Unraveling the key molecular determinants in the interaction between the Retinoblastoma Tumour Suppressor Protein and Short Linear Motifs.

GONZALEZ FOUTEL, NICOLÁS; GIBSON, TOBY; ÁLVAREZ, LUCÍA; WILL, DAVID; CLARON, MICHAEL; CHEMES, LUCÍA

Seefeld in Tirol

Congreso; Modularity of signaling proteins and networks; 2019

EMBO

The human pocket protein retinoblastoma (pRb) acts as potent tumour suppressor by negative regulation of the eukaryotic cell cycle. Multiple oncogenic viruses have evolved to inactivate pRb using protein sub-sequences called Short Linear Motifs (SLiMs). SLiMs play a central role in cellular signaling by regulating protein-protein interactions. In particular, the LxCxE motif has been reported in at least 30 cellular pRb interactors and in multiple viral proteins that hijack the pRb network. Recent studies from our group suggest that the interactions between the viral proteins and pRb have specific features that distinguish them from endogenous cellular interactions, having evolved higher affinities that result in effective competition with host interactions. The main cellular interactions mediated by LxCxE motifs and their pocket protein specificity remain to be identified.The aim of this work is to understand the molecular mechanism by which viral SLiMS manage to displace the endogenous Rb-SLiM complexes, providing key insights into the evolution of pRb interactions. For this purpose, we designed peptides that contain different mutations in the conserved region of the LxCxE motif at interacting and non-interacting positions. For each RbAB-SLiM complex we obtained the equilibrium affinity constant by means of spectroscopic techniques, and the different association and dissociation reactions were monitored using FITC-labelled peptides and Stopped Flow spectroscopy.