Funding Organization(s): National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS); National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)
Cyclic GMP-AMP containing a unique combination of mixed phosphodiester linkages (2'3'-cGAMP) is an endogenous second messenger molecule that activates the type-I IFN pathway upon binding to the homodimer of the adaptor protein STING on the surface of ...
Cyclic GMP-AMP containing a unique combination of mixed phosphodiester linkages (2'3'-cGAMP) is an endogenous second messenger molecule that activates the type-I IFN pathway upon binding to the homodimer of the adaptor protein STING on the surface of endoplasmic reticulum membrane. However, the preferential binding of the asymmetric ligand 2'3'-cGAMP to the symmetric dimer of STING represents a physicochemical enigma. Here we show that 2'3'-cGAMP, but not its linkage isomers, adopts an organized free-ligand conformation that resembles the STING-bound conformation and pays low entropy and enthalpy costs in converting into the active conformation. Our results demonstrate that analyses of free-ligand conformations can be as important as analyses of protein conformations in understanding protein-ligand interactions.
Organizational Affiliation:
Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390;,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390;,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390; Chuo.Chen@utsouthwestern.edu.,Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390.
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