Question

Human papillomavirus can cause cervical cancer. The virus encodes E6, a protein that binds p53. Based on this fact and what you know about p53, what effect do you think E6 binding has on p53 activity?

a) Activation
b) Inhibition
c) Deletion
d) Duplication

Answer 1

The HPV E6 protein binds to and marks the tumor suppressor protein p53 for degradation, disrupting its normal function of DNA damage response and apoptosis, thereby contributing to the uncontrolled cell growth and accumulation of mutations characteristic of cancer.

Step-by-step explanation:

Human papillomavirus (HPV) is known to be a significant risk factor for the development of cervical cancer. One of the ways HPV contributes to cancer progression is through the action of its encoded E6 protein. E6 has a crucial interaction with the host cell's p53 protein, which is a tumor suppressor gene product responsible for halting the cell cycle or initiating apoptosis in response to DNA damage.

p53's role in preventing cancer is critical; it acts as a safeguard, preventing cells with damaged DNA from dividing, and initiating apoptosis to remove potentially dangerous cells. Hence, binding of E6 to p53 would not activate or protect p53, nor does it directly mutate the protein. Instead, E6 binding marks p53 for degradation, effectively neutralizing this checkpoint and allowing the cell to divide without control or repair, contributing to cancer development.

The correct answer to the effect of E6 binding on p53 activity is therefore 'd. E6 binding marks p53 for degradation'. This mechanism allows for the accumulation of mutations and uncontrolled cell growth, key characteristics of cancer cells.