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Phosphorylation of serine‐46 in HPr, a key regulatory protein in bacteria, results in stabilization of its solution structure
Author(s) -
Pullen Katherine,
Rajagopal Ponni,
Klevit Rachel E.,
Branchini Bruce R.,
Reizer Jonathan,
Saier Milton H.,
Scholtz J. Martin,
Huffine Mary Elizabeth
Publication year - 1995
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560041204
Subject(s) - pep group translocation , phosphorylation , bacillus subtilis , chemistry , histidine , helix (gastropod) , denaturation (fissile materials) , serine , phosphoenolpyruvate carboxykinase , threonine , biophysics , biochemistry , stereochemistry , crystallography , bacteria , amino acid , biology , enzyme , ecology , snail , nuclear chemistry , genetics
The serine‐phosphorylated form of histidine‐containing protein (HPr), a component of the phosphoenol‐pyruvate: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 α ‐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 ΔΔ 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.