Open AccessThree-dimensional structure of the Escherichia coli phosphocarrier protein IIIglc.
Author(s) -
David K. Worthylake,
N D Meadow,
Saul Roseman,
DerIng Liao,
Osnat Herzberg,
S.J. Remington
Publication year - 1991
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.88.23.10382
Subject(s) - chemistry , crystallography , crystal structure , antiparallel (mathematics) , protein structure , side chain , stereochemistry , pep group translocation , molecule , escherichia coli , physics , biochemistry , organic chemistry , quantum mechanics , magnetic field , gene , polymer
The crystal structure of a proteolytically modified form of the Escherichia coli phosphocarrier and signal transducing protein IIIglc has been determined by multiple isomorphous and molecular replacement. The model has been refined to an R-factor of 0.166 for data between 6- and 2.1-A resolution with an rms deviation of 0.020 A from ideal bond lengths and 3.2 degrees from ideal bond angles. The molecule is a beta-sheet sandwich, with six antiparallel strands on either side. Several short distorted helices line the periphery of the active site, which is a shallow extremely hydrophobic depression approximately 18 A in diameter near the center of one face. The side chains of the active site histidine residues 75 and 90 face each other at the center of the depression, with the N3 positions exposed to solvent, separated by 3.3 A in an excellent position to form adducts with phosphate. Chloroplatinate forms a divalent adduct with both histidyl side chains, suggesting that the phosphodonor reaction might proceed through a similar transition state. The hydrophobic patch forms the primary crystal contact, suggesting a mode of association of IIIglc with other components of the phosphoenolpyruvate-dependent phosphotransferase system.