The TFE-induced transient native-like structure of the intrinsically disordered domain of Escherichia coli RNA polymerase

摘要

The transient folding of domain 4 of an E. coli RNA polymerase subunit () induced by an increasing concentration of 2,2,2-trifluoroethanol (TFE) in an aqueous solution was monitored by means of CD and heteronuclear NMR spectroscopy. NMR data, collected at a 30 % TFE, allowed the estimation of the population of a locally folded structure (CSI descriptors) and of local backbone dynamics (N-15 relaxation). The spontaneous organization of the helical regions of the initially unfolded protein into a TFE-induced 3D structure was revealed from structural constraints deduced from N-15- to C-13-edited NOESY spectra. In accordance with all the applied criteria, three highly populated alpha-helical regions, separated by much more flexible fragments, form a transient HLHTH motif resembling those found in PDB structures resolved for homologous proteins. All the data taken together demonstrate that TFE induces a transient native-like structure in the intrinsically disordered protein.