| Function |
Human papillomaviruses, particularly type 16 (designated HPV16), infect the
genital tract and may lead to cervical cancer. Protection against HPV16 is
thought to be provided by neutralizing antibodies directed to the major caspid
protein L1 of HPV16. HPV16 L1 forms the pentameric assembly unit of the viral
shell, and the binding of HPV16 L1 to the cell surface without the involvement
of minor capsid protein L2 is believed to be the first step of HPV16 infection.
The L1-binding domain located near the C-terminus of L2 binds L1 prior to
completion of capsid assembly and is required for efficient encapsidation of
the viral genome. In addition, the C-terminus of L1 is necessary for both DNA
binding and DNA packaging. Expression of the late gene L1 is restricted to the
upper layers of the infected epithelium. HPV16 L1 is able to package unrelated
plasmid DNA in vitro and deliver the foreign DNA to eukaryotic cells with
the subsequent expression of the encoded gene. L1 shows a diffuse nuclear
distribution whereas L2 is localized to punctate nuclear regions identified as
pro-monocytic leukemia protein oncogenic domains (PODs). Coexpression of
L1 and L2 induces a relocalization of L1 into the PODs. |
