Analysis of an activator:coactivator complex reveals an essential role for secondary structure in transcriptional activation.
Ser-133 phosphorylation of CREB within the kinase-inducible domain (KID) promotes target gene activation via complex formation with the KIX domain of the coactivator CBP. Concurrent phosphorylation of CREB at Ser-142 inhibits transcriptional induction via an unknown mechanism. Unstructured in the free state, KID folds into a helical structure upon binding to KIX. Using site-directed mutagenesis based on the NMR structure of the KID:KIX complex, we have examined the mechanisms by which Ser-133 and Ser-142 phosphorylation regulate CREB activity. Our results indicate that phospho-Ser-133 stablizes whereas phospho-Ser-142 disrupts secondary structure-mediated interactions between CREB and CBP. Thus, differential phosphorylation of CREB may form the basis by which upstream signals regulate the specificity of target gene activation.
Joslin Diabetes Center, Research Division, Boston, Massachusetts, USA.
D
D
Parker
U S
US
Jhala
I
I
Radhakrishnan
M B
MB
Yaffe
C
C
Reyes
A I
AI
Shulman
L C
LC
Cantley
P E
PE
Wright
M
M
Montminy
D000595:Amino Acid Sequence; D047390:Casein Kinase II; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry* / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D019151:Peptide Library; D010766:Phosphorylation; D010768:Phosphoserine; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012694:Serine; D013379:Substrate Specificity; D015533:Transcriptional Activation; D014162:Transfection
D017362:Cyclic AMP Response Element-Binding Protein; D019151:Peptide Library; D011994:Recombinant Proteins; D010768:Phosphoserine; D012694:Serine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases