2KYQ: 1H, 15N, 13C chemical shifts and structure of CKR-brazzein

Brazzein, a 54 residue sweet-tasting protein, is thought to participate in a multipoint binding interaction with the sweet taste receptor. Proposed sites for interaction with the receptor include 2 surface loops and the disulfide bond that connects the N- and C-termini. However, the importance of each site is not well understood. To characterize the structural role of the termini in the sweetness of brazzein, the position of the disulfide bond connecting the N- and C-termini was shifted by substituting K3-C4-K5 with C3-K4-R5. The apparent affinity and V(max) of the C3-K4-R5-brazzein (CKR-brazzein) variant were only modestly decreased compared with the wild-type (WT) brazzein. We determined a high-resolution structure of CKR-brazzein by nuclear magnetic resonance spectroscopy (backbone root mean square deviation of 0.39 A). Comparing the structure of CKR-brazzein with that of WT-brazzein revealed that the terminal beta-strands of the variant display extended beta-structure and increased dynamics relative to WT-brazzein. These results support previous mutagenesis studies and further suggest that, whereas interactions involving the termini are necessary for full function of brazzein, the termini do not constitute the primary site of interaction between brazzein and the sweet taste receptor.
PDB ID: 2KYQDownload
MMDB ID: 90543
PDB Deposition Date: 2010/6/7
Updated in MMDB: 2011/12
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Biological Unit for 2KYQ: monomeric; determined by author
Molecular Components in 2KYQ
Label Count Molecule
Protein (1 molecule)
Defensin-like Protein
Molecule annotation
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