title: The uncoupled ATPase activity of the ABC transporter BtuC2D2 leads to a hysteretic conformational change, conformational memory, and improved activity.
abstract: ABC transporters comprise a large and ubiquitous family of proteins. From bacteria to man they translocate solutes at the expense of ATP hydrolysis. Unlike other enzymes that use ATP as an energy source, ABC transporters are notorious for having high levels of basal ATPase activity: they hydrolyze ATP also in the absence of their substrate. It is unknown what are the effects of such prolonged and constant activity on the stability and function of ABC transporters or any other enzyme. Here we report that prolonged ATP hydrolysis is beneficial to the ABC transporter BtuC2D2. Using ATPase assays, surface plasmon resonance interaction experiments, and transport assays we observe that the constantly active transporter remains stable and functional for much longer than the idle one. Remarkably, during extended activity the transporter undergoes a slow conformational change (hysteresis) and gradually attains a hyperactive state in which it is more active than it was to begin with. This phenomenon is different from stabilization of enzymes by ligand binding: the hyperactive state is only reached through ATP hydrolysis, and not ATP binding. BtuC2D2 displays a strong conformational memory for this excited state, and takes hours to return to its basal state after catalysis terminates.
authors.affiliation: Rappaport Research Institute, Department of Biochemistry, The Bruce and Ruth Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Nurit
authors.initials: N
authors.lastname: Livnat-Levanon
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: I Gilson
authors.affiliation: Department of Biochemistry and Molecular Biology, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Ben-Tal
authors.affiliation: Rappaport Research Institute, Department of Biochemistry, The Bruce and Ruth Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Oded
authors.initials: O
authors.lastname: Lewinson
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000502:physiology; D000251:Adenosine Triphosphatases / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry; D001693:Biological Transport, Active; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000502:physiology; D006868:Hydrolysis; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D018528:ATP-Binding Cassette Transporters; C050021:BtuC peptide, E coli; D029968:Escherichia coli Proteins; D008081:Liposomes; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases