scholarly journals RNA polymerase III-mediated transcription of the trypanosome U2 small nuclear RNA gene is controlled by both intragenic and extragenic regulatory elements.

1994 ◽  
Vol 14 (3) ◽  
pp. 2021-2028 ◽  
Author(s):  
A Fantoni ◽  
A O Dare ◽  
C Tschudi

Transcription of U2 small nuclear RNA (snRNA) genes in eukaryotes is executed by RNA polymerase II and is dependent on extragenic cis-acting regulatory sequences which are not found in other genes. Here we have mapped promoter elements of the Trypanosoma brucei U2 snRNA gene by transient DNA expression of mutant constructs in insect form trypanosomes. Unlike other eukaryotic U2 snRNA genes, the T. brucei homolog is transcribed by an RNA polymerase III-like enzyme on the basis of its sensitivity to the inhibitors alpha-amanitin and tagetitoxin. Thus, the trypanosome U2 snRNA provides a unique example of an RNA polymerase III transcript carrying a trimethylated cap structure. The promoter of this gene consists of three distinct elements: an intragenic sequence close to the 5' end of the coding region, which is probably required to position the polymerase at the correct transcription start site; and two extragenic elements, located 110 and 160 nucleotides upstream, which are essential for U2 snRNA gene expression. These two elements closely resemble both in sequence and in distance from each other the A and B box consensus sequences of the internal control regions of tRNA genes.

1994 ◽  
Vol 14 (3) ◽  
pp. 2021-2028
Author(s):  
A Fantoni ◽  
A O Dare ◽  
C Tschudi

Transcription of U2 small nuclear RNA (snRNA) genes in eukaryotes is executed by RNA polymerase II and is dependent on extragenic cis-acting regulatory sequences which are not found in other genes. Here we have mapped promoter elements of the Trypanosoma brucei U2 snRNA gene by transient DNA expression of mutant constructs in insect form trypanosomes. Unlike other eukaryotic U2 snRNA genes, the T. brucei homolog is transcribed by an RNA polymerase III-like enzyme on the basis of its sensitivity to the inhibitors alpha-amanitin and tagetitoxin. Thus, the trypanosome U2 snRNA provides a unique example of an RNA polymerase III transcript carrying a trimethylated cap structure. The promoter of this gene consists of three distinct elements: an intragenic sequence close to the 5' end of the coding region, which is probably required to position the polymerase at the correct transcription start site; and two extragenic elements, located 110 and 160 nucleotides upstream, which are essential for U2 snRNA gene expression. These two elements closely resemble both in sequence and in distance from each other the A and B box consensus sequences of the internal control regions of tRNA genes.


1987 ◽  
Vol 262 (1) ◽  
pp. 75-81
Author(s):  
R Reddy ◽  
D Henning ◽  
G Das ◽  
M Harless ◽  
D Wright

1994 ◽  
Vol 14 (9) ◽  
pp. 5910-5919
Author(s):  
S Connelly ◽  
C Marshallsay ◽  
D Leader ◽  
J W Brown ◽  
W Filipowicz

RNA polymerase (Pol) II- and RNA Pol III-transcribed small nuclear RNA (snRNA) genes of dicotyledonous plants contain two essential upstream promoter elements, the USE and TATA. The USE is a highly conserved plant snRNA gene-specific element, and its distance from the -30 TATA box, corresponding to approximately three and four helical DNA turns in Pol III and Pol II genes, respectively, is crucial for determining RNA Pol specificity of transcription. Sequences upstream of the USE play no role in snRNA gene transcription in dicot plants. Here we show that for expression of snRNA genes in maize, a monocotyledonous plant, the USE and TATA elements are essential, but not sufficient, for transcription. Efficient expression of both Pol II- and Pol III-specific snRNA genes in transfected maize protoplasts requires an additional element(s) positioned upstream of the USE. This element, named MSP (for monocot-specific promoter; consensus, RGCCCR), is present in one to three copies in monocot snRNA genes and is interchangeable between Pol II- and Pol III-specific genes. The efficiency of snRNA gene expression in maize protoplast is determined primarily by the strength of the MSP element(s); this contrasts with the situation in protoplasts of a dicot plant, Nicotiana plumbaginifolia, where promoter strength is a function of the quality of the USE element. Interestingly, the organization of monocot Pol III-specific snRNA gene promoters closely resembles those of equivalent vertebrate promoters. The data are discussed in the context of the coevolution of Pol II- and Pol III-specific snRNA gene promoters within many eukaryotic organisms.


1992 ◽  
Vol 12 (7) ◽  
pp. 3247-3261
Author(s):  
S Murphy ◽  
J B Yoon ◽  
T Gerster ◽  
R G Roeder

The promoters of both RNA polymerase II- and RNA polymerase III-transcribed small nuclear RNA (snRNA) genes contain an essential and highly conserved proximal sequence element (PSE) approximately 55 bp upstream from the transcription start site. In addition, the upstream enhancers of all snRNA genes contain binding sites for octamer-binding transcription factors (Octs), and functional studies have indicated that the PSE and octamer elements work cooperatively. The present study has identified and characterized a novel transcription factor (designated PTF) which specifically binds to the PSE sequence of both RNA polymerase II- and RNA polymerase III-transcribed snRNA genes. PTF binding is markedly potentiated by Oct binding to an adjacent octamer site. This potentiation is effected by Oct-1, Oct-2, or the conserved POU domain of these factors. In agreement with these results and despite the independent binding of Octs to the promoter, PTF and Oct-1 enhance transcription from the 7SK promoter in an interdependent manner. Moreover, the POU domain of Oct-1 is sufficient for significant in vitro activity in the presence of PTF. These results suggest that essential activation domains reside in PTF and that the potentiation of PTF binding by Octs plays a key role in the function of octamer-containing snRNA gene enhancers.


1986 ◽  
Vol 83 (22) ◽  
pp. 8575-8579 ◽  
Author(s):  
G. R. Kunkel ◽  
R. L. Maser ◽  
J. P. Calvet ◽  
T. Pederson

1992 ◽  
Vol 12 (7) ◽  
pp. 3247-3261 ◽  
Author(s):  
S Murphy ◽  
J B Yoon ◽  
T Gerster ◽  
R G Roeder

The promoters of both RNA polymerase II- and RNA polymerase III-transcribed small nuclear RNA (snRNA) genes contain an essential and highly conserved proximal sequence element (PSE) approximately 55 bp upstream from the transcription start site. In addition, the upstream enhancers of all snRNA genes contain binding sites for octamer-binding transcription factors (Octs), and functional studies have indicated that the PSE and octamer elements work cooperatively. The present study has identified and characterized a novel transcription factor (designated PTF) which specifically binds to the PSE sequence of both RNA polymerase II- and RNA polymerase III-transcribed snRNA genes. PTF binding is markedly potentiated by Oct binding to an adjacent octamer site. This potentiation is effected by Oct-1, Oct-2, or the conserved POU domain of these factors. In agreement with these results and despite the independent binding of Octs to the promoter, PTF and Oct-1 enhance transcription from the 7SK promoter in an interdependent manner. Moreover, the POU domain of Oct-1 is sufficient for significant in vitro activity in the presence of PTF. These results suggest that essential activation domains reside in PTF and that the potentiation of PTF binding by Octs plays a key role in the function of octamer-containing snRNA gene enhancers.


2007 ◽  
Vol 282 (38) ◽  
pp. 27887-27896 ◽  
Author(s):  
Liping Gu ◽  
Rhonda Husain-Ponnampalam ◽  
Susanne Hoffmann-Benning ◽  
R. William Henry

Human U6 small nuclear RNA gene transcription by RNA polymerase III requires the general transcription factor SNAPC, which binds to human small nuclear RNA core promoter elements and nucleates pre-initiation complex assembly with the Brf2-TFIIIB complex. Multiple components in this pathway are phosphorylated by the protein kinase CK2, including the Bdp1 subunit of the Brf2-TFIIIB complex, and RNA polymerase III, with negative and positive outcomes for U6 transcription, respectively. However, a role for CK2 phosphorylation of SNAPC in U6 transcription has not been defined. In this report, we investigated the role of CK2 in modulating the transcriptional properties of SNAPC and demonstrate that within SNAPC, CK2 phosphorylates the N-terminal half of the SNAP190 subunit at two regions (amino acids 20-63 and 514-545) that each contain multiple CK2 consensus sites. SNAP190 phosphorylation by CK2 inhibits both SNAPC DNA binding and U6 transcription activity. Mutational analyses of SNAP190 support a model wherein CK2 phosphorylation triggers an allosteric inhibition of the SNAP190 Myb DNA binding domain.


1994 ◽  
Vol 14 (9) ◽  
pp. 5910-5919 ◽  
Author(s):  
S Connelly ◽  
C Marshallsay ◽  
D Leader ◽  
J W Brown ◽  
W Filipowicz

RNA polymerase (Pol) II- and RNA Pol III-transcribed small nuclear RNA (snRNA) genes of dicotyledonous plants contain two essential upstream promoter elements, the USE and TATA. The USE is a highly conserved plant snRNA gene-specific element, and its distance from the -30 TATA box, corresponding to approximately three and four helical DNA turns in Pol III and Pol II genes, respectively, is crucial for determining RNA Pol specificity of transcription. Sequences upstream of the USE play no role in snRNA gene transcription in dicot plants. Here we show that for expression of snRNA genes in maize, a monocotyledonous plant, the USE and TATA elements are essential, but not sufficient, for transcription. Efficient expression of both Pol II- and Pol III-specific snRNA genes in transfected maize protoplasts requires an additional element(s) positioned upstream of the USE. This element, named MSP (for monocot-specific promoter; consensus, RGCCCR), is present in one to three copies in monocot snRNA genes and is interchangeable between Pol II- and Pol III-specific genes. The efficiency of snRNA gene expression in maize protoplast is determined primarily by the strength of the MSP element(s); this contrasts with the situation in protoplasts of a dicot plant, Nicotiana plumbaginifolia, where promoter strength is a function of the quality of the USE element. Interestingly, the organization of monocot Pol III-specific snRNA gene promoters closely resembles those of equivalent vertebrate promoters. The data are discussed in the context of the coevolution of Pol II- and Pol III-specific snRNA gene promoters within many eukaryotic organisms.


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