An upstream signal is required for in vitro transcription ofNeurospora 5S RNA genes

Selker, Eric U.; Morzycka-Wroblewska, Ewa; Stevens, Judith N.; Metzenberg, Robert L.

doi:10.1007/bf02428052

Cited by 58 publications

(32 citation statements)

References 31 publications

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“…The tRNA genes used in these experiments do share a TATA-like motif (Fig. 6B) at positions that are comparable with that of the Neiurospora SS rRNA gene CATAT upstream promoter element (60,67). However, it is doubtful that a TATA motif is essential for tRNA gene transcription in yeast cells, since it can be deleted in the SUP4 tRNA gene (62).…”

Section: Resultsmentioning

confidence: 93%

Transcription factor IIIB generates extended DNA interactions in RNA polymerase III transcription complexes on tRNA genes.

et al. 1989

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Transcription complexes that assemble on tRNA genes in a crude Saccharomyces cerevisiae cell extract extend over the entire transcription unit and approximately 40 base pairs of contiguous 5'-flanking DNA. We show here that the interaction with 5'-flanking DNA is due to a protein that copurifies with transcription factor TFIIIB through several steps of purification and shares characteristic properties that are normally ascribed to TFIIIB: dependence on prior binding of TFIIIC and great stability once the TFIIIC-TFIIIB-DNA complex is formed. SUP4 gene (tRNATyr) DNA that was cut within the 5'-flanking sequence (either 31 or 28 base pairs upstream of the transcriptional start site) was no longer able to stably incorporate TFIIIB into a transcription complex. The TFIIIB-dependent 5'-flanking DNA protein interaction was predominantly not sequence specific. The extension of the transcription complex into this DNA segment does suggest two possible explanations for highly diverse effects of flanking-sequence substitutions on tRNA gene transcription: either (i) proteins that are capable of binding to these upstream DNA segments are also potentially capable of stimulating or interfering with the incorporation of TFIIIB into transcription complexes or (ii) 5'-flanking sequence influences the rate of assembly of TFIIIB into stable transcription complexes.Specific transcription by RNA polymerase III (Pol III) requires the participation of multiple transcription factors. With the exception of the U6 and 7SK RNA genes (7, 14, 17. 41. 50, 53), the DNA-binding sites that anchor these factors are located within transcription units. It is a remarkable property of Pol III that it can transcribe through the bulky transcription complexes that are built up on these internal promoters (also called internal control regions) without dispersing them (69).Specific initiation of transcription at tRNA genes, with which this paper primarily deals, requires factors TFIIIB and -C. Although the yeast analog of TFIIIC (also called T) has been relatively highly purified as a single component (54: see below), HeLa TFIIIC splits into two components upon purification: C2 is the primary DNA-binding determinant, and Cl either modifies the binding properties of C2 or binds to DNA in a C2-dependent manner (12,18,71). Both HeLa C2 factor and yeast TFIIIC (T) are large (12,54,64). The Bonbvx moni tRNA gene transcription factors can also be separated into three fractions, whose relationship to TFIIIB, Cl, and C2 remains to be established (51).The first promoter dissections of Pol III genes identified essential gene-internal elements (10,19,25,55) and implied that flanking DNA sequence was almost without effect on promoter strength. The general situation with regard to the effects of flanking sequence on promoter strength of Pol III genes is, however, diverse, and this fact has only gradually been recognized (3, 4, 20, 29, 52, 62, 63; tions with very substantial effects have been reported. Flanking sequences affecting promoter strength are located within ...

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Section: Resultsmentioning

confidence: 93%

Transcription factor IIIB generates extended DNA interactions in RNA polymerase III transcription complexes on tRNA genes.

et al. 1989

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“…Kassavetis et al {1989} andBraun et al {1989} have shown that the analogous region of tRNA and 5S rRNA genes is bound by TFIIIB in a TFIIIC-dependent fashion. Although many tRNA and 5S rRNA genes do not exhibit a strong upstream sequence dependence, suggesting that TFIIIB can bind in a sequence-independent manner, TATA-like sequences are often present -3 0 bp upstream of tRNA and 5S rRNA genes, and, in some cases, are absolutely required for promoter function (Larson et al 1983;Selker et al 1986;Garcia et al 1987}. Furthermore, movement of the TATA-like sequence with respect to the coding region of a Neurospora 5S rRNA gene can result in a corresponding shift in the transcriptional start site {Tyler…”

Section: Implications For U6 Genes In Other Organismsmentioning

confidence: 99%

Transcription of a yeast U6 snRNA gene requires a polymerase III promoter element in a novel position.

Brow¹,

Guthrie²

1990

Genes Dev.

149

162

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Vertebrate genes coding for U6 small nuclear RNA are transcribed by RNA polymerase III (pol III), using only upstream promoter elements rather than the A and B block internal control regions typical of most pol III transcription units. We show that expression of the U6 gene from the yeast Saccharomyces cerevisiae has two unexpected features: it requires a B block promoter element, and this element is located in a novel position, 120 bp downstream of the coding region. In tRNA genes, the B block is the primary binding site for transcription factor (TF) IIIC, whose function is to promote the subsequent binding of TFIIIB. Both factors are thus implicated in yeast U6 gene transcription. We present a model of the U6 transcription complex based on the structure of yeast and vertebrate U6 promoters.

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“…Nevertheless, the 5S rRNA regions of the majority of the genes are identical, matching the a 5S rRNA. Outside of the 5S rRNA coding region, all of the dispersed 5S rRNA genes are radically different, with the exception of a TATA box located upstream of the transcription start site (13,21). Tandemly arranged 5S rRNA genes in other organisms are apparently homogeneous, presumably because of homogenization by unequal crossing over (26).…”

mentioning

confidence: 99%

A natural case of RIP: degeneration of the DNA sequence in an ancestral tandem duplication.

Grayburn¹,

Selker²

1989

Mol. Cell. Biol.

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5S rRNA genes of Neurospora crassa are generally dispersed in the genome and are unmethylated. The t-q region of Oak Ridge strains represents an informative exception. Most of the cytosines in this region, which consists of a diverged tandem duplication of a 0.8-kilobase-pair segment including a 5S rRNA gene, appear to be methylated (E. U. Selker and J. N. Stevens, Proc. Natl. Acad. Sci. USA 82:8114-8118, 1985 Eucaryotic genomes contain both tandemly arranged and dispersed repeated sequences. For example, the genome of Neurospora crassa includes approximately 200 tandemly arranged copies of a DNA segment specifying the 17S, 5.8S, and 25S rRNAs and approximately 100 dispersed copies of 5S rRNA genes (6,12,26). Curiously, in most organisms, 5S rRNA genes appear to be tandemly arranged. We have been interested in (i) why some repeated genes of an organism are dispersed while others are tandemly arranged and (ii) whether the arrangement of repeated genes can have important consequences for an organism. To approach these questions, we have studied the 5S rRNA gene family of N. crassa (12,13,18,26). Neurospora 5S rRNA can be fractionated into at least 12 different species (24), and genes corresponding to a number of these 5S rRNAs have been identified (12,26). The various 5S rRNAs of N. crassa are remarkably different. For example, the most abundant RNA, a, differs from the second most abundant species, 3, at 15 positions in the 120-nucleotide RNA. The different 5S rRNA genes do not appear to be differentially regulated (24). Presumably, the dispersed arrangement of the genes allowed for their divergence (26). Nevertheless, the 5S rRNA regions of the majority of the genes are identical, matching the a 5S rRNA. Outside of the 5S rRNA coding region, all of the dispersed 5S rRNA genes are radically different, with the exception of a TATA box located upstream of the transcription start site (13, 21). Tandemly arranged 5S rRNA genes in other organisms are apparently homogeneous, presumably because of homogenization by unequal crossing over (26). Although dispersed * Corresponding author. t Present address:

show abstract

An upstream signal is required for in vitro transcription ofNeurospora 5S RNA genes

Cited by 58 publications

References 31 publications

Transcription factor IIIB generates extended DNA interactions in RNA polymerase III transcription complexes on tRNA genes.

Transcription factor IIIB generates extended DNA interactions in RNA polymerase III transcription complexes on tRNA genes.

Transcription of a yeast U6 snRNA gene requires a polymerase III promoter element in a novel position.

A natural case of RIP: degeneration of the DNA sequence in an ancestral tandem duplication.

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