Uncoupling conformational states from activity in an allosteric enzyme

João P Pisco, Cesira de Chiara, Kamila J Pacholarz, Acely Garza-Garcia, Roksana W Ogrodowicz, Philip A Walker, Perdita E Barran, Stephen J Smerdon, Luiz Pedro S de Carvalho

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)
137 Downloads (Pure)

Abstract

ATP-phosphoribosyltransferase (ATP-PRT) is a hexameric enzyme in conformational equilibrium between an open and seemingly active state and a closed and presumably inhibited form. The structure-function relationship of allosteric regulation in this system is still not fully understood. Here, we develop a screening strategy for modulators of ATP-PRT and identify 3-(2-thienyl)-L-alanine (TIH) as an allosteric activator of this enzyme. Kinetic analysis reveals co-occupancy of the allosteric sites by TIH and L-histidine. Crystallographic and native ion-mobility mass spectrometry data show that the TIH-bound activated form of the enzyme closely resembles the inhibited L-histidine-bound closed conformation, revealing the uncoupling between ATP-PRT open and closed conformations and its functional state. These findings suggest that dynamic processes are responsible for ATP-PRT allosteric regulation and that similar mechanisms might also be found in other enzymes bearing a ferredoxin-like allosteric domain.Active and inactive state ATP-phosphoribosyltransferases (ATP-PRTs) are believed to have different conformations. Here the authors show that in both states, ATP-PRT has a similar structural arrangement, suggesting that dynamic alterations are involved in ATP-PRT regulation by allosteric modulators.

Original languageEnglish
Article number203
Number of pages10
JournalNature Communications
Volume8
Issue number1
DOIs
Publication statusPublished - 7 Aug 2017

Keywords

  • ATP Phosphoribosyltransferase/chemistry
  • Adenosine Triphosphate/chemistry
  • Allosteric Regulation
  • Allosteric Site
  • Histidine/chemistry
  • Kinetics
  • Models, Molecular

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