Structural Analysis Of Large Protein Complexes Involving Hpv E6 Oncoproteins.
Reference : PhD Gilles Travé
Offer publication : Jan. 26, 2018
Human Papilloma Viruses (HPVs) infect epithelia (skin or musosa) where they induce cell proliferations supporting viral replication. "High-risk" mucosal HPV (hrm-HPV) cause 95% of cervical cancers ("cancer du col de l'utérus") and 60% of oropharyngeal cancers. The E6 oncoprotein, essential for HPV-induced oncogenesis, recruits numerous host proteins that vary for each HPV considered. For instance, hrm-HPV E6 proteins forms a trimer with E6AP (a 850-residue ubiquitin ligase and transcriptional co-activator) and tumor suppressor p53 (393 residues). This results in ubiquitin-mediated degradation of p53, favoring the uprise of cancer. Some hrm-HPV E6 proteins also bind to IRF3, a transcription factor involved in the interferon innate antiviral response. On the other hand, most cutaneous HPV E6 proteins recruit MAML1, a transcription factor of the Notch cell differentiation pathway. E6 from a cutaneous HPV species associated with skin cancers recruits the CBP-p300 acetyl transferase (~2500 residues), a general transcriptional co-activator essential for the innate antiviral response, whereas E6 from another cutaneous HPV species bind to the multiprotein Ccr4-Not complex implicated in mRNA metabolism. Remarkably, most E6 targets are studied by other IGBMC teams, probably due to their general link to transcription.
Our team has solved structures of diverse E6 proteins bound to peptides and domains derived from various host proteins: focal adhesion paxillin (Zanier et al., Science 2013), E6AP and p53 (Zanier et al., Science 2013, Martinez et al., Nature 2016), MAGI-1 (Charbonnier et al., JMB 2011), IRF3 and MAML1 (Suarez & Cousido-Siah, unpublished data). While these structures described E6-target interfaces, they comprised only fragments of E6 targets, so that the mechanisms induced by E6 binding (conformational changes, alteration of enzymatic activities, etc...) remain largely unknown.
The proposed PhD project will thus consist of preparing full-length E6-binding proteins and integral E6-binding multiprotein complexes, and analyzing their interaction with E6 proteins by means of a combination of Cryo-Electron Microscopy and Crystallography. We will particularly focus on E6 proteins complexed with full-length E6AP and p53, with the CBP-p300 transcriptional activator and the Ccr4-Not complex.
Application Deadline : Nov. 1, 2018