Human papillomavirus type 6 E7 protein (HPV-6 E7)

Human papillomavirus type 6 E7 protein is a small phosphoprotein of approximately 100 amino acids that functions as a master regulator of cellular disruption during HPV infection[3]. It contains three conserved regions (CR1/2/3), with CR1 and CR2 showing homology to adenovirus E1A proteins and SV40 large T antigen[2]. The CR3 region at the carboxyl terminal contains a zinc-binding domain with two CXXC motifs that enable zinc-dependent dimerization and interactions with cellular proteins involved in cell cycle regulation[2]. Unlike high-risk HPV types (16, 18), HPV-6 is generally classified as a low-risk type primarily associated with genital warts rather than cancer. However, the E7 protein still plays crucial roles in the viral life cycle by driving quiescent cells into the cell cycle and stimulating progression from G1 to S phase[4]. This allows the virus to replicate its genome in cells that would otherwise be non-dividing. The protein lacks intrinsic enzymatic activity but exerts its effects by binding to and modulating host proteins, particularly tumor suppressor proteins like retinoblastoma protein (pRb)[3]. When E7 targets pRb for ubiquitination, it leads to the release of E2F transcription factors that promote cell cycle progression[2]. Additionally, E7 can bypass the mitotic checkpoint through p53-independent mechanisms, potentially by abrogating Rb function or increasing MDM2 expression[6]. While HPV-6 E7 is less oncogenic than its high-risk counterparts, understanding its structure and function remains important for developing targeted therapies against HPV infections and HPV-associated diseases.

Other names

E7 oncoproteinHPV-6a E7 proteinEarly protein 7

Binding to retinoblastoma protein (pRb)