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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.


Related in: MedlinePlus

Foamy virus replication strategy and particle structure. (a) Comparative illustration of orthoretroviral and foamyviral replication cycles. The two main capsid assembly strategies utilized by retroviruses are illustrated in the center. C-type assembly comprises simultaneous assembly and budding processes at the plasma membrane. In contrast B/D type assembly is a two-step process with cytoplasmic preassembly of the capsid preceding budding at cellular membranes. Processes of entry and assembly of FVs, differing to that of orthoretroviruses, are illustrated to the left and right, respectively. FV specific replication steps are connected by dashed arrows, and replication steps specific to orthoretroviruses or common to both types of retroviruses are connected by solid arrows. MTOC: microtubule organizing center; ER: endoplasmic reticulum. (b) Schematic representation of the prototype FV isolate (PFV) particle structure. pr: precursor protein; p: protein; gp: glycoprotein. Panels (a) and (b) are adapted from [18].
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viruses-08-00243-f001: Foamy virus replication strategy and particle structure. (a) Comparative illustration of orthoretroviral and foamyviral replication cycles. The two main capsid assembly strategies utilized by retroviruses are illustrated in the center. C-type assembly comprises simultaneous assembly and budding processes at the plasma membrane. In contrast B/D type assembly is a two-step process with cytoplasmic preassembly of the capsid preceding budding at cellular membranes. Processes of entry and assembly of FVs, differing to that of orthoretroviruses, are illustrated to the left and right, respectively. FV specific replication steps are connected by dashed arrows, and replication steps specific to orthoretroviruses or common to both types of retroviruses are connected by solid arrows. MTOC: microtubule organizing center; ER: endoplasmic reticulum. (b) Schematic representation of the prototype FV isolate (PFV) particle structure. pr: precursor protein; p: protein; gp: glycoprotein. Panels (a) and (b) are adapted from [18].

Mentions: Today spumaviruses, also called foamy viruses (FVs), comprise the only genus in the Spumaretrovirinae subfamily of retroviruses [1]. Becoming effective in 2005, a taxonomic reorganization of the Retroviridae family was issued as a consequence of accumulating evidence demonstrating that the replication strategy of FVs differs in several aspects from that of the other retroviral genera, which are nowadays grouped into the second, large subfamily of Orthoretrovirinae (Figure 1a) [1,2]. Interestingly, several of the “special replication features” of FVs bear some homology to characteristics of yet another virus family, the RNA genome encapsidating and reverse transcribing Hepadnaviridae [3].


Foamy Virus Protein — Nucleic Acid Interactions during Particle Morphogenesis
Foamy virus replication strategy and particle structure. (a) Comparative illustration of orthoretroviral and foamyviral replication cycles. The two main capsid assembly strategies utilized by retroviruses are illustrated in the center. C-type assembly comprises simultaneous assembly and budding processes at the plasma membrane. In contrast B/D type assembly is a two-step process with cytoplasmic preassembly of the capsid preceding budding at cellular membranes. Processes of entry and assembly of FVs, differing to that of orthoretroviruses, are illustrated to the left and right, respectively. FV specific replication steps are connected by dashed arrows, and replication steps specific to orthoretroviruses or common to both types of retroviruses are connected by solid arrows. MTOC: microtubule organizing center; ER: endoplasmic reticulum. (b) Schematic representation of the prototype FV isolate (PFV) particle structure. pr: precursor protein; p: protein; gp: glycoprotein. Panels (a) and (b) are adapted from [18].
© Copyright Policy
Related In: Results  -  Collection

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

viruses-08-00243-f001: Foamy virus replication strategy and particle structure. (a) Comparative illustration of orthoretroviral and foamyviral replication cycles. The two main capsid assembly strategies utilized by retroviruses are illustrated in the center. C-type assembly comprises simultaneous assembly and budding processes at the plasma membrane. In contrast B/D type assembly is a two-step process with cytoplasmic preassembly of the capsid preceding budding at cellular membranes. Processes of entry and assembly of FVs, differing to that of orthoretroviruses, are illustrated to the left and right, respectively. FV specific replication steps are connected by dashed arrows, and replication steps specific to orthoretroviruses or common to both types of retroviruses are connected by solid arrows. MTOC: microtubule organizing center; ER: endoplasmic reticulum. (b) Schematic representation of the prototype FV isolate (PFV) particle structure. pr: precursor protein; p: protein; gp: glycoprotein. Panels (a) and (b) are adapted from [18].
Mentions: Today spumaviruses, also called foamy viruses (FVs), comprise the only genus in the Spumaretrovirinae subfamily of retroviruses [1]. Becoming effective in 2005, a taxonomic reorganization of the Retroviridae family was issued as a consequence of accumulating evidence demonstrating that the replication strategy of FVs differs in several aspects from that of the other retroviral genera, which are nowadays grouped into the second, large subfamily of Orthoretrovirinae (Figure 1a) [1,2]. Interestingly, several of the “special replication features” of FVs bear some homology to characteristics of yet another virus family, the RNA genome encapsidating and reverse transcribing Hepadnaviridae [3].

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.


Related in: MedlinePlus