Domain swapping dissection in Thermotoga maritima arginine binding protein: How structural flexibility may compensate destabilization

摘要: Thermotoga maritima Arginine Binding Protein (TmArgBP) is a valuable candidate for arginine biosensing in diagnostics. This protein endowed with unusual structural properties that include an extraordinary thermal/chemical stability, domain swapped structure undergoes large tertiary and quaternary transition, the ability to form non-canonical oligomeric species. As intrinsic stability of TmArgBP allows extensive manipulations, we here dissected its two parts: main body deprived swapping fragment (TmArgBP20-233) C-terminal peptide corresponding helical element. Both elements have been characterized independently or combination using repertoire biophysical/structural techniques. Present investigations clearly indicate TmArgBP20-233 represents better scaffold sensing compared wild-type protein. Moreover, our data demonstrate ligand-free ligand-bound forms respond very differently this helix deletion. drastic perturbation has important impact on whereas it barely affects state. The crystallographic structures these provide rationale puzzling observation. Indeed, arginine-bound state rigid virtually unchanged upon truncation. On other hand, flexible able adopt novel as consequence Therefore, flexibility endows remarkable robustness severe perturbations. In scenario, dissection highlights intriguing connection between destabilizing/stabilizing effects overall could operate also proteins.