Loss of DNA-binding and new transcriptional trans-activation function in polyomavirus large T-antigen with mutation of zinc finger motif.
A putative zinc finger in polyomavirus large T-antigen was investigated. We were unable to demonstrate unequivocally a requirement for zinc in specific DNA-binding using the chelating agent 1, 10-phenanthroline. An involvement of the putative zinc finger in specific DNA-binding was nevertheless suggested by the properties of a mutant protein with a cys----ser replacement in the finger motif. Probably as a result of the defective DNA-binding, the mutant protein had lost its activity in initiation of viral DNA-replication and in negative regulation of viral early transcription. However, the trans-activation of the viral late promoter was normal. The analysis also revealed a previously unrecognized activity of large T-antigen. The mutant protein trans-activated the viral early promoter. In the wild-type protein this activity is probably concealed by the separate, negative regulatory function.
Bergqvist
A
A
Department of Medical Virology, Uppsala University Biomedical Center, Sweden.
Nilsson
M
M
Bondeson
K
K
Magnusson
G
G
D000595:Amino Acid Sequence; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008667:Metalloproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010618:Phenanthrolines / Q000494:pharmacology; D011120:Polyomavirus / Q000276:immunology*; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D015032:Zinc
D000952:Antigens, Polyomavirus Transforming; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D008667:Metalloproteins; D010618:Phenanthrolines; D015032:Zinc