Structural determinants outside of the leucine zipper influence the interactions of CREB and ATF-2: interaction of CREB with ATF-2 blocks E1a-ATF-2 complex formation.
Dimerization of leucine zipper-containing proteins has been associated characteristically with the formation of a coiled-coil structure between two compatible leucine zipper motifs. In the present study we demonstrate the association of the leucine zipper of cAMP response element-binding protein (CREB) with a zinc finger motif of ATF-2. The association of the CREB leucine zipper with the ATF-2 zinc finger is stabilized if the ATF-2 leucine zipper is intact, implying that the preferred interactive structure of ATF-2 juxtaposes the amino-terminal zinc finger motif of this protein with the carboxy-terminal leucine zipper of this same protein. Furthermore, we demonstrate that the association of the CREB leucine zipper with the ATF-2 zinc finger in vitro blocks the association of the adenoviral E1a protein with ATF-2. Similarly, overexpression of full-length CREB, or a truncated version of this protein corresponding to the carboxy-terminal 74 amino acids that make up the DNA-binding and dimerization domains, can block the ATF-2-mediated transcriptional stimulation by E1a in vivo. Mutation of the ATF-2 zinc finger motif stimulates DNA binding of this protein, and abolishes interactions with E1a and CREB proteins. These results demonstrate that the structural conformation of ATF-2 is critical for DNA binding and protein-protein interactions and, further, that leucine zippers can mediate protein-protein interactions with structural motifs other than leucine zippers.
Abdel-Hafiz
H A
HA
Department of Medicine, University of Colorado School of Medicine, Denver 80262.
Chen
C Y
CY
Marcell
T
T
Kroll
D J
DJ
Hoeffler
J P
JP
D051696:Activating Transcription Factors; D017500:Adenovirus E1A Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001798:Blood Proteins / Q000737:chemistry / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D015533:Transcriptional Activation; D015032:Zinc / Q000378:metabolism
D051696:Activating Transcription Factors; D017500:Adenovirus E1A Proteins; D001798:Blood Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D004247:DNA; D015032:Zinc