PMID: 23349025

Authors:

Cornilescu CC, Cornilescu G, Rao H, Porter SF, Tonelli M, Derider ML, Markley JL, Assadi-Porter FM

Title:

Temperature-dependent conformational change affecting Tyr11 and sweetness loops of brazzein.

Journal:

Proteins. 2013 Jan 24. doi: 10.1002/prot.24259.

Abstract:

The sweet protein brazzein, a member of the Csbetaalpha fold family, contains four disulfide bonds that lend a high degree of thermal and pH stability to its structure. Nevertheless, a variable temperature study has revealed that the protein undergoes a local, reversible conformational change between 37 degrees C and 3 degrees C with a midpoint about 27 degrees C that changes the orientations and side-chain hydrogen bond partners of Tyr8 and Tyr11. To test the functional significance of this effect, we used NMR saturation transfer to investigate the interaction between brazzein and the amino terminal domain (ATD) of the sweet receptor subunit T1R2; the results showed a stronger interaction at 7 degrees C than at 37 degrees C. Thus the low temperature conformation, which alters the orientations of two loops known to be critical for the sweetness of brazzein, may represent the bound state of brazzein in the complex with the human sweet receptor. Proteins 2013. (c) 2013 Wiley Periodicals, Inc.