A nuclear matrix protein binds very tightly to DNA in the avian beta-globin gene enhancer.
Current evidence suggests that DNA is covalently attached to proteins in the nuclear matrix of eukaryotic cells and that specific DNA sequences are tightly associated with the nuclear matrix. However, it has not been documented that specific DNA sequences can become covalently attached to nuclear matrix protein. We have examined the binding of cloned DNA sequences that contain the avian beta-globin gene enhancer, a region previously shown to be matrix associated in erythroid cells in vivo, with nuclear matrices from several avian tissue sources to determine if covalent DNA-protein bonds are formed. Our results indicate that sequence-specific DNA-protein complexes that are resistant to denaturation by SDS, boiling, and phenol and disulfide reduction are formed. Excess protein, capable of forming very tight bonds with DNA that contains the beta-globin gene enhancer, is present in cells in which matrix attachment of this DNA sequence is not detected in vivo. Evidence is presented that suggests that the protein to which DNA forms very tight bonds is not topoisomerase II. These results are discussed in relation to current models of the nuclear matrix and the utility of in vitro assays of matrix attachment regions using cloned DNA.
Zenk
D W
DW
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
Ginder
G D
GD
Brotherton
T W
TW
D000818:Animals; D001667:Binding, Competitive; D002645:Chickens / Q000235:genetics; D002874:Chromosome Mapping; D004247:DNA / Q000378:metabolism; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic / Q000235:genetics; D004912:Erythrocytes / Q000378:metabolism; D005914:Globins / Q000235:genetics*; D015530:Nuclear Matrix / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D009928:Organ Specificity / Q000235:genetics
D015342:DNA Probes; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D005914:Globins; D004247:DNA