Phosphorylation of BATF regulates DNA binding: a novel mechanism for AP-1 (activator protein-1) regulation.
BATF is a member of the AP-1 (activator protein-1) family of bZIP (basic leucine zipper) transcription factors that form transcriptionally inhibitory, DNA binding heterodimers with Jun proteins. In the present study, we demonstrate that BATF is phosphorylated in vivo on multiple serine and threonine residues and at least one tyrosine residue. Reverse-polarity PAGE revealed that serine-43 and threonine-48 within the DNA binding domain of BATF are phosphorylated. To model phosphorylation of the BATF DNA binding domain, serine-43 was replaced by an aspartate residue. BATF(S43D) retains the ability to dimerize with Jun proteins in vitro and in vivo, and the BATF(S43D):Jun heterodimer localizes properly to the nucleus of cells. Interestingly, BATF(S43D) functions like wild-type BATF to reduce AP-1-mediated gene transcription, despite the observed inability of the BATF(S43D):Jun heterodimer to bind DNA. These data demonstrate that phosphorylation of serine-43 converts BATF from a DNA binding into a non-DNA binding inhibitor of AP-1 activity. Given that 40% of mammalian bZIP transcription factors contain a residue analogous to serine-43 of BATF in their DNA binding domains, the phosphorylation event described here represents a mechanism that is potentially applicable to the regulation of many bZIP proteins.
Deppmann
Christopher D
CD
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA.
Thornton
Tina M
TM
Utama
Fransiscus E
FE
Taparowsky
Elizabeth J
EJ
D000595:Amino Acid Sequence; D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D016350:Leucine Zippers; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D020836:Protein Structure, Quaternary / Q000502:physiology; D017434:Protein Structure, Tertiary; D016755:Proto-Oncogene Proteins c-jun / Q000737:chemistry; D012694:Serine / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000502:physiology*; D014157:Transcription Factors / Q000737:chemistry* / Q000502:physiology*; D014407:Tumor Cells, Cultured
D050976:Basic-Leucine Zipper Transcription Factors; C431772:Batf protein, mouse; D004268:DNA-Binding Proteins; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D012694:Serine