Characterization of the nuclear localization signal of high risk HPV16 E2 protein.
The E2 protein of high risk human papillomavirus type 16 (HPV16) contains an amino-terminal (N) domain, a hinge (H) region and a carboxyl-terminal (C) DNA-binding domain. Using enhanced green fluorescent protein (EGFP) fusions with full length E2 and E2 domains in transfection assays in HeLa cells, we found that the C domain is responsible for the nuclear localization of E2 in vivo, whereas the N and H domains do not contain additional nuclear localization signals (NLSs). Deletion analysis of EGFP-E2 and EGFP-cE2 determined that the C domain contains an alpha helix cNLS that overlaps with the DNA-binding region. Mutational analysis revealed that the arginine and lysine residues in this cNLS are essential for nuclear localization of HPV16 E2. Interestingly, these basic amino acid residues are well conserved among the E2 proteins of BPV-1 and some high risk HPV types but not in the low risk HPV types, suggesting that there are differences between the NLSs and corresponding nuclear import pathways between these E2 proteins.
Klucevsek
Kristin
K
Biology Department, Boston College, Higgins Hall, room 578, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA.
Wertz
Mary
M
Lucchi
John
J
Leszczynski
Anna
A
Moroianu
Junona
J
D000818:Animals; D001120:Arginine / Q000502:physiology; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D052162:Human papillomavirus 16 / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000502:physiology; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism*; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D017434:Protein Structure, Tertiary
D004268:DNA-Binding Proteins; C054855:E2 protein, Human papillomavirus type 16; D019913:Nuclear Localization Signals; D009856:Oncogene Proteins, Viral; D001120:Arginine; D008239:Lysine