Phosphorylation of serine-46 in HPr, a key regulatory protein in bacteria, results in stabilization of its solution structure.
The serine-phosphorylated form of histidine-containing protein (HPr), a component of the phosphoenolpyruvate:sugar phosphotransferase system from Bacillus subtilis, has been characterized by NMR spectroscopy and solvent denaturation studies. The results indicate that phosphorylation of Ser 46, the N-cap of alpha-helix-B, does not cause a conformational change but rather stabilizes the helix. Amide proton exchange rates in helix-B are decreased and phosphorylation stabilizes the protein to solvent and thermal denaturation, with a delta delta G of 0.7-0.8 kcal mol-1. A mutant in which Ser 46 is replaced by aspartic acid shows a similar stabilization, indicating that an electrostatic interaction between the negatively charged groups and the helix macrodipole contributes significantly to the stabilization.
Pullen
K
K
Department of Biochemistry, University of Washington, Seattle 98195-7742, USA.
Rajagopal
P
P
Branchini
B R
BR
Huffine
M E
ME
Reizer
J
J
Saier
M H
MH
Scholtz
J M
JM
Klevit
R E
RE
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D004355:Drug Stability; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D010766:Phosphorylation; D010768:Phosphoserine / Q000737:chemistry / Q000378:metabolism*; D017433:Protein Structure, Secondary; D013816:Thermodynamics
D001426:Bacterial Proteins; D010768:Phosphoserine; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr