Transcription factor LSF binds two variant bipartite sites within the SV40 late promoter.

Abstract

The HeLa transcription factor LSF has been purified by heparin-agarose and DNA affinity chromatography, and its DNA binding and transcription properties have been characterized. LSF is a 63-kD polypeptide that binds to two distinct bipartite sites within the SV40 promoter region. One binding site consists of GC motifs 2 and 3 within the 21-bp repeats (LSF-GC site), and the other consists of sequences centered 44 bp upstream of the major late initiation site, L325 (LSF-280 site). Four guanine residues within the LSF-GC site, when methylated, strongly interfere with LSF binding. Alteration of the spacing, but not the sequence, between the two directly repeated GC motifs dramatically reduces the binding affinity of LSF for the site. Thus, LSF appears to recognize directly repeated GC motifs, when their center-to-center distance is 10 bp. The LSF-GC and LSF-280 sites share limited sequence homology. Only half of the LSF-280 site contains a short GC-rich sequence homologous to the GC motif. However, the binding affinity of LSF to the two sites is similar. LSF activates transcription from the SV40 late promoter in vitro from initiation site L325, via its binding to the template DNA. SV40 offers an excellent model system for studying transcriptional regulatory mechanisms in mammalian cells: The virus uses the host cell transcription machinery for expression of its genes, and both biochemical and genetic means can readily be applied in investigating its transcription. During lytic infection, transcription of SV40 is precisely regulated. Before the onset of viral DNA replication, the SV40 early genes (encoding the large-T and small-t antigens) are primarily transcribed; after the onset of viral DNA replication, the SV40 late promoter is activated, and the late genes (encoding the viral capsid proteins) are predominantly expressed (Tooze 1981).The DNA sequences in the SV40 genome that regulate early and late transcription are located within a region of -400 bp (see Fig. 8, below). The SV40 late promoter appears to be very complex and may actually be a combination of multiple overlapping promoters capable of stimulating transcription from the same initiation sites. Many DNA sequence elements have been implicated in promoting late transcription in vivo and/or in vitro. These sequences include the origin of DNA replication (Brady and Khoury 1985;Keller and Alwine 1985), the three 21-bp tandem repeats containing six directly repeated GC motifs (GGGCGG) (Fromm and Berg 1982;Hansen and Sharp 1983;Brady et al. 1984;Hartzell et al. 1984a;Rio and Tjian 1984;Vigneron et al. 1984), the 72-bp direct repeats containing many enhancer elements (Fromm and Berg 1982; Hartzell et al. 1984b;Keller and Alwine 1985; Emoult-Lange et al. 1987), and the region from the 72-bp repeats up to and beyond the major in vivo initiation site, L325 (Brady et al. 1982;Keller and Alwine 1985; Emoult-Lange et al. 1987;Ayer and Dynan 1988). The major late initiation site L325 is not preceded by a typical TATA box (Brady et al. 1982). Environmental factors may...

A Binding Site for the Transcription Factor Grainyhead/Nuclear Transcription Factor-1 Contributes to Regulation of theDrosophila Proliferating Cell Nuclear Antigen Gene Promoter

“…CP2 is identical to LBP-1c/UBP-1, which binds to multiple sites within the human immunodeficiency virus long terminal repeat (57)(58)(59). CP2/LBP-1c/UBP-1 is also identical to the transcription factor LSF that specifically binds to and stimulates transcription from the SV40 major late promoter (60). Interestingly, LSF also binds to sites within the c-fos gene, ornithine decarboxylase gene, and thymidylate synthase gene promoters (61,62).…”

Specific transcription factors stimulate simian virus 40 and polyomavirus origins of DNA replication.

“…SV40 aux-2 consists of three G+C-rich repeats ( Fig. 1) that contain three binding sites for transcription factor Spl (45) or T-ag (25) and one binding site for LSF (42) [21]) and two auxiliary components, aux-J (5210 to between 5193 and 5164) and aux-2 (32 to about 72), whose minimum sequences are defined by deletion analyses (29). The key elements in the promoter region consist of two perfect 21-bp repeats, one imperfect repeat, an A+T-rich region that contains the TATA box, and six G+C-rich sequences that contain the 5'-(G>T)(A>G)GGC-3' recognition sequence for T-ag (0) (25) overlapping the 5'-GGGCGG-3' recognition sequence for Spl (45).…”

Identification and characterization of Grainyhead‐like epithelial transactivator (GET‐1), a novel mammalian Grainyhead‐like factor

“…These are as follows: (1) CP-2 (Lim et al, 1992(Lim et al, , 1993Shirra et al, 1994), also referred to as UBP-1, LSF, LBP-1c, and LBP-1d (alternatively spliced form), a widely expressed transcription factor that has been implicated in activation of the ␣-globin gene (Chodosh et al, 1988;Kim et al, 1990), the HIV-1 long terminal repeat (LTR; Jones et al, 1988;Wu et al, 1988;Malim et al, 1989;Kato et al, 1991), and the SV40 major late promoter (Kim et al, 1987;Huang et al, 1990). This factor can also, depending on context, repress transcription and was shown to cooperate with YY1 to repress HIV-1 LTR activity (Coull et al, 2000); (2) LBP-1a (Sueyoshi et al, 1995), also referred to as LBP-1b (alternatively spliced form) and NF2d9 (Yoon et al, 1994), a widely expressed factor implicated in regulation of the HIV-1 LTR (Yoon et al, 1994) and a P450 gene (Sueyoshi et al, 1995); (3) LBP-9 (Huang and Miller, 2000), also referred to as CP2-related transcriptional Repressor-1 (CRTR-1; Rodda et al, 2001), implicated in regulation of the P450 scc promoter; (4) LBP-32 (Huang and Miller, 2000), also refer- .…”