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.
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.
Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain.
Rosa
R
Doménech
Ana Isabel
AI
Martínez-Gómez
David
D
Aguado-Llera
Sergio
S
Martínez-Rodríguez
Josefa María
JM
Clemente-Jiménez
Adrián
A
Velázquez-Campoy
José L
JL
Neira
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D004795:Enzyme Stability; D006860:Hydrogen Bonding; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D012694:Serine / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000201:enzymology*; D013816:Thermodynamics
D001426:Bacterial Proteins; D010750:Phosphoproteins; D012694:Serine; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr