Importance of Glu53 in the C-terminal region of brazzein, a sweet-tasting protein

BACKGROUND The sweetness of brazzein, one of the known sweet proteins, is dependent on charges and/or structures of its specific amino acid side chains. As the residues in the C‐terminus of brazzein are known to play a critical role in sweetness, the currently unknown function of Glu53 requires furt...

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Published in:Journal of the science of food and agriculture 2016-07, Vol.96 (9), p.3202-3206
Main Authors: Lim, Jin-Kyung, Jang, Jin-Chul, Kong, Ji-Na, Kim, Myung-Chul, Kong, Kwang-Hoon
Format: Article
Language:English
Subjects:
Amino Acid Motifs
Amino Acid Substitution - genetics
Amino acids
Arginine - chemistry
brazzein
Construction
Escherichia coli - genetics
Food science
Foods
Gene Expression Regulation
Glu53
Glutamine - chemistry
Models, Molecular
mutagenesis
Mutagenesis, Site-Directed
Mutations
Plant Proteins - chemistry
Plant Proteins - genetics
Protein Conformation
Proteins
Receptors
Residues
Sensory perception
Sequence Analysis, Protein
Structure-Activity Relationship
Sweetening Agents - chemistry
sweetness determinant
Sweets
Taste
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Summary:BACKGROUND The sweetness of brazzein, one of the known sweet proteins, is dependent on charges and/or structures of its specific amino acid side chains. As the residues in the C‐terminus of brazzein are known to play a critical role in sweetness, the currently unknown function of Glu53 requires further study. RESULTS To identify important residues responsible for the sweetness of the protein brazzein, four mutants of the Glu53 residue in the C‐terminal region of des‐pE1M‐brazzein, which lacks the N‐terminal pyroglutamate, were constructed using site‐directed mutagenesis. Mutations of Glu53 substitution to Ala or Asp significantly decreased the sweetness. On the other hand, a Lys mutation resulted in a molecule with sweetness similar to that of des‐pE1M‐brazzein. Mutation of Glu53 to Arg resulted in a molecule significantly sweeter than des‐pE1M‐brazzein, which agrees with previous findings showing that mutation with positively charged residues results in a sweeter protein. CONCLUSION Our results suggest that the residue at position 53 is crucial for the sweetness of brazzein, which may be interacting with the sweet‐taste receptor. © 2015 Society of Chemical Industry
ISSN:0022-5142
1097-0010
DOI:10.1002/jsfa.7501