Optimizing the Photocontrol of bZIP Coiled Coils with Azobenzene Crosslinkers: Role of the Crosslinking Site

• Published in: Chembiochem : a European journal of chemical biology 2015-08, Vol.16 (12), p.1757-1763
• Main Authors: Ali, Ahmed M., Forbes, Matthew W., Woolley, G. Andrew
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Azo Compounds - chemistry; azobenzene; Base Sequence; Basic-Leucine Zipper Transcription Factors - chemistry; Basic-Leucine Zipper Transcription Factors - metabolism; Circular Dichroism; coiled coils; CREB; CREB-Binding Protein - chemistry; CREB-Binding Protein - genetics; Cross-Linking Reagents - chemistry; helical propensity; Light; Molecular Sequence Data; photocontrol; Signal transduction; Spectrometry, Mass, Electrospray Ionization
• ISSN: 1439-4227; 1439-7633
• DOI: 10.1002/cbic.201500191

DNA binding by bZIP‐type coiled‐coil proteins can be inhibited by dominant negative versions of the proteins in which the N‐terminal basic region is replaced by an acidic extension. Photocontrol of bZIP function can be achieved by introducing intramolecular azobenzene‐based crosslinkers into dominant negatives. We show that the largest degree of photocontrol is achieved when the crosslinker is introduced into the zipper region of the dominant negative between Cys residues placed at f sites in the heptad segment showing the highest intrinsic helical propensity. The overall affinity of the dominant negative can then be tuned by varying the length of the acidic extension. Systematic testing of potential sites for cis/trans photoswitchable azobenzene‐based crosslinkers leads to effective light‐controlled inhibitors of CREB transcription factors. The largest degree of photocontrol is achieved when the crosslinker is in the zipper region between Cys residues in the heptad segment showing the highest intrinsic helical propensity.