Secondary structure of the phosphocarrier protein IIIGlc, a signal-transducing protein from Escherichia coli, determined by heteronuclear three-dimensional NMR spectroscopy.
IIIGlc is a signal-transducing phosphocarrier protein of the phosphoenolpyruvate:glycose phosphotransferase system of Escherichia coli. The secondary structure of IIIGlc is determined by heteronuclear (15N, 13C) 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(10) class. The amino acids separating the active-site histidine residues (His75 and His90) form two strands (Ala76-Ser81 and Val85-Phe91) of a six-stranded antiparallel beta-sheet that brings His90 and His75 in close proximity. Sequence similarities in IIIGlc 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 Thr19-Ile22 in native IIIGlc 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 IIIGlc with the phospho-histidine-containing phosphocarrier protein of this system.
Pelton
J G
JG
Bone Research Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
Torchia
D A
DA
Meadow
N D
ND
Wong
C Y
CY
Roseman
S
S
D000595:Amino Acid Sequence; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D005947:Glucose; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000648:ultrastructure*; D011487:Protein Conformation; D015398:Signal Transduction
D029968:Escherichia coli Proteins; C032242:crr protein, E coli; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D005947:Glucose