scholarly journals The L2 Minor Capsid Protein of Human Papillomavirus Type 16 Interacts with a Network of Nuclear Import Receptors

2004 ◽  
Vol 78 (22) ◽  
pp. 12179-12188 ◽  
Author(s):  
Medha S. Darshan ◽  
John Lucchi ◽  
Emily Harding ◽  
Junona Moroianu
Keyword(s):  
Human Papillomavirus ◽  
Nuclear Import ◽  
Capsid Proteins ◽  
Permeabilized Cells ◽  
Nuclear Localization Signals ◽  
Human Papillomavirus Type 16 ◽  
C Terminus ◽  
Binding Data ◽  
Import Receptors ◽  
Productive Phase

ABSTRACT The L2 minor capsid proteins enter the nucleus twice during viral infection: in the initial phase after virion disassembly and in the productive phase when, together with the L1 major capsid proteins, they assemble the replicated viral DNA into virions. In this study we investigated the interactions between the L2 protein of high-risk human papillomavirus type 16 (HPV16) and nuclear import receptors. We discovered that HPV16 L2 interacts directly with both Kapβ2 and Kapβ3. Moreover, binding of Ran-GTP to either Kapβ2 or Kapβ3 inhibits its interaction with L2, suggesting that the Kapβ/L2 complex is import competent. In addition, we found that L2 forms a complex with the Kapα2β1 heterodimer via interaction with the Kapα2 adapter. In agreement with the binding data, nuclear import of L2 in digitonin-permeabilized cells could be mediated by either Kapα2β1 heterodimers, Kapβ2, or Kapβ3. Mapping studies revealed that HPV16 L2 contains two nuclear localization signals (NLSs), in the N terminus (nNLS) and C terminus (cNLS), that could mediate its nuclear import. Together the data suggest that HPV16 L2 interacts via its NLSs with a network of karyopherins and can enter the nucleus via several import pathways mediated by Kapα2β1 heterodimers, Kapβ2, and Kapβ3.

scholarly journals The L2 Minor Capsid Protein of Low-Risk Human Papillomavirus Type 11 Interacts with Host Nuclear Import Receptors and Viral DNA

2006 ◽  
Vol 80 (16) ◽  
pp. 8259-8262 ◽  
Author(s):  
J. Bordeaux ◽  
S. Forte ◽  
E. Harding ◽  
M. S. Darshan ◽  
K. Klucevsek ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Low Risk ◽  
Classical Pathway ◽  
Viral Dna ◽  
Nuclear Localization Signals ◽  
C Terminus ◽  
Import Receptors

ABSTRACT Analysis of the interactions of low-risk human papillomavirus type 11 (HPV11) L2 with karyopherin β (Kap β) nuclear import receptors revealed that L2 interacted with Kap β1, Kap β2, and Kap β3 and formed a complex with the Kap α2β1 heterodimer. HPV11 L2 contains two nuclear localization signals (NLSs)—in the N terminus and the C terminus—that could mediate its nuclear import via a classical pathway. Each NLS was functional in vivo, and deletion of both of them abolished L2 nuclear localization. Both NLSs interacted with the viral DNA. Thus, HPV11 L2 can interact with several karyopherins and the viral DNA and may enter the nucleus via multiple pathways.

Detection of Class-Specific Antibodies to Baculovirus-Derived Human Papillomavirus Type 16 (HPV-16) Capsid Proteins

1994 ◽  
pp. 155-160 ◽  
Author(s):  
John Cason ◽  
Parminder K. Kambo ◽  
Bhavneet Shergill ◽  
John Bible ◽  
Barbara Kell ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Capsid Proteins ◽  
Hpv 16 ◽  
Specific Antibodies ◽  
Human Papillomavirus Type 16

scholarly journals An Atp-Dependent, Ran-Independent Mechanism for Nuclear Import of the U1a and U2b′′ Spliceosome Proteins

2000 ◽  
Vol 148 (2) ◽  
pp. 293-304 ◽  
Author(s):  
Martin Hetzer ◽  
Iain W. Mattaj
Keyword(s):  
Adenosine Triphosphate ◽  
Nuclear Import ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Fraction ◽  
Gtp Hydrolysis ◽  
Permeabilized Cells ◽  
Nuclear Localization Signals ◽  
Small Nuclear Ribonucleoprotein ◽  
Nuclear Ribonucleoprotein

Nuclear import of the two uracil-rich small nuclear ribonucleoprotein (U snRNP) components U1A and U2B′′ is mediated by unusually long and complex nuclear localization signals (NLSs). Here we investigate nuclear import of U1A and U2B′′ in vitro and demonstrate that it occurs by an active, saturable process. Several lines of evidence suggest that import of the two proteins occurs by an import mechanism different to those characterized previously. No cross competition is seen with a variety of previously studied NLSs. In contrast to import mediated by members of the importin-β family of nucleocytoplasmic transport receptors, U1A/U2B′′ import is not inhibited by either nonhydrolyzable guanosine triphosphate (GTP) analogues or by a mutant of the GTPase Ran that is incapable of GTP hydrolysis. Adenosine triphosphate is capable of supporting U1A and U2B′′ import, whereas neither nonhydrolyzable adenosine triphosphate analogues nor GTP can do so. U1A and U2B′′ import in vitro does not require the addition of soluble cytosolic proteins, but a factor or factors required for U1A and U2B′′ import remains tightly associated with the nuclear fraction of conventionally permeabilized cells. This activity can be solubilized in the presence of elevated MgCl2. These data suggest that U1A and U2B′′ import into the nucleus occurs by a hitherto uncharacterized mechanism.

scholarly journals Membrane Orientation of the Human Papillomavirus Type 16 E5 Oncoprotein

2009 ◽  
Vol 84 (4) ◽  
pp. 1696-1703 ◽  
Author(s):  
Ewa Krawczyk ◽  
Frank A. Suprynowicz ◽  
Sawali R. Sudarshan ◽  
Richard Schlegel
Keyword(s):  
Human Papillomavirus ◽  
Transmembrane Domain ◽  
Transmembrane Protein ◽  
Biologically Active ◽  
Human Papillomavirus Type 16 ◽  
Cytoplasmic Proteins ◽  
C Terminus ◽  
Low Concentrations ◽  
E5 Protein ◽  
E5 Oncoprotein

ABSTRACT The E5 protein of human papillomavirus type 16 is a small, hydrophobic protein that localizes predominantly to membranes of the endoplasmic reticulum (ER). To define the orientation of E5 in these membranes, we employed a differential, detergent permeabilization technique that makes use of the ability of low concentrations of digitonin to selectively permeabilize the plasma membrane and saponin to permeabilize all cellular membranes. We then generated a biologically active E5 protein that was epitope tagged at both its N and C termini and determined the accessibility of these termini to antibodies in the presence and absence of detergents. In both COS cells and human ectocervical cells, the C terminus of E5 was exposed to the cytoplasm, whereas the N terminus was restricted to the lumen of the ER. Finally, the deletion of the E5 third transmembrane domain (and terminal hydrophilic amino acids) resulted in a protein with its C terminus in the ER lumen. Taken together, these topology findings are compatible with a model of E5 being a 3-pass transmembrane protein and with studies demonstrating its C terminus interacting with cytoplasmic proteins.

scholarly journals Adenovirus Core Protein pVII Is Translocated into the Nucleus by Multiple Import Receptor Pathways

2006 ◽  
Vol 80 (19) ◽  
pp. 9608-9618 ◽  
Author(s):  
Harald Wodrich ◽  
Aurelia Cassany ◽  
Maximiliano A. D'Angelo ◽  
Tinglu Guan ◽  
Glen Nemerow ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Nuclear Import ◽  
Cultured Cells ◽  
Core Protein ◽  
Deletion Mapping ◽  
Nuclear Entry ◽  
Permeabilized Cells ◽  
Importin Α ◽  
Import Receptors

ABSTRACT Adenoviruses are nonenveloped viruses with an ∼36-kb double-stranded DNA genome that replicate in the nucleus. Protein VII, an abundant structural component of the adenovirus core that is strongly associated with adenovirus DNA, is imported into the nucleus contemporaneously with the adenovirus genome shortly after virus infection and may promote DNA import. In this study, we evaluated whether protein VII uses specific receptor-mediated mechanisms for import into the nucleus. We found that it contains potent nuclear localization signal (NLS) activity by transfection of cultured cells with protein VII fusion constructs and by microinjection of cells with recombinant protein VII fusions. We identified three NLS-containing regions in protein VII by deletion mapping and determined important NLS residues by site-specific mutagenesis. We found that recombinant protein VII and its NLS-containing domains strongly and specifically bind to importin α, importin β, importin 7, and transportin, which are among the most abundant cellular nuclear import receptors. Moreover, these receptors can mediate the nuclear import of protein VII fusions in vitro in permeabilized cells. Considered together, these data support the hypothesis that protein VII is a major NLS-containing adaptor for receptor-mediated import of adenovirus DNA and that multiple import pathways are utilized to promote efficient nuclear entry of the viral genome.

Mucosal IgG and IgA Responses to Human Papillomavirus Type 16 Capsid Proteins in HPV16-Infected Women without Visible Pathology

2003 ◽  
Vol 16 (2) ◽  
pp. 159-168 ◽  
Author(s):  
L. Rocha-Zavaleta ◽  
A.L. Pereira-Suarez ◽  
G. Yescas ◽  
R.M. Cruz-Mimiaga ◽  
A. Garcia-Carranca ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Capsid Proteins ◽  
Human Papillomavirus Type 16 ◽  
Mucosal Igg

scholarly journals Nuclear Import Receptors and hnRNP K Mediates Nuclear and Stress Granule Localization of SIRLOIN

2021 ◽  
Author(s):  
Jialin Yao ◽  
Qiao Zhou ◽  
Hengyi Xiao ◽  
Da Jia ◽  
Qingxiang Sun
Keyword(s):  
Nuclear Import ◽  
Rna Binding ◽  
Weak Interactions ◽  
Underlying Mechanism ◽  
Stress Granule ◽  
Hnrnp K ◽  
Permeabilized Cells ◽  
Import Receptors ◽  
Rna Motif ◽  
Import Receptor

Abstract The majority of lncRNAs and a small fraction of mRNAs localize in the cell nucleus to exert their functions. A SIRLOIN RNA motif was previously reported to drive its nuclear localization by the RNA-binding protein hnRNP K. However, the underlying mechanism remains unclear. Here, we report crystal structures of hnRNP K in complex with SIRLOIN, and with the nuclear import receptor (NIR) Impα1, respectively. The protein hnRNP K bound to SIRLOIN with multiple weak interactions, and interacted Impα1 using an independent high-affinity site. Forming a complex with hnRNP K and Impα1 was essential for the nuclear and stress granule localization of SIRLOIN in semi-permeabilized cells. Nuclear import of SIRLOIN enhanced with increasing NIR concentrations, but its stress granule localization peaked at a low NIR concentration. Collectively, we propose a mechanism of SIRLOIN localization, in which NIRs functioned as drivers/regulators, and hnRNP K as an adaptor.

scholarly journals SignalsThat Dictate Nuclear Localization of Human Papillomavirus Type 16Oncoprotein E6 in LivingCells

2003 ◽  
Vol 77 (24) ◽  
pp. 13232-13247 ◽  
Author(s):  
Mingfang Tao ◽  
Michael Kruhlak ◽  
Shuhua Xia ◽  
Elliot Androphy ◽  
Zhi-Ming Zheng
Keyword(s):  
Human Papillomavirus ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Protein ◽  
Fluorescent Protein ◽  
Present Report ◽  
Cell Cycle Control ◽  
Point Mutations ◽  
Coding Region ◽  
Nuclear Localization Signals

ABSTRACT Human papillomavirus (HPV) type 16 E6 (16E6) is an oncogenic, multifunctional nuclear protein that induces p53 degradation and perturbs normal cell cycle control, leading to immortalization and transformation of infected keratinocytes and epithelial cells. Although it is unclear how 16E6 disrupts the epigenetic profile of host genes, its presence in the nucleus is a key feature. The present report describes intrinsic properties of 16E6 that influence its nuclear import in living cells. When the coding region of full-length 16E6 was inserted in frame into the C terminus of green fluorescent protein (GFP), it effectively prevented the 16E6 pre-mRNA from being spliced and led to the expression of a GFP-E6 fusion which localized predominantly to the nucleus. Further studies identified three novel nuclear localization signals (NLSs) in 16E6 that drive the protein to accumulate in the nucleus. We found that all three NLS sequences are rich in positively charged basic residues and that point mutations in these key residues could abolish the retention of 16E6 in the nucleus as well as the p53 degradation and cell immortalization activities of the protein. When inserted into corresponding regions of low-risk HPV type 6 E6, the three NLS sequences described for 16E6 functioned actively in converting the normally cytoplasmic HPV type 6 E6 into a nuclear protein. The separate NLS sequences, however, appear to play different roles in nuclear import and retention of HPV E6. The discovery of three unique NLS sequences in 16E6 provides new insights into the nuclear association of 16E6 which may reveal other novel activities of this important oncogenic protein.

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