Ribosomal protein and biogenesis factors affect multiple steps during movement of the Saccharomyces cerevisiae Ty1 retrotransposon

Abstract

BackgroundA large number of Saccharomyces cerevisiae cellular factors modulate the movement of the retrovirus-like transposon Ty1. Surprisingly, a significant number of chromosomal genes required for Ty1 transposition encode components of the translational machinery, including ribosomal proteins, ribosomal biogenesis factors, protein trafficking proteins and protein or RNA modification enzymes.ResultsTo assess the mechanistic connection between Ty1 mobility and the translation machinery, we have determined the effect of these mutations on ribosome biogenesis and Ty1 transcriptional and post-transcriptional regulation. Lack of genes encoding ribosomal proteins or ribosome assembly factors causes reduced accumulation of the ribosomal subunit with which they are associated. In addition, these mutations cause decreased Ty1 + 1 programmed translational frameshifting, and reduced Gag protein accumulation despite at least normal levels of Ty1 mRNA. Several ribosome subunit mutations increase the level of both an internally initiated Ty1 transcript and its encoded truncated Gag-p22 protein, which inhibits transposition.ConclusionsTogether, our results suggest that this large class of cellular genes modulate Ty1 transposition through multiple pathways. The effects are largely post-transcriptional acting at a variety of levels that may include translation initiation, protein stability and subcellular protein localization.Electronic supplementary materialThe online version of this article (doi:10.1186/s13100-015-0053-5) contains supplementary material, which is available to authorized users.

Ribosome Biogenesis Modulates Ty1 Copy Number Control in Saccharomyces cerevisiae

“… Suresh et al (2015) reported that Ty1i RNA and p22/p18 levels increase in several ribosome biogenesis mutants including rps0b Δ. Therefore, endogenous levels of Ty1 mRNA, Ty1i RNA, Gag, and p22/p18 were determined in loc1 Δ, rps0b Δ, and rpl7a Δ CNC mutants ( Figure 4 ).…”

“…Therefore, endogenous levels of Ty1 mRNA, Ty1i RNA, Gag, and p22/p18 were determined in loc1 Δ, rps0b Δ, and rpl7a Δ CNC mutants ( Figure 4 ). To clearly distinguish Ty1i RNA from Ty1 mRNA ( Saha et al 2015 ; Suresh et al 2015 ), poly(A) + RNA was subjected to northern blot analysis using a 32 P-labeled riboprobe containing Ty1 nucleotides 1266–1601 that hybridizes with Ty1 mRNA and Ty1i transcripts; ACT1 mRNA served as a loading control ( Figure 4A ). Ty1 transcripts were below the limit of detection in wild type or CNC − mutants since there is only one Ty1 element present in the CNC − background.…”

“…We observed a slight decrease in counts assigned to both regions in the loc1 Δ mutant. However, as Ty1 mRNA is more abundant than the Ty1i transcripts ( Figure 4A ) ( Saha et al 2015 ; Suresh et al 2015 ), even a large fold change in Ty1i RNA might be undetectable by RNA-seq. In agreement with this idea, only a modest increase in Ty1i RNA relative to Ty1 mRNA was observed in the BY4742 loc1 Δ mutant as determined by northern analysis ( Figure 4A ).…”

The Mediator co-activator complex regulates Ty1 retromobility by controlling the balance between Ty1i and Ty1 promoters

“…A key insight into the mechanism by which tail module triad gene deletions cause decreased Ty1 mobility was obtained by northern analysis of Ty1 polyA + transcripts, which revealed increased levels of the internally generated, inhibitory Ty1i transcript in these deletion mutants (Fig 4). Increased Ty1i RNA was accompanied by elevated levels of p22-Gag, which interferes with VLP formation and production of Ty1 cDNA [25,30]. The increased expression of Ty1i is caused by a direct effect on transcription, as opposed to Ty1i RNA processing or stability, based on the altered occupancy of Pol II in a med3 Δ med15 Δ yeast mutant (Fig 4).…”

Erratum to: ribosomal protein and biogenesis factors affect multiple steps during movement of the Saccharomyces cerevisiae Ty1 retrotransposon

“…Unfortunately, the original version of this article [ 1 ] contained an error. The author’s name, ‘Arun Kananganat’ , was spelt incorrectly.…”