Stability and binding of the phosphorylated species of the N-terminal domain of enzyme I and the histidine phosphocarrier protein from the Streptomyces coelicolor phosphoenolpyruvate:sugar phosphotransferase system.

Rosa Doménech, Ana Isabel Martínez-Gómez, David Aguado-Llera, Sergio Martínez-Rodríguez, Josefa María Clemente-Jiménez, Adrián Velázquez-Campoy, José L Neira

Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain.

Archives of biochemistry and biophysics 2012 Oct 1

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The phosphotransferase system (PTS) is involved in the use of carbon sources in bacteria. It is formed by two general proteins: enzyme I (EI) and the histidine phosphocarrier (HPr), and various sugar-specific permeases. EI is formed by two domains, with the N-terminal domain (EIN) being responsible for the binding to HPr. In low-G+C Gram-positive bacteria, HPr becomes phosphorylated not only by phosphoenolpyruvate (PEP) at the active-site histidine, but also by ATP at a serine. In this work, we have characterized: (i) the stability and binding affinities between the active-site-histidine phosphorylated species of HPr and the EIN from Streptomyces coelicolor; and (ii) the stability and binding affinities of the species involving the phosphorylation at the regulatory serine of HPr(sc). Our results show that the phosphorylated active-site species of both proteins are less stable than the unphosphorylated counterparts. Conversely, the Hpr-S47D, which mimics phosphorylation at the regulatory serine, is more stable than wild-type HPr(sc) due to helical N-capping effects, as suggested by the modeled structure of the protein. Binding among the phosphorylated and unphosphorylated species is always entropically driven, but the affinity and the enthalpy vary widely. Copyright © 2012 Elsevier Inc. All rights reserved.

Citation

Rosa Doménech, Ana Isabel Martínez-Gómez, David Aguado-Llera, Sergio Martínez-Rodríguez, Josefa María Clemente-Jiménez, Adrián Velázquez-Campoy, José L Neira. Stability and binding of the phosphorylated species of the N-terminal domain of enzyme I and the histidine phosphocarrier protein from the Streptomyces coelicolor phosphoenolpyruvate:sugar phosphotransferase system. Archives of biochemistry and biophysics. 2012 Oct 1;526(1):44-53