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Ty3 Retrotransposon Hijacks Mating Yeast RNA Processing Bodies to Infect New Genomes.

Bilanchone V, Clemens K, Kaake R, Dawson AR, Matheos D, Nagashima K, Sitlani P, Patterson K, Chang I, Huang L, Sandmeyer S - PLoS Genet. (2015)

Bottom Line: Components of RNA processing bodies including DEAD box helicases Dhh1/DDX6 and Ded1/DDX3, Sm-like protein Lsm1, decapping protein Dcp2, and 5' to 3' exonuclease Xrn1 were among the proteins identified.These proteins associated with Ty3 proteins and RNA, and were required for formation of Ty3 VLP retrosome assembly factories and for retrotransposition.Specifically, Dhh1/DDX6 was required for normal levels of Ty3 genomic RNA, and Lsm1 and Xrn1 were required for association of Ty3 protein and RNA into retrosomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, University of California, Irvine, Irvine, California, United States of America.

ABSTRACT
Retrotransposition of the budding yeast long terminal repeat retrotransposon Ty3 is activated during mating. In this study, proteins that associate with Ty3 Gag3 capsid protein during virus-like particle (VLP) assembly were identified by mass spectrometry and screened for roles in mating-stimulated retrotransposition. Components of RNA processing bodies including DEAD box helicases Dhh1/DDX6 and Ded1/DDX3, Sm-like protein Lsm1, decapping protein Dcp2, and 5' to 3' exonuclease Xrn1 were among the proteins identified. These proteins associated with Ty3 proteins and RNA, and were required for formation of Ty3 VLP retrosome assembly factories and for retrotransposition. Specifically, Dhh1/DDX6 was required for normal levels of Ty3 genomic RNA, and Lsm1 and Xrn1 were required for association of Ty3 protein and RNA into retrosomes. This role for components of RNA processing bodies in promoting VLP assembly and retrotransposition during mating in a yeast that lacks RNA interference, contrasts with roles proposed for orthologous components in animal germ cell ribonucleoprotein granules in turnover and epigenetic suppression of retrotransposon RNAs.

No MeSH data available.


Related in: MedlinePlus

Ty3 expression enhances, but is not required for PB formation.Dhh1-GFP foci were evaluated in Ty3 WT and  cells treated with α-factor for 4 h or left untreated. Cells in (A, B, C) were imaged by widefield microscopy as described (Materials and Methods, S1 Text, Supporting Materials and Methods). Scale bar = 5 μm. (A) Pheromone treatment causes PB formation in Ty3(WT) cells. Insert indicates % cells with GFP foci (mean ± SD). (B) Ty3 foci are present in similar percentages of WT and far1Δ cells. Insert indicates % cells with Ty3-mCherry foci (mean ± SD). Cells contained Ty3-mCh-expressing plasmid under the native promoter (pTD3655). (C) Ty3 expression is reduced in far1Δ cells. Western blot analysis of Gag3 proteins products in WT and far1Δ cells, either uninduced or induced with α-factor. Ratio of CA/Pgk1 loading control is average of three independent cultures. (D) Pheromone induced Ty3 expression enhances PB formation in far1Δ cells. Insert as described in (A). (E) Ty3 transposition is reduced in far1Δ cells. Pheromone-induced transposition was as described (Materials and Methods).
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pgen.1005528.g004: Ty3 expression enhances, but is not required for PB formation.Dhh1-GFP foci were evaluated in Ty3 WT and cells treated with α-factor for 4 h or left untreated. Cells in (A, B, C) were imaged by widefield microscopy as described (Materials and Methods, S1 Text, Supporting Materials and Methods). Scale bar = 5 μm. (A) Pheromone treatment causes PB formation in Ty3(WT) cells. Insert indicates % cells with GFP foci (mean ± SD). (B) Ty3 foci are present in similar percentages of WT and far1Δ cells. Insert indicates % cells with Ty3-mCherry foci (mean ± SD). Cells contained Ty3-mCh-expressing plasmid under the native promoter (pTD3655). (C) Ty3 expression is reduced in far1Δ cells. Western blot analysis of Gag3 proteins products in WT and far1Δ cells, either uninduced or induced with α-factor. Ratio of CA/Pgk1 loading control is average of three independent cultures. (D) Pheromone induced Ty3 expression enhances PB formation in far1Δ cells. Insert as described in (A). (E) Ty3 transposition is reduced in far1Δ cells. Pheromone-induced transposition was as described (Materials and Methods).

Mentions: Evidence that mating cell PB contain Ty3 proteins and are resistant to effects of deletions of scaffolding proteins, together with previous results showing that Ty3 expression at high levels actually drives formation of PB [6], suggested that expression of endogenous retrotransposons contributes to formation of mating cell PB foci. Although many retrotransposons including Ty1 are present in high-copy number, full-length Ty3 is represented by only two full-length copies in the Ty3(WT) strain, BY4741 [67], enabling a direct test of its role in mating-cell PB formation. The two endogenous full-length Ty3 elements were deleted from BY4741, creating the Ty3Δ strain (yVB1672). PB formation in these strains was monitored by C-terminal fusion of the chromosomal locus of the PB component DHH1 with GFP. The Ty3(WT) strain was treated with pheromone for 4 h or left untreated, and examined by fluorescence microscopy. As expected, induced cells showed 66% Dhh1-GFP foci compared to 8% in uninduced cells (Fig 4A).


Ty3 Retrotransposon Hijacks Mating Yeast RNA Processing Bodies to Infect New Genomes.

Bilanchone V, Clemens K, Kaake R, Dawson AR, Matheos D, Nagashima K, Sitlani P, Patterson K, Chang I, Huang L, Sandmeyer S - PLoS Genet. (2015)

Ty3 expression enhances, but is not required for PB formation.Dhh1-GFP foci were evaluated in Ty3 WT and  cells treated with α-factor for 4 h or left untreated. Cells in (A, B, C) were imaged by widefield microscopy as described (Materials and Methods, S1 Text, Supporting Materials and Methods). Scale bar = 5 μm. (A) Pheromone treatment causes PB formation in Ty3(WT) cells. Insert indicates % cells with GFP foci (mean ± SD). (B) Ty3 foci are present in similar percentages of WT and far1Δ cells. Insert indicates % cells with Ty3-mCherry foci (mean ± SD). Cells contained Ty3-mCh-expressing plasmid under the native promoter (pTD3655). (C) Ty3 expression is reduced in far1Δ cells. Western blot analysis of Gag3 proteins products in WT and far1Δ cells, either uninduced or induced with α-factor. Ratio of CA/Pgk1 loading control is average of three independent cultures. (D) Pheromone induced Ty3 expression enhances PB formation in far1Δ cells. Insert as described in (A). (E) Ty3 transposition is reduced in far1Δ cells. Pheromone-induced transposition was as described (Materials and Methods).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4589538&req=5

pgen.1005528.g004: Ty3 expression enhances, but is not required for PB formation.Dhh1-GFP foci were evaluated in Ty3 WT and cells treated with α-factor for 4 h or left untreated. Cells in (A, B, C) were imaged by widefield microscopy as described (Materials and Methods, S1 Text, Supporting Materials and Methods). Scale bar = 5 μm. (A) Pheromone treatment causes PB formation in Ty3(WT) cells. Insert indicates % cells with GFP foci (mean ± SD). (B) Ty3 foci are present in similar percentages of WT and far1Δ cells. Insert indicates % cells with Ty3-mCherry foci (mean ± SD). Cells contained Ty3-mCh-expressing plasmid under the native promoter (pTD3655). (C) Ty3 expression is reduced in far1Δ cells. Western blot analysis of Gag3 proteins products in WT and far1Δ cells, either uninduced or induced with α-factor. Ratio of CA/Pgk1 loading control is average of three independent cultures. (D) Pheromone induced Ty3 expression enhances PB formation in far1Δ cells. Insert as described in (A). (E) Ty3 transposition is reduced in far1Δ cells. Pheromone-induced transposition was as described (Materials and Methods).
Mentions: Evidence that mating cell PB contain Ty3 proteins and are resistant to effects of deletions of scaffolding proteins, together with previous results showing that Ty3 expression at high levels actually drives formation of PB [6], suggested that expression of endogenous retrotransposons contributes to formation of mating cell PB foci. Although many retrotransposons including Ty1 are present in high-copy number, full-length Ty3 is represented by only two full-length copies in the Ty3(WT) strain, BY4741 [67], enabling a direct test of its role in mating-cell PB formation. The two endogenous full-length Ty3 elements were deleted from BY4741, creating the Ty3Δ strain (yVB1672). PB formation in these strains was monitored by C-terminal fusion of the chromosomal locus of the PB component DHH1 with GFP. The Ty3(WT) strain was treated with pheromone for 4 h or left untreated, and examined by fluorescence microscopy. As expected, induced cells showed 66% Dhh1-GFP foci compared to 8% in uninduced cells (Fig 4A).

Bottom Line: Components of RNA processing bodies including DEAD box helicases Dhh1/DDX6 and Ded1/DDX3, Sm-like protein Lsm1, decapping protein Dcp2, and 5' to 3' exonuclease Xrn1 were among the proteins identified.These proteins associated with Ty3 proteins and RNA, and were required for formation of Ty3 VLP retrosome assembly factories and for retrotransposition.Specifically, Dhh1/DDX6 was required for normal levels of Ty3 genomic RNA, and Lsm1 and Xrn1 were required for association of Ty3 protein and RNA into retrosomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, University of California, Irvine, Irvine, California, United States of America.

ABSTRACT
Retrotransposition of the budding yeast long terminal repeat retrotransposon Ty3 is activated during mating. In this study, proteins that associate with Ty3 Gag3 capsid protein during virus-like particle (VLP) assembly were identified by mass spectrometry and screened for roles in mating-stimulated retrotransposition. Components of RNA processing bodies including DEAD box helicases Dhh1/DDX6 and Ded1/DDX3, Sm-like protein Lsm1, decapping protein Dcp2, and 5' to 3' exonuclease Xrn1 were among the proteins identified. These proteins associated with Ty3 proteins and RNA, and were required for formation of Ty3 VLP retrosome assembly factories and for retrotransposition. Specifically, Dhh1/DDX6 was required for normal levels of Ty3 genomic RNA, and Lsm1 and Xrn1 were required for association of Ty3 protein and RNA into retrosomes. This role for components of RNA processing bodies in promoting VLP assembly and retrotransposition during mating in a yeast that lacks RNA interference, contrasts with roles proposed for orthologous components in animal germ cell ribonucleoprotein granules in turnover and epigenetic suppression of retrotransposon RNAs.

No MeSH data available.


Related in: MedlinePlus