scholarly journals Subcellular Trafficking of the Papillomavirus Genome during Initial Infection: The Remarkable Abilities of Minor Capsid Protein L2

Viruses ◽  
2017 ◽  
Vol 9 (12) ◽  
pp. 370 ◽  
Author(s):  
Samuel Campos
Keyword(s):  
Capsid Protein ◽  
Subcellular Trafficking ◽  
Minor Capsid Protein ◽  
Initial Infection

scholarly journals Subcellular Trafficking of the Papillomavirus Genome during Initial Infection: The Remarkable Abilities of Minor Capsid Protein L2

2017 ◽  
Author(s):  
Samuel K. Campos
Keyword(s):  
Human Papillomavirus ◽  
Paradigm Shift ◽  
Viral Genome ◽  
Retrograde Transport ◽  
Nuclear Accumulation ◽  
Subcellular Trafficking ◽  
Minor Capsid Protein ◽  
Initial Infection ◽  
Host Cell Proteins

Beginning in 2012, our understanding of human papillomavirus (HPV) subcellular trafficking has undergone a drastic paradigm shift. Work from multiple laboratories has revealed that HPV has evolved a unique means to deliver its viral genome (vDNA) to the cell nucleus, relying on a myriad of host cell proteins and processes. The major breakthrough finding from these recent endeavors was the realization of L2-dependent utilization of cellular sorting factors for the retrograde transport of vDNA away from degradative endo/lysosomal compartments to the Golgi, prior to mitosis-dependent nuclear accumulation of L2/vDNA. An overview of current models of HPV entry, subcellular trafficking, and the role of L2 during initial infection is provided below, highlighting unresolved questions and gaps in knowledge.

scholarly journals Furin Cleavage of L2 during Papillomavirus Infection: Minimal Dependence on Cyclophilins

2016 ◽  
Vol 90 (14) ◽  
pp. 6224-6234 ◽  
Author(s):  
Matthew P. Bronnimann ◽  
Christine M. Calton ◽  
Samantha F. Chiquette ◽  
Shuaizhi Li ◽  
Mingfeng Lu ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Current Model ◽  
Hpv Infection ◽  
Cleavage Product ◽  
Protein Domain ◽  
Furin Cleavage ◽  
Minor Capsid Protein ◽  
Papillomavirus Infection ◽  
Successful Infection ◽  
N Terminus

ABSTRACTDespite an abundance of evidence supporting an important role for the cleavage of minor capsid protein L2 by cellular furin, direct cleavage of capsid-associated L2 during human papillomavirus 16 (HPV16) infection remains poorly characterized. The conserved cleavage site, close to the L2 N terminus, confounds observation and quantification of the small cleavage product by SDS-PAGE. To overcome this difficulty, we increased the size shift by fusing a compact protein domain, thePropionibacterium shermaniitranscarboxylase domain (PSTCD), to the N terminus of L2. The infectious PSTCD-L2 virus displayed an appreciable L2 size shift during infection of HaCaT keratinocytes. Cleavage under standard cell culture conditions rarely exceeded 35% of total L2. Cleavage levels were enhanced by the addition of exogenous furin, and the absolute levels of infection correlated to the level of L2 cleavage. Cleavage occurred on both the HaCaT cell surface and extracellular matrix (ECM). Contrary to current models, experiments on the involvement of cyclophilins revealed little, if any, role for these cellular enzymes in the modulation of furin cleavage. HPV16 L2 contains two consensus cleavage sites, Arg5 (2RHKR5) and Arg12 (9RTKR12). Mutant PSTCD-L2 viruses demonstrated that although furin can cleave either site, cleavage must occur at Arg12, as cleavage at Arg5 alone is insufficient for successful infection. Mutation of the conserved cysteine residues revealed that the Cys22-Cys28 disulfide bridge is not required for cleavage. The PSTCD-L2 virus or similar N-terminal fusions will be valuable tools to study additional cellular and viral determinants of furin cleavage.IMPORTANCEFurin cleavage of minor capsid protein L2 during papillomavirus infection has been difficult to directly visualize and quantify, confounding efforts to study this important step of HPV infection. Fusion of a small protein domain to the N terminus greatly facilitates direct visualization of the cleavage product, revealing important characteristics of this critical process. Contrary to the current model, we found that cleavage is largely independent of cyclophilins, suggesting that cyclophilins act either in parallel to or downstream of furin to trigger exposure of a conserved N-terminal L2 epitope (RG-1) during infection. Based on this finding, we strongly caution against using L2 RG-1 epitope exposure as a convenient but indirect proxy of furin cleavage.

scholarly journals Neutralization of HPV16, 18, 31, and 58 pseudovirions with antisera induced by immunizing rabbits with synthetic peptides representing segments of the HPV16 minor capsid protein L2 surface region

Virology ◽  
2007 ◽  
Vol 358 (2) ◽  
pp. 266-272 ◽  
Author(s):  
Kazunari Kondo ◽  
Yoshiyuki Ishii ◽  
Hiroyuki Ochi ◽  
Tamae Matsumoto ◽  
Hiroyuki Yoshikawa ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Synthetic Peptides ◽  
Surface Region ◽  
Minor Capsid Protein

scholarly journals Derivation of a triple mosaic adenovirus based on modification of the minor capsid protein IX

Virology ◽  
2008 ◽  
Vol 377 (2) ◽  
pp. 391-400 ◽  
Author(s):  
Yizhe Tang ◽  
Long P. Le ◽  
Qiana L. Matthews ◽  
Tie Han ◽  
Hongju Wu ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Minor Capsid Protein ◽  
Protein Ix

Expression of avian reovirus minor capsid protein in plants

2011 ◽  
Vol 173 (2) ◽  
pp. 287-293 ◽  
Author(s):  
Shih-Wei Lu ◽  
Kuo-Chih Wang ◽  
Hung-Jen Liu ◽  
Ching-Dong Chang ◽  
Hao-Jen Huang ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Avian Reovirus ◽  
Minor Capsid Protein

scholarly journals The Positively Charged Termini of L2 Minor Capsid Protein Required for Bovine Papillomavirus Infection Function Separately in Nuclear Import and DNA Binding

2004 ◽  
Vol 78 (24) ◽  
pp. 13447-13454 ◽  
Author(s):  
Alyson Fay ◽  
William H. Yutzy ◽  
Richard B. S. Roden ◽  
Junona Moroianu
Keyword(s):  
Dna Binding ◽  
Capsid Protein ◽  
Nuclear Import ◽  
Bovine Papillomavirus ◽  
Sequence Specificity ◽  
Viral Dna ◽  
Minor Capsid Protein ◽  
Nuclear Localization Signals ◽  
Promiscuous Dna ◽  
Positively Charged

ABSTRACT During the papillomavirus (PV) life cycle, the L2 minor capsid protein enters the nucleus twice: in the initial phase after entry of virions into cells and in the productive phase to mediate encapsidation of the newly replicated viral genome. Therefore, we investigated the interactions of the L2 protein of bovine PV type 1 (BPV1) with the nuclear import machinery and the viral DNA. We found that BPV1 L2 bound to the karyopherin α2 (Kap α2) adapter and formed a complex with Kap α2β1 heterodimers. Previous data have shown that the positively charged termini of BPV1 L2 are required for BPV1 infection after the binding of the virions to the cell surface. We determined that these BPV1 L2 termini function as nuclear localization signals (NLSs). Both the N-terminal NLS (nNLS) and the C-terminal NLS (cNLS) interacted with Kap α2, formed a complex with Kap α2β1 heterodimers, and mediated nuclear import via a Kap α2β1 pathway. Interestingly, the cNLS was also the major DNA binding site of BPV1 L2. Consistent with the promiscuous DNA encapsidation by BPV1 pseudovirions, this DNA binding occurred without nucleotide sequence specificity. Moreover, an L2 mutant encoding a scrambled version of the cNLS, which supports production of virions, rescued the DNA binding but not the Kap α2 interaction. These data support a model in which BPV1 L2 functions as an adapter between the viral DNA via the cNLS and the Kaps via the nNLS and facilitates nuclear import of the DNA during infection.

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