6533b85efe1ef96bd12c04fa

RESEARCH PRODUCT

Structure-function relationships of brazzein, a sweet-tasting protein and its interactions with the human sweet taste receptor

subject

description

International audience; Brazzein is a small heat- and pH-stable sweet-tasting protein isolated from the West African plant, Pentadiplandra brazzeana. Brazzein combines a highly sweet potency, a long history of human consumption, and a remarkable stability, giving it great potential as a natural sweetener. Due to the difficulties of obtaining brazzein from its natural source, several efforts have been made to express brazzein using various heterologous expression systems. Brazzein like all classes of sweet compounds (natural sugars, natural and artificial sweeteners) are perceived through the activation of the T1R2/T1R3 heterodimeric sweet taste receptor. T1R2 and T1R3 subunits are members of the small family of class C G-protein coupled receptors (GPCRs). Class C GPCRs possess a large N-terminal domain (NTD) linked to a heptahelical transmembrane domain by a cysteine rich domain (CRD). Cellular assays, molecular docking and site-directed mutagenesis studies have revealed that the NTD of T1R2 (T1R2-NTD) contain the primary binding site for most of the sweet ligands including natural sugars and, artificial and natural sweeteners including sweet-tasting proteins. We will summarize the structure-activity relationship of brazzein and will describe the current knowledge on the putative molecular mechanism of receptor activation, which remains to be elucidated.