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.
Parker
D
D
Joslin Diabetes Center, Research Division, Boston, Massachusetts, USA.
Jhala
U S
US
Radhakrishnan
I
I
Yaffe
M B
MB
Reyes
C
C
Shulman
A I
AI
Cantley
L C
LC
Wright
P E
PE
Montminy
M
M
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