Linear motifs and a linker with multiple properties determine displacement ability on a multisite intrinsically disordered viral oncoprotein

DE PRAT-GAY, GONZALO; BORCHERDS, WADE; DAUGHDRILL, GARY; GLAVINA, JULIANA; DAUGHDRILL, GARY; GLAVINA, JULIANA; CHEMES, LUCIA B; SÁNCHEZ, IGNACIO E.; GONZÁLEZ FOUTEL, NICOLAS SEBASTIAN; CHEMES, LUCIA B; SÁNCHEZ, IGNACIO E.; GONZÁLEZ FOUTEL, NICOLAS SEBASTIAN; DE PRAT-GAY, GONZALO; BORCHERDS, WADE

Castellón

Congreso; 6th International Iberian Biophysics Congress and X Iberoamerican Congress of Biophysics.; 2018

Universidad Jaume I

In this work we explored the biophysical basis for virus- host protein-protein interactions by studying the interaction between the human Adenovirus E1A protein (AdE1A) and the Retinoblastoma tumor suppressor protein (Rb). This interaction is mediated by two highly conserved linear motifs within AdE1A (E2F-like and LxCxE motifs), which are separated by a 70-residue "linker". AdE1A is an intrinsically disordered monomer with extended hydrodynamic radius (Far UV-CD, SEC-SLS). Interaction assays show that AdE1A binds to Rb with 1:1 stoichiometry and an affinity KD = 24 pM, accompanied by its strong compaction during complex formation. In addition, even though the individual sites bind Rb with lower affinity (KD = 110nM) than the cellular E2F counterpart (KD = 12 nM), modeling the system as an arrangement of two binding motifs joined by a disordered linker could explain global affinity and the effectiveness of the AdE1A protein in E2F displacement. NMR experiments confirmed AdE1A binds Rb through the residues in the E2F-like and LxCxE motifs, -which are modulated by flanking residues with complementary function in the interaction- and also through residues in the linker (TAZ2 binding region), indicating this linker acts as an entropic chain but also establishes a new set of interactions with Rb.