Properties of BGP1, a poly(dG)-binding protein from chicken erythrocytes

Abstract

The chicken beta A-globin gene contains in the neighborhood of its 5' promoter a (dG)-homopolymer sequence 16 base pairs long. The 66 kD protein BGP1 (beta globin protein 1), isolated from chicken erythrocytes, has been shown to bind specifically to this sequence. We describe further purification of BGP1, measure its affinity for the beta A-globin promoter binding site, and analyze its binding properties. The minimal binding sequence is seven dG residues; methylation interference studies show that each of these residues contacts BGP1. Binding competition experiments employing (dG).(dC) oligomers of varying lengths also consistent with (dG)7 as a minimum recognition sequence. All of the data can be explained by a model in which BGP1 binds to any contiguous set of seven (dG) residues, so that the effective constant for binding to (dG)n is proportional to n minus 6. This behavior may be typical of proteins that bind specifically to repeated sequences.

Identification of a key regulatory element for the basal activity of the human insulin-like growth factor II gene promoter P3

“…In the chicken, two G-string-element-containing promoters have been described that are bound by the chicken erythrocyte protein called β-globin protein 1, BGP 1 [23,24]. In the sea urchin (Psammechinus miliaris) the purification of another G-stringbinding protein of 59.5 kDa, called sea-urchin G-string factor 1 (suGF1), has been described [25,26].…”

Vezf1 protein binding sites genome-wide are associated with pausing of elongating RNA polymerase II

“…Early interest in these proteins was related both to the unusual stability and conformational properties of the homopolymer duplexes that are their targets, and to their association with potential regulatory sites in the promoters of the chicken adult β-globin promoter and the sea urchin gene LpS1, which bind the factors β-globin protein 1 (BGP1) and sea urchin G-string binding factor 1, respectively (1,2). Recently, we have begun to reinvestigate the role of BGP1 as a regulatory factor because of our identification of BGP1 binding sites (3) within the compound insulator element at the 5′ end of the chicken β Aglobin locus, where they play an essential role (4).…”

Purification and characterization of p27, a protein from hepatocyte chromatin Evidence suggesting that it binds selectively to guanine‐rich single‐stranded DNA

“…First, the ~ 155 and 27 kDa native and denatured molecular sizes, respectively, of p27 differed from those of the 43 and 55 kDa subunit heterodimer telomeric DNA binding protein from Oxytricha nova [14] and from the monomeric 50 kDa telomere binding protein from Euplotes crassus [15]. Likewise, p27 was structurally distinct from the hepatic 37 kDa telomeric polypeptide, sTBP [16], and from the 66 kDa chicken erythrocyte poly(dG) binding protein, BGP1 [6,17]. Second, the DNA binding specificity of p27 differed from those of most other guanine-rich DNA binding proteins.…”

“…Guanine-rich clusters appear in DNA at multiple locations in the genome such as telomers [1][2][3], regulatory regions of various genes [4][5][6], variable number of tandem repeats (VNTR) minisatellites [7,8], and the immunoglobulin switch region [9]. Some of these stretches possess the potential to form unusual structures, such as triple helix at (dG), -(dC), tracts [10,11], or tetrahelical DNA at regions of short runs of contiguous guanine residues [12,13].…”