Recombinant 43-kDa USF binds to DNA and activates transcription in a manner indistinguishable from that of natural 43/44-kDa USF.
USF is a cellular factor involved in the transcriptional regulation of several cellular and viral promoters. Purified USF from HeLa cells (HeLa USF) consists of 43- and 44-kDa polypeptides which show independent binding to a specific DNA element. A cDNA encoding the 43-kDa species has been previously cloned. We show here that the purified form of bacterially expressed 43-kDa USF (i) exists in solution as a dimer whose formation is greatly favored under reducing conditions, (ii) binds to its cognate DNA sequence in a manner indistinguishable from that of HeLa USF, and (iii) is as efficient as HeLa USF in stimulating transcription from target promoters in a reconstituted cell-free system. Additional data indicate that the 44-kDa component of HeLa USF is immunologically unrelated to the 43-kDa polypeptide but is associated with it in HeLa cell extracts. These results suggest that the 43-kDa component possesses an intrinsic DNA binding and transcriptional activation potential and that the 44-kDa USF component of the natural USF complex may have some regulatory role.
Pognonec
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Rockefeller University, New York, New York 10021-6399.
Roeder
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D001483:Base Sequence; D015153:Blotting, Western; D002474:Cell-Free System; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000502:physiology; D011994:Recombinant Proteins / Q000378:metabolism; D013604:T-Phages / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology; D051720:Upstream Stimulatory Factors
D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D014157:Transcription Factors; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors; D004247:DNA