tailieunhanh - Báo cáo khoa học: Energetic coupling along an allosteric communication channel drives the binding of Jun-Fos heterodimeric transcription factor to DNA

Although allostery plays a central role in driving protein–DNA interac-tions, the physical basis of such cooperative behavior remains poorly understood. In the present study, using isothermal titration calorimetry in conjunction with site-directed mutagenesis, we provide evidence that an intricate network of energetically-coupled residues within the basic regions of the Jun-Fos heterodimeric transcription factor accounts for its allosteric binding to DNA. | ijFEBS Journal Energetic coupling along an allosteric communication channel drives the binding of Jun-Fos heterodimeric transcription factor to DNA Kenneth L. Seldeen Brian J. Deegan Vikas Bhat David C. Mikles Caleb B. McDonald and Amjad Farooq Department of Biochemistry Molecular Biology and USylvester Braman Family Breast Cancer Institute Leonard Miller Schoolof Medicine University of Miami FL USA Keywords allosteric communication AP1-DNA thermodynamics cooperative binding energetic coupling isothermal titration calorimetry Correspondence A. Farooq Department of Biochemistry Molecular Biology and USylvester Braman Family Breast Cancer Institute Leonard Miller Schoolof Medicine University of Miami Miami FL 33136 USA Fax 1 305 243 3955 Tel 1 305 243 2429 E-mail amjad@ Received 7 February 2011 revised 4 April 2011 accepted 11 April 2011 doi Although allostery plays a central role in driving protein-DNA interactions the physical basis of such cooperative behavior remains poorly understood. In the present study using isothermal titration calorimetry in conjunction with site-directed mutagenesis we provide evidence that an intricate network of energetically-coupled residues within the basic regions of the Jun-Fos heterodimeric transcription factor accounts for its allosteric binding to DNA. Remarkably energetic coupling is prevalent in residues that are both close in space as well as residues distant in space implicating the role of both short- and long-range cooperative interactions in driving the assembly of this key protein-DNA interaction. Unexpectedly many of the energetically-coupled residues involved in orchestrating such a cooperative network of interactions are poorly conserved across other members of the basic zipper family emphasizing the importance of basic residues in dictating the specificity of basic zipper-DNA interactions. Collectively our thermodynamic analysis maps an allosteric communication channel .