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Foamy Virus Protein — Nucleic Acid Interactions during Particle Morphogenesis

View Article: PubMed Central - PubMed

ABSTRACT

Compared with orthoretroviruses, our understanding of the molecular and cellular replication mechanism of foamy viruses (FVs), a subfamily of retroviruses, is less advanced. The FV replication cycle differs in several key aspects from orthoretroviruses, which leaves established retroviral models debatable for FVs. Here, we review the general aspect of the FV protein-nucleic acid interactions during virus morphogenesis. We provide a summary of the current knowledge of the FV genome structure and essential sequence motifs required for RNA encapsidation as well as Gag and Pol binding in combination with details about the Gag and Pol biosynthesis. This leads us to address open questions in FV RNA engagement, binding and packaging. Based on recent findings, we propose to shift the point of view from individual glycine-arginine-rich motifs having functions in RNA interactions towards envisioning the FV Gag C-terminus as a general RNA binding protein module. We encourage further investigating a potential new retroviral RNA packaging mechanism, which seems more complex in terms of the components that need to be gathered to form an infectious particle. Additional molecular insights into retroviral protein-nucleic acid interactions help us to develop safer, more specific and more efficient vectors in an era of booming genome engineering and gene therapy approaches.

No MeSH data available.


Pathways of FV RNA and protein trafficking resulting in capsid assembly and particle release. Please note that for simplicity budding of FV capsids at intracellular membranes was omitted. Known and putative trafficking pathways (marked by the dashed area with the question mark in the center) of viral RNAs from the nucleus into the cytoplasm to the capsid assembly site at the microtubule organizing center (MTOC) are shown. Putative RNA-protein interactions and assembly intermediates are depicted, as well as four different variants of vgRNA dimerization throughout the transport pathway to the assembly site illustrated. Known cellular cofactors involved in FV RNA trafficking or protein-RNA interaction are mentioned at the respective subcellular locations. Dashed arrows indicate the potential pathway leading to reintegration of vgDNA originating from preassembled capsids, which underwent reverse transcription prior to particle release [13]. CRM1: chromosomal maintenance 1; ANP32: acidic (leucine-rich) nuclear phosphoprotein 32 kDa; HuR: human antigen R; DDX6: DEAD-box helicase 6; PIC: pre-initiation complex.
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viruses-08-00243-f005: Pathways of FV RNA and protein trafficking resulting in capsid assembly and particle release. Please note that for simplicity budding of FV capsids at intracellular membranes was omitted. Known and putative trafficking pathways (marked by the dashed area with the question mark in the center) of viral RNAs from the nucleus into the cytoplasm to the capsid assembly site at the microtubule organizing center (MTOC) are shown. Putative RNA-protein interactions and assembly intermediates are depicted, as well as four different variants of vgRNA dimerization throughout the transport pathway to the assembly site illustrated. Known cellular cofactors involved in FV RNA trafficking or protein-RNA interaction are mentioned at the respective subcellular locations. Dashed arrows indicate the potential pathway leading to reintegration of vgDNA originating from preassembled capsids, which underwent reverse transcription prior to particle release [13]. CRM1: chromosomal maintenance 1; ANP32: acidic (leucine-rich) nuclear phosphoprotein 32 kDa; HuR: human antigen R; DDX6: DEAD-box helicase 6; PIC: pre-initiation complex.

Mentions: Furthermore, nuclear export of PFV Gag encoding vgRNA is mediated by the karyopherin chromosomal maintenance 1 (CRM1) and also depends on the adaptor proteins acidic (leucine-rich) nuclear phosphoprotein 32 kDa (ANP32) A and B as well as interaction of the RNA binding protein human antigen R (HuR) with yet unknown elements in the PFV vgRNA (Figure 5) [52].


Foamy Virus Protein — Nucleic Acid Interactions during Particle Morphogenesis
Pathways of FV RNA and protein trafficking resulting in capsid assembly and particle release. Please note that for simplicity budding of FV capsids at intracellular membranes was omitted. Known and putative trafficking pathways (marked by the dashed area with the question mark in the center) of viral RNAs from the nucleus into the cytoplasm to the capsid assembly site at the microtubule organizing center (MTOC) are shown. Putative RNA-protein interactions and assembly intermediates are depicted, as well as four different variants of vgRNA dimerization throughout the transport pathway to the assembly site illustrated. Known cellular cofactors involved in FV RNA trafficking or protein-RNA interaction are mentioned at the respective subcellular locations. Dashed arrows indicate the potential pathway leading to reintegration of vgDNA originating from preassembled capsids, which underwent reverse transcription prior to particle release [13]. CRM1: chromosomal maintenance 1; ANP32: acidic (leucine-rich) nuclear phosphoprotein 32 kDa; HuR: human antigen R; DDX6: DEAD-box helicase 6; PIC: pre-initiation complex.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035957&req=5

viruses-08-00243-f005: Pathways of FV RNA and protein trafficking resulting in capsid assembly and particle release. Please note that for simplicity budding of FV capsids at intracellular membranes was omitted. Known and putative trafficking pathways (marked by the dashed area with the question mark in the center) of viral RNAs from the nucleus into the cytoplasm to the capsid assembly site at the microtubule organizing center (MTOC) are shown. Putative RNA-protein interactions and assembly intermediates are depicted, as well as four different variants of vgRNA dimerization throughout the transport pathway to the assembly site illustrated. Known cellular cofactors involved in FV RNA trafficking or protein-RNA interaction are mentioned at the respective subcellular locations. Dashed arrows indicate the potential pathway leading to reintegration of vgDNA originating from preassembled capsids, which underwent reverse transcription prior to particle release [13]. CRM1: chromosomal maintenance 1; ANP32: acidic (leucine-rich) nuclear phosphoprotein 32 kDa; HuR: human antigen R; DDX6: DEAD-box helicase 6; PIC: pre-initiation complex.
Mentions: Furthermore, nuclear export of PFV Gag encoding vgRNA is mediated by the karyopherin chromosomal maintenance 1 (CRM1) and also depends on the adaptor proteins acidic (leucine-rich) nuclear phosphoprotein 32 kDa (ANP32) A and B as well as interaction of the RNA binding protein human antigen R (HuR) with yet unknown elements in the PFV vgRNA (Figure 5) [52].

View Article: PubMed Central - PubMed

ABSTRACT

Compared with orthoretroviruses, our understanding of the molecular and cellular replication mechanism of foamy viruses (FVs), a subfamily of retroviruses, is less advanced. The FV replication cycle differs in several key aspects from orthoretroviruses, which leaves established retroviral models debatable for FVs. Here, we review the general aspect of the FV protein-nucleic acid interactions during virus morphogenesis. We provide a summary of the current knowledge of the FV genome structure and essential sequence motifs required for RNA encapsidation as well as Gag and Pol binding in combination with details about the Gag and Pol biosynthesis. This leads us to address open questions in FV RNA engagement, binding and packaging. Based on recent findings, we propose to shift the point of view from individual glycine-arginine-rich motifs having functions in RNA interactions towards envisioning the FV Gag C-terminus as a general RNA binding protein module. We encourage further investigating a potential new retroviral RNA packaging mechanism, which seems more complex in terms of the components that need to be gathered to form an infectious particle. Additional molecular insights into retroviral protein-nucleic acid interactions help us to develop safer, more specific and more efficient vectors in an era of booming genome engineering and gene therapy approaches.

No MeSH data available.