Mechanism of CREB recognition and coactivation by the CREB-regulated transcriptional coactivator CRTC2

Abstract

Basic leucine zipper (bZip) transcription factors regulate cellular gene expression in response to a variety of extracellular signals and nutrient cues. Although the bZip domain is widely known to play significant roles in DNA binding and dimerization, recent studies point to an additional role for this motif in the recruitment of the transcriptional apparatus. For example, the cAMP response element binding protein (CREB)-regulated transcriptional coactivator (CRTC) family of transcriptional coactivators has been proposed to promote the expression of calcium and cAMP responsive genes, by binding to the CREB bZip in response to extracellular signals. Here we show that the CREB-binding domain (CBD) of CRTC2 folds into a single isolated 28-residue helix that seems to be critical for its interaction with the CREB bZip. The interaction is of micromolar affinity on palindromic and variant half-site cAMP response elements (CREs). The CBD and CREB assemble on the CRE with 2:2:1 stoichiometry, consistent with the presence of one CRTC binding site on each CREB monomer. Indeed, the CBD helix and the solvent-exposed residues in the dimeric CREB bZip coiled-coil form an extended protein-protein interface. Because mutation of relevant bZip residues in this interface disrupts the CRTC interaction without affecting DNA binding, our results illustrate that distinct DNA binding and transactivation functions are encoded within the structural constraints of a canonical bZip domain.transcription regulation | cellular signaling | protein-protein interaction

Amino Acid Residues of RegA Important for Interactions with the CbbR-DNA Complex of Rhodobacter sphaeroides

“…In Vibrio cholerae, the wing region of the HTH of ToxR interacts with a second transcriptional regulator, TcpP, to activate gene expression (28), and in the marine bacterium Erythrobacter litoralis, interaction between the HTH domain and the light-oxygen-voltage domain of the blue-lightactivated photosensory protein (EL222) inhibits DNA binding (29). Other examples of DBD interactions have also been reported (26,27,30,31).…”

“…There are several examples of DBDs interacting with other proteins (or domains), illustrating an important secondary function for DBDs, in addition to binding DNA (26)(27)(28)(29)(30)(31)(32). It is therefore no surprise that DBDs have evolved the ability to bind other proteins or other DBDs to gain additional functions, since many promoters contain DNA binding sites that are within a few base pairs of each other or even overlap.…”

Structural insights into the assembly of the histone deacetylase-associated Sin3L/Rpd3L corepressor complex

“…SEC-MALS experiments were performed and analyzed exactly as described previously (51). Proteins or protein mixtures of 37-100 μM in 20 mM Tris buffer (pH 7.4) containing 200 mM NaCl and 2 mM DTT or 50 mM Tris buffer (pH 8.0), 200 mM NaCl, and 2 mM tris(2-carboxyethyl)phosphine were used.…”

CRTC1/MAML2 gain-of-function interactions with MYC create a gene signature predictive of cancers with CREB–MYC involvement

“…4B). Importantly, K33 is immediately adjacent to two residues conserved across all three CRTC family members that were recently shown to be important for interactions with the CREB bZip domain (45). The disabling effects of the K33P mutant on the native EVX1 promoter were confirmed using a completely defined 5×GAL4::UAS promoter, which revealed that the C1/M2 K33P mutant could not activate either CREB or its paralog ATF1 (Fig.…”