DNA-binding properties of phosphorylated and dephosphorylated D2-T antigen, a simian-virus-40 T-antigen-related protein.
I have examined the role of phosphorylation of D2-T antigen in its DNA-binding properties and ATPase activity. Treatment of partially purified D2-T antigen with alkaline phosphatase resulted in removal of maximally 90% of the phosphate label associated with the radio-labeled protein. The specific and nonspecific DNA-binding properties of partially dephosphorylated D2-T antigen were identical to those of the untreated control. In contrast, acid phosphatase was able to dephosphorylate D2-T antigen quantitatively. The general affinity for DNA of the completely dephosphorylated protein was unchanged or eventually slightly increased. However, its specific affinity for a restriction fragment containing the canonical T-antigen-binding sites was drastically reduced as shown by competition with unlabeled salmon sperm DNA. The results imply that nonspecific DNA binding of D2-T antigen is unaffected by phosphorylation whereas a specific phosphorylation site seems to be involved in the formation and/or stabilization of the specific protein-DNA complex. On the other hand, the ATPase activity of D2-T antigen seems to be unaffected by the degree of phosphorylation.
Baumann
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D000135:Acid Phosphatase; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor / Q000032:analysis* / Q000378:metabolism*; D001483:Base Sequence; D055598:Chemical Phenomena; D002621:Chemistry; D003101:Collodion; D004279:DNA, Viral / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D013539:Simian virus 40 / Q000276:immunology*; D014764:Viral Proteins / Q000378:metabolism*
D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor; D004279:DNA, Viral; D014764:Viral Proteins; D003101:Collodion; D000135:Acid Phosphatase; D000251:Adenosine Triphosphatases