title: The high risk HPV16 L2 minor capsid protein has multiple transport signals that mediate its nucleocytoplasmic traffic.
abstract: In this study we examined the transport signals contributing to HPV16 L2 nucleocytoplasmic traffic using confocal microscopy analysis of enhanced green fluorescent protein-L2 (EGFP-L2) fusions expressed in HeLa cells. We confirmed that both nuclear localization signals (NLSs), the nNLS (1MRHKRSAKRTKR12) and cNLS (456RKRRKR461), previously characterized in vitro (Darshan et al., 2004), function independently in vivo. We discovered that a middle region rich in arginine residues (296SRRTGIRYSRIGNKQTLRTRS316) functions as a nuclear retention sequence (NRS), as mutagenesis of critical arginine residues within this NRS reduced the fraction of L2 in the nucleus despite the presence of both NLSs. Significantly, the infectivity of HPV16 pseudoviruses containing either RR297AA or RR297EE within the L2 NRS was strongly reduced both in HaCaT cells and in a murine challenge model. Experiments using Ratjadone A nuclear export inhibitor and mutation-localization analysis lead to the discovery of a leucine-rich nuclear export signal ((462)LPYFFSDVSL) mediating 16L2 nuclear export. These data indicate that HPV16 L2 nucleocytoplasmic traffic is dependent on multiple functional transport signals.
authors.affiliation: Biology Department, Boston College, Chestnut Hill, MA 02467, USA.
authors.forename: Shahan
authors.initials: S
authors.lastname: Mamoor
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Onder
authors.forename: Balasubramanyam
authors.initials: B
authors.lastname: Karanam
authors.forename: Kihyuck
authors.initials: K
authors.lastname: Kwak
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bordeaux
authors.forename: Lauren
authors.initials: L
authors.lastname: Crosby
authors.forename: Richard B S
authors.initials: RB
authors.lastname: Roden
authors.forename: Junona
authors.initials: J
authors.lastname: Moroianu
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D036022:Capsid Proteins / Q000378:metabolism*; D002460:Cell Line; D005260:Female; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D052162:Human papillomavirus 16 / Q000378:metabolism*; D006801:Humans; D008156:Luciferases; D051379:Mice; D008807:Mice, Inbred BALB C; D021381:Protein Transport / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D036022:Capsid Proteins; D008156:Luciferases