RNA polymerase III interferes with Ty3 integration

Connolly, Charles M.; Sandmeyer, Suzanne

doi:10.1016/s0014-5793(97)00200-7

Cited by 29 publications

(20 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3, B and C). Our data and those of Bridier-Nahmias et al (24) suggest that Ty1-IN interacts with Pol III subunits, whereas purified Pol III inhibits Ty3 element integration in vitro (24,71). Another major difference between Ty1 and Ty3 element insertion is that Ty1 elements preferentially insert into nucleosomes, in particular near the H2A/H2B interface, in a periodic manner (11)(12)(13)(14)73).…”

Section: Rpc34supporting

confidence: 56%

Ty1 Integrase Interacts with RNA Polymerase III-specific Subcomplexes to Promote Insertion of Ty1 Elements Upstream of Polymerase (Pol) III-transcribed Genes

Cheung

Chan

et al. 2016

Journal of Biological Chemistry

View full text Add to dashboard Cite

Section: Rpc34supporting

confidence: 56%

Ty1 Integrase Interacts with RNA Polymerase III-specific Subcomplexes to Promote Insertion of Ty1 Elements Upstream of Polymerase (Pol) III-transcribed Genes

Cheung

Chan

et al. 2016

Journal of Biological Chemistry

View full text Add to dashboard Cite

“…The C-terminal half of Brf also contacts C34 (19). Although there is no striking similarity between the sequences of Ty3 reverse transcriptase or integrase and C17 or C34 (analysis not shown), pol III inhibits Ty3 integration in vitro (33). A direct competition between the Ty3 preintegration complex and pol III for overlapping sites in the N-terminal region of Brf could help to explain this inhibitory effect of pol III.…”

Section: Discussionmentioning

confidence: 98%

The Brf and TATA-binding Protein Subunits of the RNA Polymerase III Transcription Factor IIIB Mediate Position-specific Integration of the Gypsy-like Element, Ty3

Yieh

Kassavetis

Geiduschek

et al. 2000

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Ty3 integrates into the transcription initiation sites of genes transcribed by RNA polymerase III. It is known that transcription factors (TF) IIIB and IIIC are important for recruiting Ty3 to its sites of integration upstream of tRNA genes, but that RNA polymerase III is not required. In order to investigate the respective roles of TFIIIB and TFIIIC, we have developed an in vitro integration assay in which Ty3 is targeted to the U6 small nuclear RNA gene, SNR6. Because TFIIIB can bind to the TATA box upstream of the U6 gene through contacts mediated by TATA-binding protein (TBP), TFIIIC is dispensable for in vitro transcription. Thus, this system offers an opportunity to test the role of TFIIIB independent of a requirement of TFIIIC. We demonstrate that the recombinant Brf and TBP subunits of TFIIIB, which interact over the SNR6 TATA box, direct integration at the SNR6 transcription initiation site in the absence of detectable TFIIIC or TFIIIB subunit B؆. These findings suggest that the minimal requirements for pol III transcription and Ty3 integration are very similar.Integration site selection is a key step in the retroelement life cycle, potentially influencing both the effect of the insertion on the host genome and the expression of the element itself. Similar to retroviruses, yeast Ty elements transpose through reverse transcription of an almost full-length RNA copy into a full-length DNA copy, which is integrated into the host genome. Despite very similar molecular mechanisms of integration, budding yeast elements (Tys), both gypsy-like (Ty3) and copialike (Ty1, 2, 4, and 5), differ from retroviruses in that they exhibit dramatic global integration site preferences (1-4). Ty1 elements, for example, integrate preferentially within a window of 750 bp, 1 upstream of genes transcribed by RNA polymerase III (pol III). Analysis of the yeast genome sequence shows that Ty2 and Ty4 also occupy this region upstream of a fraction of tRNA genes. Ty5 integrates into regions of silenced DNA, including the silent mating type loci and telomeres. Hence Ty1, Ty2, Ty4, and Ty5 exhibit regional integration specificity. Despite similarities with these other elements, Ty3 differs in that it integrates within a highly defined window, one or two base pairs (bp) upstream of pol III transcription initiation sites.Targeting of integration appears to be directed by the cooperative actions of Ty3 element-and cell-encoded factors. For example, in addition to the element-encoded integrase protein, Ty3 and Ty1 targeting requires the presence of a transcriptionally competent pol III promoter (5, 6), and Ty5 targeting requires factors involved in the establishment of silent chromatin (7).Class III genes, including plasmid-borne U6, 5S, and tRNA genes, are used in vivo for position-specific Ty3 integration. Comparison of integration sites suggests that Ty3 integration preference is not a direct function of specific local sequences. Each class of pol III-transcribed genes differs from the others in composition of promoter elements (8) and d...

show abstract

“…Ty5 elements are preferentially targeted for integration by the protein complex assembled at silenced regions (78). Ty3 integration requires binding of the transcription factors TFIIIB and TFIIIC but is inhibited by RNAP III, suggesting that the Ty3 integration machinery competes with RNAP III for interaction with TFIIIB and TFIIIC (13,35). Likewise, Ty1 has also been shown to have a strong preference for integration into regions upstream of genes transcribed by RNAP III (16).…”

Section: Discussionmentioning

confidence: 99%

Yeast Ty1 Retrotransposition Is Stimulated by a Synergistic Interaction between Mutations in Chromatin Assembly Factor I and Histone Regulatory Proteins

Qian

Huang

Hong

et al. 1998

Molecular and Cellular Biology

View full text Add to dashboard Cite

A screen for host mutations which increase the rate of transposition of Ty1 and Ty2 into a chromosomal target was used to identify factors influencing retroelement transposition. The fortuitous presence of a mutation in the CAC3 gene in the strain in which this screen was undertaken enabled us to discover that double mutaions of cac3 and hir3, but neither of the two single mutations, caused a dramatic increase in the rate of retrotransposition. We further showed that this effect was not due to an increase in the overall level of Ty1 mRNA. Two subtle cac3 phenotypes, slight methyl methanesulfonate (MMS) sensitivity and reduction of telomeric silencing, were significantly enhanced in the cac3 hir3 double mutant. In addition, the growth rate of the double mutant was reduced. HIR3 belongs to a class of HIR genes that regulate the transcription of histones, while Cac3p, together with Cac1p and Cac2p, forms chromatin assembly factor I. Other combinations of mutations in cac and hir genes (cac3 hir1, cac3 hir2, and cac2 hir3) also increase Ty transposition and MMS sensitivity and reduce the growth rate. A model explaining the synergistic interaction between cac and hir mutations in terms of alterations in chromatin structure is proposed.Retroviruses are currently under intensive study because they can elicit malignant tumors and cause AIDS. Furthermore, at least 0.1 to 0.6% of the human genome is composed of endogenous retroviruses and long-terminal-repeat (LTR)-containing retrotransposons, which resemble retroviruses in their structural organization and mode of transposition (38). The life cycle of these elements begins with the transcription of an integrated DNA copy of the element and the incorporation of the transcribed RNA into a viruslike particle composed of element-encoded proteins, including the capsid protein, protease, reverse transcriptase, and integrase. The RNA is then reverse transcribed into cDNA, which integrates into a new chromosomal location in the host cell (for a review, see reference 5). Such integration is required for retroviruses to induce disease, for example, by activating a nearby cellular protooncogene (70). Likewise, insertions of the yeast Ty1 element (5) can alter the regulation of nearby cellular genes.Common laboratory yeast (Saccharomyces cerevisiae) strains contain five types of Ty elements composed of central regions of DNA flanked by LTRs. Structural proteins and enzymatic activity are encoded within the central region (for reviews, see references 5 and 22). Ty1, Ty2, Ty4, and Ty5 elements are members of the copia class of retrotransposons, while Ty3 elements belong to the gypsy class. Ty1 and Ty2 elements are respectively present at about 30 to 35 and 5 to 15 copies per genome, contain the same LTR sequences (called delta elements), and have very similar internal regions. The more distantly related retrotransposons Ty3, Ty4, and Ty5 have different sets of LTRs, are present in lower copy numbers, and have not been observed to be insertional mutagens.Yeast retrotransposons provide ...

show abstract

RNA polymerase III interferes with Ty3 integration

Cited by 29 publications

References 42 publications

Ty1 Integrase Interacts with RNA Polymerase III-specific Subcomplexes to Promote Insertion of Ty1 Elements Upstream of Polymerase (Pol) III-transcribed Genes

Ty1 Integrase Interacts with RNA Polymerase III-specific Subcomplexes to Promote Insertion of Ty1 Elements Upstream of Polymerase (Pol) III-transcribed Genes

The Brf and TATA-binding Protein Subunits of the RNA Polymerase III Transcription Factor IIIB Mediate Position-specific Integration of the Gypsy-like Element, Ty3

Yeast Ty1 Retrotransposition Is Stimulated by a Synergistic Interaction between Mutations in Chromatin Assembly Factor I and Histone Regulatory Proteins

Contact Info

Product

Resources

About