Final answer:
The E6 protein from HPV inactivates p53 by ubiquitination, which signals for its degradation by the proteasome, eliminating its tumor-suppressing activities and allowing unregulated cell division.
Step-by-step explanation:
The E6 protein from the Human papillomavirus (HPV) leads to the degradation of the p53 protein by the proteasome. This is the correct option from the provided choices. Normally, p53 works as a tumor suppressor gene product by detecting DNA damage and either pausing the cell cycle for repair or initiating apoptosis. E6 protein binds to p53, rendering it inactive; this is done through ubiquitin-mediated degradation.
The ubiquitin-proteasomal pathway involves ubiquitin-activating enzyme (E1), ubiquitin-conjugating enzyme (E2), and ubiquitin ligases (E3), with E3 controlling the specificity of protein degradation. Here, E6 acts as an adaptor, recruiting E6-associated protein (E6-AP), an ubiquitin ligase, to p53, which leads to its ubiquitination and consequent degradation by the proteasome.