The L1 major capsid protein of human papillomavirus type 11 interacts with Kap beta2 and Kap beta3 nuclear import receptors.

We have previously shown that the L1 major capsid protein of low-risk HPV11 binds to the Kap alpha2 adapter and enters the nucleus via a Kap alpha2beta1-mediated pathway. In this study, we discovered that HPV11 L1 capsomeres bind to Kap beta2 import receptor, known to mediate nuclear import of hnRNP A1 via interaction with its nuclear localization signal termed M9. Significantly, binding of HPV11 L1 capsomeres to Kap beta2 inhibited the nuclear import of Kap beta2, and its specific M9-containing cargo. Interestingly, HPV11 L1 capsomeres also interacted with Kap beta3 import receptor and inhibited Kap beta3 nuclear import. Moreover, the L1 capsomeres of high-risk HPV-16 shared these activities. These data suggest that HPV L1 major capsid proteins interact with Kap beta2 and Kap beta3, and they may inhibit the Kap beta2- and Kap beta3-mediated nuclear import pathways during the productive phase of the viral life cycle when the virions are assembled and released.