title: The helical structure propensity in the first helix of the histidine phosphocarrier protein of Streptomyces coelicolor.
abstract: The bacterial phosphoenolpyruvate (PEP):sugar phosphotransferase system (PTS), formed by a cascade of several proteins, mediates the uptake and phosphorylation of carbohydrates, and it is also involved in signal transduction. Its uniqueness in bacteria makes the PTS a target for new antibacterial drugs. These drugs can be obtained from peptides or proteins fragments able to interfere the first step of the protein cascade: the phosphorylation of the HPr protein by the enzyme EI. We designed a peptide comprising the active site and the first alpha-helix of HPr of S. coelicolor; we also obtained a fragment of HPr by protein engineering methods, comprising the first forty-eight residues and thus, containing the amino acids of the shorter peptide. Both fragments were disordered in aqueous solution, with a similar percentage of helical structure ( approximately 7 %), and an identical free energy of helix formation. In 40 % TFE, both fragments acquired native-like helical structure, stabilized by non-native hydrophobic interactions, as shown by the 2D-NMR assignments of the shorter peptide, and the presence of similar NOE contacts in both fragments. These findings, with the kinetic results in other members of the HPr family, highlight the importance of short- and long-range interactions during the folding reaction of HPr proteins. Based on the residual helical population, hypothesis about the inhibition capacity of the PTS by both fragments are discussed.
authors.affiliation: Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain.
authors.forename: Estefanía
authors.initials: E
authors.lastname: Hurtado-Gómez
authors.forename: Marco
authors.initials: M
authors.lastname: Caprini
authors.forename: Alicia
authors.initials: A
authors.lastname: Prieto
authors.forename: José L
authors.initials: JL
authors.lastname: Neira
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D002942:Circular Dichroism; D004058:Diffusion; D008279:Magnetic Resonance Imaging; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry* / Q000235:genetics; D011138:Polytetrafluoroethylene / Q000737:chemistry / Q000494:pharmacology; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000187:drug effects; D012997:Solvents / Q000737:chemistry / Q000494:pharmacology; D048372:Streptomyces coelicolor / Q000235:genetics; D014867:Water / Q000737:chemistry / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D010446:Peptide Fragments; D012997:Solvents; D014867:Water; D011138:Polytetrafluoroethylene; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr