Secondary structure of the phosphocarrier protein III sup Glc , a signal-transducing protein from Escherichia coli, determined by heteronuclear three-dimensional NMR spectroscopy

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 88:8
• Main Authors: Pelton, J.G., Torchia, D.A., Meadow, N.D., Cing-Yuen Wong, Roseman, S.
• Format: Journal Article
• Language: English
• Published: United States 15.04.1991
• Subjects: 550201 - Biochemistry- Tracer Techniques; BACTERIA; BASIC BIOLOGICAL SCIENCES; CARBON 13; CARBON ISOTOPES; ENZYMES; ESCHERICHIA COLI; EVEN-ODD NUCLEI; ISOTOPES; LIGHT NUCLEI; MAGNETIC RESONANCE; MEMBRANE PROTEINS; MEMBRANE TRANSPORT; MICROORGANISMS; NITROGEN 15; NITROGEN ISOTOPES; NMR SPECTRA; NUCLEAR MAGNETIC RESONANCE; NUCLEI; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; OVERHAUSER EFFECT; PHOSPHOENOLPYRUVATE; PHOSPHORUS-GROUP TRANSFERASES; PHOSPHOTRANSFERASES; PROTEINS; RESONANCE; SPECTRA; STABLE ISOTOPES; TRANSFERASES
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.88.8.3479

III{sup Glc} is signal-transducing phosphocarrier protein of the phosphoenolpyruvate:glycose phosphotransferase system of Escherichia coli. The secondary structure of III{sup Glc} is determined by heteronuclear ({sup 15}N, {sup 13}C) three-dimensional NMR spectroscopy. Sequential, medium-range, and long-range nuclear Overhauser effects seen in NMR spectra are used to elucidate 11 antiparallel {beta}-strands and four helical segments. The medium-range nuclear Overhauser effect patterns suggest that the helices are either distorted {alpha}-helices or are of the 3{sub 10} class. The amino acids separating the active-site histidine residues (His{sup 75} and His{sup 90}) form two strands (Ala{sup 76}-Ser{sup 81} and Val{sup 85}-Phe{sup 91}) of a six-stranded antiparallel {beta}-sheet that brings His{sup 90} and His{sup 75} in close proximity. Sequence similarities in III{sup Glc} and several other sugar-transport proteins suggest that the histidine residues within these proteins may be arranged in a similar manner. The 18-residue N-terminal peptide that precedes {beta}-strand Thr{sup 19}-Ile{sup 22} in native III{sup Glc} is disordered and does not interact with the rest of the protein. Furthermore, removal of the N-terminal heptapeptide by a specific endopeptidase does not affect the structure of the remaining protein, thus explaining the phospho-acceptor activity of modified III{sup Glc} with the phospho-histidine-containing phosphocarrier protein of this system.