A Loose Domain Swapping Organization Confers a Remarkable Stability to the Dimeric Structure of the Arginine Binding Protein from Thermotoga maritima

摘要: The arginine binding protein from Thermatoga maritima (TmArgBP), a substrate (SBP) involved in the ABC system of solute transport, presents number remarkable properties. These include an extraordinary stability to temperature and chemical denaturants tendency form multimeric structures, uncommon feature among SBPs transport. Here we report biophysical structural characterization TmArgBP dimer. Our data indicate that dimer is endowed with since its full dissociation requires high as well SDS urea at concentrations. In order elucidate atomic level properties this intriguing protein, determined crystallographic structures apo arginine-bound forms using MAD SAD methods, respectively. comparison liganded unliganded models demonstrates tertiary structure undergoes very large re-organization upon binding. This transition follows Venus Fly-trap mechanism, although entity observed larger than homologous proteins. Intriguingly, dimerizes through swapping C-terminal helix. stabilized exclusively by interactions established Therefore, combines conformational freedom. represents example variations amplified quaternary domain swapping. Although biological relevance needs further assessments, molecular modelling suggests two subunits may simultaneously interact distinct transporters. Moreover, present provide some clues about determinants biomolecule. availability accurate 3D model powerful tool for design new suited biotechnological applications.