Cyclic-AMP-responsive transcriptional activation of CREB-327 involves interdependent phosphorylated subdomains.
Cyclic AMP-regulated gene expression is mediated by specific phosphoproteins (CREBs) which bind to cAMP-responsive elements of gene promoters. By analyzing the transactivation activities and phosphorylations in vivo of deletion and point mutated chimeric fusion proteins of the placental CREB-327, in which the DNA-binding domain is replaced by the heterologous binding-domain of the yeast transcription factor GAL4, we localized the cAMP-responsive and phosphorylated domain to a minimal-essential sequence module of 46 amino acids (residues 92-137). This serine-rich, multiply-phosphorylated sequence consists of at least three interdependent subdomains required for transcriptional activation. Although phosphorylation of serine-119 by cyclic AMP-dependent protein kinase A is necessary for transcriptional activation, such activation requires both a phosphorylated heptadecapeptide domain located ten residues amino terminal to the serine-119 and an eleven-residue domain carboxyl terminal to the serine-119. Deletion of these two domains does not impair phosphorylation of serine-119. Further, deletion of the carboxyl-terminal domain does not alter phosphorylation of the heptadecapeptide domain. We propose that akin to the phosphorylation-dependent activation of enzymes, the transcriptional transactivation functions of CREB-327 involve a phosphorylation-dependent allosteric conformational mechanism.
Lee
C Q
CQ
Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Boston.
Yun
Y D
YD
Hoeffler
J P
JP
Habener
J F
JF
D000595:Amino Acid Sequence; D001665:Binding Sites; D000242:Cyclic AMP / Q000494:pharmacology*; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000187:drug effects*; D014407:Tumor Cells, Cultured
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D012694:Serine; D000242:Cyclic AMP; D011494:Protein Kinases