Identification of transcriptional elements within the long terminal repeat of Rous sarcoma virus

1983 ◽  
Vol 3 (10) ◽  
pp. 1834-1845
Author(s):  
G M Gilmartin ◽  
J T Parsons

Transcriptional regulatory elements within the Rous sarcoma virus long terminal repeat were examined by the construction of a series of deletions and small insertions within the U3 region of the long terminal repeat. The analysis of these mutations in chicken embryo cells and COS cells permitted the identification of important transcriptional regulatory elements. Sequences within the region 31 to 18 base pairs upstream of the RNA cap site (-31 to -18), encompassing a TATA box-like sequence, function in the selection of the correct site of transcription initiation and, in addition, augment the efficiency of transcription. These sequences are essential for virus replication. Sequences within the region -79 to -59, overlapping a CAAT box-like sequence, are not required for virus replication and have no obvious effect on viral RNA transcription in the presence of an intact TATA box. However, in mutants lacking a functional TATA sequence, mutations in this region serve to decrease the efficiency of correct transcriptional initiation events.

1983 ◽  
Vol 3 (10) ◽  
pp. 1834-1845 ◽  
Author(s):  
G M Gilmartin ◽  
J T Parsons

Transcriptional regulatory elements within the Rous sarcoma virus long terminal repeat were examined by the construction of a series of deletions and small insertions within the U3 region of the long terminal repeat. The analysis of these mutations in chicken embryo cells and COS cells permitted the identification of important transcriptional regulatory elements. Sequences within the region 31 to 18 base pairs upstream of the RNA cap site (-31 to -18), encompassing a TATA box-like sequence, function in the selection of the correct site of transcription initiation and, in addition, augment the efficiency of transcription. These sequences are essential for virus replication. Sequences within the region -79 to -59, overlapping a CAAT box-like sequence, are not required for virus replication and have no obvious effect on viral RNA transcription in the presence of an intact TATA box. However, in mutants lacking a functional TATA sequence, mutations in this region serve to decrease the efficiency of correct transcriptional initiation events.


2000 ◽  
Vol 74 (14) ◽  
pp. 6511-6519 ◽  
Author(s):  
Constance M. Mobley ◽  
Linda Sealy

ABSTRACT Many viral genes contain core promoters with two basal control elements, the TATA box and the pyrimidine-rich initiator (Inr). However, the molecular mechanisms involved in transcription initiation from composite core promoters (TATA+ Inr+) containing Inr elements are unclear. The Rous sarcoma virus (RSV) long terminal repeat (LTR) contains a transcriptionally potent enhancer and core promoter composed of a TATA box and an Inr-like sequence, termed the transcription start site core (TSSC). Previously we demonstrated that the TSSC binds the multifunctional Inr-binding protein YY1. Here we present evidence that the TSSC also binds the multifunctional transcription factor TFII-I and that both TFII-I and YY1 are required for RSV LTR transcriptional activity. Gel shift assays using anti-TFII-I antibody show that TFII-I is present in a protein complex that specifically binds to the TSSC. Mutations in the TSSC that reduce TFII-I binding also reduce RSV LTR enhancer and promoter activity. Transient-transfection assays demonstrate that TFII-I transactivates the RSV LTR from ca. fourfold (basal) to ca. sevenfold (enhanced) in both human and natural host cell lines. Importantly, the activity of the TSSC element can be attributed to the binding activity of TFII-I and the YY1 protein, since mutation of each of these binding sites within the TSSC element abolishes all viral expression as demonstrated by transient-transfection assays. Taken together, these data demonstrate that expression of RSV viral mRNA is dependent on both TFII-I and YY1.


Cell ◽  
1980 ◽  
Vol 22 (3) ◽  
pp. 787-797 ◽  
Author(s):  
Tadashi Yamamoto ◽  
Benoit de Crombrugghe ◽  
Ira Pastan

1987 ◽  
Vol 7 (2) ◽  
pp. 787-798 ◽  
Author(s):  
L Sealey ◽  
R Chalkley

We used the sensitive gel electrophoresis DNA-binding assay and DNase I footprinting to detect at least two protein factors (EFI and EFII) that bound specifically to the Rous sarcoma virus (RSV) enhancer in vitro. These factors were differentially extracted from quail cell nuclei, recognized different nucleotide sequences in the U3 region of the RSV long terminal repeat, and appeared to bind preferentially to opposite DNA strands as monitored by the DNase I protection assay. The EFI- and EFII-protected regions within U3 corresponded closely to sequences previously demonstrated by deletion mutagenesis to be required for enhancer activity, strongly suggesting a functional significance for these proteins. Only weak homologies between other enhancer consensus sequence motifs and the EFI and EFII recognition sites were observed, and other viral enhancers from simian virus 40 and Moloney murine sarcoma virus did not compete effectively with the RSV enhancer for binding either factor.


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