The ZiN/POZ domain of ZF5 is required for both transcriptional activation and repression.
ZF5 is a ubiquitously expressed protein originally identified by its ability to bind and repress the murine c-myc promoter. It contains five C-terminal zinc fingers and a conserved N-terminal ZiN/POZ domain. This motif, found in a growing number of zinc finger proteins, can inhibit DNA binding and mediate dimerization [Bardwell, V.J. and Treisman,R. (1994) Genes Dev., 8,1664-1677]. In the current study, a cyclic amplification and selection of targets (CAST) protocol detected preferred ZF5 binding sites which are highly GC-rich. Binding to these sites by ZF5 depended upon the zinc fingers and was enhanced when the ZiN/POZ domain was removed. Using transient cotransfection assays, ZF5 was shown to activate the HIV-1 LTR and repress the beta-actin promoter. The ZiN/POZ domain was shown to mediate ZF5-dependent transcriptional activation and repression. From these data, we conclude that ZF5 can both activate and repress in the context of different natural promoters and that its ZiN/POZ domain can affect two functions; DNA binding and transcriptional modulation.
Kaplan
J
J
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Calame
K
K
D016475:3T3 Cells; D000199:Actins / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D016384:Consensus Sequence; D017124:Conserved Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D051379:Mice; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism; D014162:Transfection; D016335:Zinc Fingers
D000199:Actins; D004268:DNA-Binding Proteins; D051741:Kruppel-Like Transcription Factors; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C489978:ZBTB14 protein, human; C082969:Zfp161 protein, mouse; D004247:DNA