Two new members of the emerging KDWK family of combinatorial transcription modulators bind as a heterodimer to flexibly spaced PuCGPy half-sites.
Initially recognized as a HeLa factor essential for parvovirus DNA replication, parvovirus initiation factor (PIF) is a site-specific DNA-binding complex consisting of p96 and p79 subunits. We have cloned and sequenced the human cDNAs encoding each subunit and characterized their products expressed from recombinant baculoviruses. The p96 and p79 polypeptides have 40% amino acid identity, focused particularly within a 94-residue region containing the sequence KDWK. This motif, first described for the Drosophila homeobox activator DEAF-1, identifies an emerging group of metazoan transcriptional modulators. During viral replication, PIF critically regulates the viral nickase, but in the host cell it probably modulates transcription, since each subunit is active in promoter activation assays and the complex binds to previously described regulatory elements in the tyrosine aminotransferase and transferrin receptor promoters. Within its recognition site, PIF binds coordinately to two copies of the tetranucleotide PuCGPy, which, remarkably, can be spaced from 1 to 15 nucleotides apart, a novel flexibility that we suggest may be characteristic of the KDWK family. Such tetranucleotides are common in promoter regions, particularly in activating transcription factor/cyclic AMP response element-binding protein (ATF/CREB) and E-box motifs, suggesting that PIF may modulate the transcription of many genes.
Christensen
J
J
Department of Laboratory Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Cotmore
S F
SF
Tattersall
P
P
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D020862:GC Rich Sequence; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017992:Parvovirus / Q000235:genetics; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011990:Receptors, Transferrin / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D018741:Replication Origin; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014444:Tyrosine Transaminase / Q000235:genetics
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011990:Receptors, Transferrin; D011994:Recombinant Proteins; D014157:Transcription Factors; C400299:p79 subunit, parvovirus initiation factor; C400298:p96 subunit, parvovirus initiation factor; D014444:Tyrosine Transaminase