Transfer RNA Genes: Landmarks for Integration of Mobile Genetic Elements in
            <i>Dictyostelium discoideum</i>

Marschalek, Rolf; Brechner, Thomas; Amon-Böhm, Elfi; Dingermann, Theo

doi:10.1126/science.2567533

Cited by 61 publications

(41 citation statements)

References 16 publications

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“…Ty3 insertion occurs with a strong preference near the tRNA gene transcription initiation site (13,14), and it seems possible that this insertion preference developed because of a regulatory advantage conferred by the neighboring placement on the chromosome. A very similar close association with tRNA genes has been found for the DRE retrotransposons from Dictyostelium discoideum (69,70).…”

supporting

confidence: 76%

tRNA genes as transcriptional repressor elements.

Hull¹,

Erickson²,

Johnston³

et al. 1994

Mol. Cell. Biol.

120

129

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Eukaryotic genomes frequently contain large numbers of repetitive RNA polymerase III (pol III) promoter elements interspersed between and within RNA pol II transcription units, and in several instances a regulatory relationship between the two types of promoter has been postulated. In the budding yeast Saccharomyces cerevisiae, tRNA genes are the only known interspersed pol III promoter-containing repetitive elements, and we find that they strongly inhibit transcription from adjacent pol II promoters in vivo. This inhibition requires active transcription of the upstream tRNA gene but is independent of its orientation and appears not to involve simple steric blockage of the pol II upstream activator sites. Evidence is presented that different pol II promoters can be repressed by different tRNA genes placed upstream at varied distances in both orientations.To test whether this phenomenon functions in naturally occurring instances in which tRNA genes and pol II promoters are juxtaposed, we examined the sigma and Ty3 elements. This class of retrotransposons is always found integrated immediately upstream of different tRNA genes. Weakening tRNA gene transcription by means of a temperature-sensitive mutation in RNA pol III increases the pheromone-inducible expression of sigma and Ty3 elements up to 60-fold.Many eukaryotic genomes contain families of moderately to highly repeated DNA elements containing RNA polymerase III (pol III) promoters (reviewed in references 74 and 75). Frequently these elements resemble the intragenic pol III promoter class found in tRNA and 7SL RNA genes, which consist of consensus A-box and B-box sequences downstream from the transcription start sites. These elements can be found either dispersed as individual copies or as highly reiterated tandem copies, especially in heterochromatic regions. The pol III elements are not generally transcribed into stable RNA commensurate with their copy number in vivo, although they can usually be transcribed in vitro, and there are numerous reports of condition-specific or development-specific activation in vivo (10,27,61,90,95,97,101). Several hypotheses have been put forward regarding possible functions for these sequences, but one particularly interesting suggestion is that dispersed RNA pol III promoters might exert either a positive or negative influence on the transcriptional activity of overlapping or nearby RNA pol II promoters (11,12,15,89,90,96). In some cases, cryptic pol III promoter elements directly interfere with factor binding sites in the pol II promoter upstream region or with the pol II initiation site itself. In at least one report, however, repression was achieved by an Alu repetitive element, in which case there was no obvious steric overlap with the neighboring pol II promoter (96).In this report, the question of whether RNA pol III promoters can exert negative transcriptional regulation on neighboring DNA has been approached by studying the budding yeast Saccharomyces cerevisiae. Although this yeast does not appear to have any Alu-ty...

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supporting

confidence: 76%

tRNA genes as transcriptional repressor elements.

Hull¹,

Erickson²,

Johnston³

et al. 1994

Mol. Cell. Biol.

120

129

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“…(i) Template commitment assays show that TFIIIB is stably sequestered by preformed TFIIIC-template complexes (1,45). (ii) Transcription is severely impaired if exotic proteins are permitted to bind within upstream regions corresponding to the binding site of yeast TFIIIB (9,28,31,54). The principal difficulty in detecting TFIIIB-DNA complexes directly may be due to low concentrations of the required factors.…”

Section: Discussionmentioning

confidence: 99%

Silkworm TFIIIB Binds both Constitutive and Silk Gland-Specific tRNA^Ala Promoters but Protects Only the Constitutive Promoter from DNase I Cleavage

Young

Ahnert

Sprague

1996

Molecular and Cellular Biology

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We have identified a complex between TFIIIB and the upstream promoter of silkworm tRNA Ala genes that is detectable by gel retardation and DNase I footprinting. Formation of this complex depends on the integrity of previously identified upstream promoter elements and on the presence of other silkworm transcription factors, either TFIIID or a fraction that contains both TFIIIC and TFIIID. We have used this complex to compare the interactions of TFIIIB with two kinds of tRNA Ala genes whose different in vitro transcription properties are conferred by the upstream segments of their promoters. These are the tRNA C Ala genes, which are transcribed constitutively, and the tRNA SG Ala genes, which are transcribed only in the silk gland. We find that TFIIIB binds tRNA SG Ala genes with lower affinity than it binds tRNA C Ala genes. In addition, the TFIIIB complexes formed on tRNA SG Ala genes differ qualitatively from those formed on tRNA C Ala genes. Both the transcriptional activity of tRNA SG Ala complexes and the ability of the complexes to protect upstream DNA from DNase I digestion are reduced.

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“…The observation that Ty insertions frequently take place upstream of tRNA genes in yeast cells (16,19) and Dictyostelium discoideum (35), for example, may reflect in part the presence of a nucleosome-free domain upstream of these genes. Other processes involving DNA as a template, such as recombination and repair (59), may also be facilitated for sequences close to expressed genes which are consequently not packaged into chromatin.…”

Section: Discussionmentioning

confidence: 99%

A transcriptionally active tRNA gene interferes with nucleosome positioning in vivo.

Morse¹,

Roth²,

Simpson³

1992

Mol. Cell. Biol.

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Transfer RNA Genes: Landmarks for Integration of Mobile Genetic Elements in Dictyostelium discoideum

Cited by 61 publications

References 16 publications

tRNA genes as transcriptional repressor elements.

tRNA genes as transcriptional repressor elements.

Silkworm TFIIIB Binds both Constitutive and Silk Gland-Specific tRNA^Ala Promoters but Protects Only the Constitutive Promoter from DNase I Cleavage

A transcriptionally active tRNA gene interferes with nucleosome positioning in vivo.

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Transfer RNA Genes: Landmarks for Integration of Mobile Genetic Elements in Dictyostelium discoideum

Cited by 61 publications

References 16 publications

tRNA genes as transcriptional repressor elements.

tRNA genes as transcriptional repressor elements.

Silkworm TFIIIB Binds both Constitutive and Silk Gland-Specific tRNAAla Promoters but Protects Only the Constitutive Promoter from DNase I Cleavage

A transcriptionally active tRNA gene interferes with nucleosome positioning in vivo.

Contact Info

Product

Resources

About

Silkworm TFIIIB Binds both Constitutive and Silk Gland-Specific tRNA^Ala Promoters but Protects Only the Constitutive Promoter from DNase I Cleavage