Mammalian beta-polymerase promoter: phosphorylation of ATF/CRE-binding protein and regulation of DNA binding.
The gene for the mammalian DNA repair enzyme DNA polymerase beta (beta-pol) is constitutively expressed in most cells, but is regulated in a tissue-specific fashion and can be induced in response to some types of DNA damaging agents. The promoter for the human beta-pol gene has been characterized and found to be TATA-less, but it does have multiple GC boxes and one ATF/CRE-binding site located within 50 residues 5' of the major mRNA start site. The ATF/CRE-binding site has been found to be essential for activity of the cloned promoter. We report that a bovine testes DNA-binding protein with specificity for the beta-pol promoter ATF/CRE-binding site is phosphorylated in vivo and contains several phosphorylation sites. Sequence specific DNA-binding by the purified protein is reduced when the natural protein is dephosphorylated or when it is hyperphosphorylated by protein kinase A (cKA) in vitro. These results suggest the possibility that phosphorylation systems may change binding of this ATF/CRE-binding protein to the beta-pol promoter and in turn modulate the promoter. Possible correlation of the results with transient expression activity of the cloned beta-pol promoter fusion gene was obtained in 293 cells. Cotransfection with a cKA expression plasmid to elevate phosphorylation was found to strongly reduce promoter activity.
Englander
E W
EW
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Widen
S G
SG
Wilson
S H
SH
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein; D004247:DNA / Q000378:metabolism; D004256:DNA Polymerase I / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D013737:Testis / Q000378:metabolism
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D004247:DNA; D004256:DNA Polymerase I