Defining the minimal interacting regions of the tight junction protein MAGI-1 and HPV16 E6 oncoprotein for solution structure studies

The oncoprotein E6 produced by tumorigenic high-risk genital human papillomaviruses targets a number of cellular proteins containing PDZ domains for proteasome-mediated degradation. In particular, E6 targets the tight junction protein MAGI-1 by binding to its PDZ1 domain. Using light scattering and NMR, we explored different fragments of both the HPV16 E6 and the MAGI-1 PDZ1 domain to define the best-behaving complex for solution structure studies. We showed that the 70-residue HPV16 E6 C-terminal domain (E6C) can be efficiently substituted by a peptide spanning the 11 C-terminal residues of E6. The construct of MAGI-1 PDZ1 best suited for solution structure analysis presents a 14-residue N-terminal extension and a 26-residue C-terminal extension as compared to the construct used for the recently solved X-ray structure of a MAGI-1 PDZ1/HPV18 E6 complex. These data suggest a stabilizing role for the interdomain linker regions which separate the PDZ1 domain from its neighboring domains.