Uncoupling conformational states from activity in an allosteric enzyme

• Published in: Nature communications 2017-08, Vol.8 (1), p.203-10, Article 203
• Main Authors: Pisco, João P., de Chiara, Cesira, Pacholarz, Kamila J., Garza-Garcia, Acely, Ogrodowicz, Roksana W., Walker, Philip A., Barran, Perdita E., Smerdon, Stephen J., de Carvalho, Luiz Pedro S.
• Format: Article
• Language: English
• Subjects: 631/45/607/1172; 631/535/1266; 631/92/507; 631/92/607; Adenosine Triphosphate - chemistry; Adenosine Triphosphate - metabolism; Alanine; Allosteric properties; Allosteric Regulation; Allosteric Site; ATP; ATP Phosphoribosyltransferase - chemistry; ATP Phosphoribosyltransferase - genetics; ATP Phosphoribosyltransferase - metabolism; Binding sites; Conformation; Crystallography; Enzymes; Ferredoxin; Histidine; Histidine - chemistry; Histidine - metabolism; Humanities and Social Sciences; Ionic mobility; Kinetics; Mass spectrometry; Mass spectroscopy; Models, Molecular; Modulators; multidisciplinary; Phosphoribosyltransferase; Science; Science (multidisciplinary); Structure-function relationships
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-017-00224-0

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.