Ty3 GAG3 and POL3 genes encode the components of intracellular particles

@article{Hansen1992Ty3GA,
  title={Ty3 GAG3 and POL3 genes encode the components of intracellular particles},
  author={L. J. Hansen and Douglas L. Chalker and K J Orlinsky and Suzanne B. Sandmeyer},
  journal={Journal of Virology},
  year={1992},
  volume={66},
  pages={1414 - 1424}
}
Ty3 is a Saccharomyces cerevisiae retrotransposon that integrates near the transcription initiation sites of polymerase III-transcribed genes. It is distinct from the copialike Ty1 and Ty2 retrotransposons of S. cerevisiae in both the sequences of encoded proteins and gene order. It is a member of the gypsylike family of retrotransposons which resemble animal retroviruses. This study was undertaken to investigate the nucleocapsid particle of a transpositionally active gypsylike retrotransposon… 
Ty3, a Position-specific Retrotransposon in Budding Yeast.
TLDR
Identification of nuclear pore, DNA replication, transcription, and repair host factors that affect retrotransposition has provided insights into how hosts and retrotransposons interact to balance genome stability and plasticity.
Expression and Processing of Proteins Encoded by the Saccharomyces Retrotransposon Ty5
TLDR
The ratio of Ty5 Gag to Pol averaged 5:1 throughout the time course experiment, suggesting that differential protein stability regulates the amounts of these proteins.
Ty3 Nucleocapsid Controls Localization of Particle Assembly
TLDR
These findings are consistent with the model that Ty3 assembly is associated with P-body components and hypothesize that the NC domain acts as a molecular switch to control Gag3 conformational states that affect both assembly and localization.
Function of a retrotransposon nucleocapsid protein
TLDR
It is speculated that Ty3 NC, together with P-body and stress-granule proteins, plays a role in transitioning Ty3 RNA from translation template to gRNA, and that interactions between the acidic spacer domain of Ty3 Gag3 and the adjacent basic NC domain control condensation of the virus-like particle.
Ty3, a Position-Specific, Gypsy-Like Element in Saccharomyces cerevisiae
TLDR
These results argue that Ty3 insertion is highly specific for pol III-transcribed genes and development of varied and quantitative assays for transposition is facilitating use of the genomic resources in a high-throughput format.
Proteolytic processing of Ty3 proteins is required for transposition
TLDR
The region encoding a protease that is homologous to retroviral aspartyl proteases was identified and shown to be required for production of mature Ty3 proteins and transposition and the existence of an additional protein(s) of unknown function, encoded downstream of the protease-coding region, was deduced.
Ty3 Capsid Mutations Reveal Early and Late Functions of the Amino-Terminal Domain
TLDR
The data suggest that Ty3 proteins are concentrated first, assembly associated with P bodies occurs, and particle morphogenesis concludes with a post-reverse transcription, CA-dependent step, possibly indicating that multiple domains are involved.
Virus-like particles of the Ty3 retrotransposon assemble in association with P-body components.
TLDR
The hypothesis that P-bodies may serve to segregate translation and assembly functions of the Ty3 genomic RNA to promote assembly of virus-like particles is suggested.
Integrase Mediates Nuclear Localization of Ty3
TLDR
Viruslike particles from cells expressing a Ty3 element defective for nuclear localization were inactive in an in vitro integration assay, suggesting that nuclear entry is required to form active VLPs or that this motif is required for post-nuclear entry steps.
Thermal blockage of viruslike particle formation for the yeast retrotransposon Ty3 reveals differences in the cellular stress response
TLDR
Although overexpression of the yeast UBP3 gene allows VLPs to form and transposition to occur in the constitutively stressed ssa1 ssa2 strain, it does not alleviate the inhibition of these processes during stress induced by heat or ethanol, suggesting that the genetic and physical modes of stress response induction are not equivalent.
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References

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Ty3, a yeast retrotransposon associated with tRNA genes, has homology to animal retroviruses.
TLDR
The inferred order of functional domains within TYB3--protease, reverse transcriptase, and endonuclease--resembles the order in Drosophila element 17.6 and in animal retroviruses but is different from that found in yeast elements Ty1 and Ty2.
Characterization of a transpositionally active Ty3 element and identification of the Ty3 integrase protein
TLDR
The complete DNA sequence of a transpositionally competent Ty3 element, Ty3-1, is presented here and suggests that the 61- or 58-kDa protein, or both, provides the integrase function of Ty3.
Reverse transcriptase activity and Ty RNA are associated with virus-like particles in yeast
TLDR
The reverse transcriptase activity that, until now, has been presumed to mediate Ty transposition and show that it is sequestered in virus-like particles that also contain Ty RNA is identified.
The DNA intermediate in yeast Ty1 element transposition copurifies with virus-like particles: Cell-free Ty1 transposition
TLDR
A cell-free system for transposition of Ty1 DNA molecules into a bacteriophage lambda target is developed and mutations in the integrase coding region abolish transposition both in vivo and in vitro.
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TLDR
The results support the idea that Ty elements and retroviruses share a common origin and the numerous virus-like particles visible in thin sections of Ty transposition-induced cells appear to be infectious.
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TLDR
The sequences of the two classes of yeast transposon are compared with one another and with analogous elements, such as retroviral proviruses, cauliflower mosaic virus and copia sequences.
Ty3 integrates within the region of RNA polymerase III transcription initiation.
TLDR
Over 190 independent insertions into target plasmids of the retrovirus-like element Ty3 were recovered and mapped, and this is the first report directly linking a discrete genomic function with preferential insertion of a retrotransposon.
A yeast sigma composite element, TY3, has properties of a retrotransposon.
TLDR
Examination of genomic DNA from five laboratory strains indicates that the 4.7 kilobase pair internal domain is present in one to four copies per haploid genome and that the genomic location of this domain differs from strain to strain.
Virus‐like particle formation of Drosophila copia through autocatalytic processing.
TLDR
It is concluded that copia VLPs are produced through autocatalytic processing of the precursor polyprotein encoded by the splicedCopia RNA, which is one of the major transcripts of copia.
The nucleotide sequences of copia and copia-related RNA in Drosophila virus-like particles
TLDR
To further clarify the relationship between copia and copia-related RNA in VLPs (VLP H-RNA), nucleotide sequences were determined and compared and it is shown that, in contrast to 17.6 ORF2, ORFs of copia have no extensive amino-acid sequence homology to the RT region2 of the reverse transcriptase of retrovirus in vertebrates.
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