1m9g
From Proteopedia
Solution structure of G16A-MNEI, a structural mutant of single chain monellin MNEI
Overview
The mechanism by which sweet proteins elicit a response on the T1R2-T1R3 sweet taste receptor is still mostly unknown but has been so far related to the presence of "sweet fingers" on the protein surface able to interact with the same mechanism as that of low molecular mass sweeteners. In the search for the identification of sweet fingers, we have solved the solution structure of G16A MNEI, a structural mutant that shows a reduction of one order of magnitude in sweetness with respect to its parent protein, MNEI, a single-chain monellin. Comparison of the structures of wild-type monellin and its G16A mutant shows that the mutation does not affect the structure of potential glucophores but produces a distortion of the surface owing to the partial relative displacement of elements of secondary structure. These results show conclusively that sweet proteins do not possess a sweet finger and strongly support the hypothesis that the mechanism of interaction of sweet-tasting proteins with the recently identified T1R2-T1R3 GPC receptor is different from that of low molecular mass sweeteners.
About this Structure
1M9G is a Single protein structure of sequence from Dioscoreophyllum cumminsii. Full crystallographic information is available from OCA.
Reference
The mechanism of interaction of sweet proteins with the T1R2-T1R3 receptor: evidence from the solution structure of G16A-MNEI., Spadaccini R, Trabucco F, Saviano G, Picone D, Crescenzi O, Tancredi T, Temussi PA, J Mol Biol. 2003 May 2;328(3):683-92. PMID:12706725 Page seeded by OCA on Sat May 3 00:47:24 2008
