Epitope mapping by mutagenesis distinguishes between the two tertiary structures of the histidine-containing protein HPr.
Thirty-four of the 85 residues of the histidine-containing protein HPr of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system have been changed by site-directed mutagenesis. Many of the mutations have wild-type activity suggesting an unaltered tertiary structure but have altered binding to three monoclonal antibodies: Jel42, Jel44, and Jel323. This altered binding defines the residues that are involved in the epitopes of HPr. At present, two different three-dimensional structures have been determined for HPr, one from two-dimensional nuclear magnetic resonance spectra and the other from x-ray diffraction of HPr crystals. The epitope mapping for Jel42 does not distinguish between the tertiary structures. However, only the HPr structure derived from two-dimensional nuclear magnetic resonance spectra is consistent with a contiguous surface binding site that can be defined as the epitope for Jel44. Thus the x-ray structure may represent a partially unfolded HPr.
Sharma
S
S
Department of Biochemistry, University of Saskatchewan, Saskatoon, Canada.
Georges
F
F
Delbaere
L T
LT
Lee
J S
JS
Klevit
R E
RE
Waygood
E B
EB
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins / Q000235:genetics; D001666:Binding Sites, Antibody; D000939:Epitopes / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D006639:Histidine; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics* / Q000276:immunology; D011487:Protein Conformation
D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D000939:Epitopes; D006639:Histidine; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr