella
G
Pedone
Carlo
C
Paolillo
Livio
L
Ruvo
Menotti
M
Marasco
Daniela
D
Falcigno
Lucia
L
D030201:Activin Receptors, Type I / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D004815:Epidermal Growth Factor / Q000737:chemistry* / Q000378:metabolism*; D058851:GPI-Linked Proteins; D036341:Intercellular Signaling Peptides and Proteins; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
D058851:GPI-Linked Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C070636:TDGF1 protein, human; D004815:Epidermal Growth Factor; C498932:ACVR1B protein, human; D030201:Activin Receptors, Type I