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Protein Sci. 1995 Dec;4(12):2478-86.

Phosphorylation of serine-46 in HPr, a key regulatory protein in bacteria, results in stabilization of its solution structure.

Author information

1
Department of Biochemistry, University of Washington, Seattle 98195-7742, USA.

Abstract

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.

PMID:
8580838
PMCID:
PMC2143046
DOI:
10.1002/pro.5560041204
[Indexed for MEDLINE]
Free PMC Article

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