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Nuclear import and DNA binding of human papillomavirus type 45 L1 capsid protein
Author(s) -
Nelson Lisa M.,
Rose Robert C.,
LeRoux Lucia,
Lane Christophore,
Bruya Kate,
Moroianu Jua
Publication year - 2000
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/1097-4644(20001101)79:2<225::aid-jcb60>3.0.co;2-a
Subject(s) - karyopherin , nuclear transport , capsomere , capsid , nuclear localization sequence , biology , virology , ran , microbiology and biotechnology , cell nucleus , nucleus , virus
During the life cycle of human papillomaviruses (HPVs), the L1 capsid proteins seem to enter the nucleus twice: once after the virions infect the cells, and later during the productive phase when they assemble the replicated HPV genomic DNA into infectious virions. We established for the high‐risk HPV45 that when digitonin‐permeabilized HeLa cells were incubated with L1 homopentameric capsomers, the HPV45 L1 protein was imported into the nucleus in a receptor‐mediated manner. In contrast, intact capsids were not able to enter the nucleus. Immunoisolation assays showed that HPV45 L1 capsomers interact with cytosolic karyopherin α2β1 heterodimers. HPV45 L1 bound strongly to karyopherin α2, and weakly to karyopherin β1, as did its nuclear localization signal (NLS). Nuclear import of HPV45 L1, or of a GST‐NLS HPV45L1 fusion protein was efficiently mediated by karyopherin α2β1 heterodimers, and only weakly by karyopherin β1. Nuclear import required RanGDP, but was independent of GTP hydrolysis by Ran. Together, these data suggest that the major nuclear import pathway for HPV45 L1 major capsid protein in infected host cells is mediated by karyopherin α2β1 heterodimers and that GTP hydrolysis by Ran is not required for import. Remarkably, HPV45 L1 capsomers can interact nonspecifically with different types of HPV‐DNA, and the DNA binding region of HPV45 L1 overlaps with its NLS sequence. J. Cell. Biochem. 79:225–238, 2000. © 2000 Wiley‐Liss, Inc.