3PYJ

Reduced sweetness of a monellin (MNEI) mutant results from increased protein flexibility and disruption of a distant poly-(L-proline) II helix

3PYJ の概要

• エントリーDOI: 10.2210/pdb3pyj/pdb
• 関連するPDBエントリー: 2O9U 3PXM
• 分子名称: Monellin chain B/Monellin chain A chimeric protein, FORMIC ACID (3 entities in total)
• 機能のキーワード: poly-(l-proline) ii helix, sweet protein, plant protein
• 由来する生物種: Dioscoreophyllum cumminsii (Serendipity berry); 詳細
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 11479.10

構造登録者

Hobbs, J.R.,Conn, G.C.,Munger, S.D.,Templeton, C.M. (登録日: 2010-12-13, 公開日: 2011-04-06, 最終更新日: 2024-02-21)

主引用文献

Templeton, C.M.,Ostovar Pour, S.,Hobbs, J.R.,Blanch, E.W.,Munger, S.D.,Conn, G.L.
Reduced Sweetness of a Monellin (MNEI) Mutant Results from Increased Protein Flexibility and Disruption of a Distant Poly-(L-Proline) II Helix.
Chem Senses, 36:425-434, 2011

PubMed Abstract: Monellin is a highly potent sweet-tasting protein but relatively little is known about how it interacts with the sweet taste receptor. We determined X-ray crystal structures of 3 single-chain monellin (MNEI) proteins with alterations at 2 core residues (G16A, V37A, and G16A/V37A) that induce 2- to 10-fold reductions in sweetness relative to the wild-type protein. Surprisingly, no changes were observed in the global protein fold or the positions of surface amino acids important for MNEI sweetness that could explain these differences in protein activity. Differential scanning calorimetry showed that while the thermal stability of each mutant MNEI was reduced, the least sweet mutant, G16A-MNEI, was not the least stable protein. In contrast, solution spectroscopic measurements revealed that changes in protein flexibility and the C-terminal structure correlate directly with protein activity. G16A mutation-induced disorder in the protein core is propagated via changes to hydrophobic interactions that disrupt the formation and/or position of a critical C-terminal poly-(L-proline) II helix. These findings suggest that MNEI interaction with the sweet taste receptor is highly sensitive to the relative positions of key residues across its protein surface and that loss of sweetness in G16A-MNEI may result from an increased entropic cost of binding.

PubMed: 21343241
DOI: 10.1093/chemse/bjr007

実験手法

X-RAY DIFFRACTION (2 Å)