5X9L

Recombinant thaumatin I at 0.9 Angstrom

Summary for 5X9L

• Entry DOI: 10.2210/pdb5x9l/pdb
• Descriptor: Thaumatin I, L(+)-TARTARIC ACID, GLYCEROL, ... (4 entities in total)
• Functional Keywords: sweet-tasting protein, sweet receptor, plant protein
• Biological source: Thaumatococcus daniellii (Katemfe)
• Total number of polymer chains: 1
• Total formula weight: 22804.50

Authors

Masuda, T.,Okubo, K.,Sugahara, M.,Suzuki, M.,Mikami, B. (deposition date: 2017-03-08, release date: 2018-03-14, Last modification date: 2024-11-06)

Primary citation

Masuda, T.,Okubo, K.,Murata, K.,Mikami, B.,Sugahara, M.,Suzuki, M.,Temussi, P.A.,Tani, F.
Subatomic structure of hyper-sweet thaumatin D21N mutant reveals the importance of flexible conformations for enhanced sweetness.
Biochimie, 157:57-63, 2019

PubMed Abstract: One of the sweetest proteins found in tropical fruits (with a threshold of 50 nM), thaumatin, is also used commercially as a sweetener. Our previous study successfully produced the sweetest thaumatin mutant (D21N), designated hyper-sweet thaumatin, which decreases the sweetness threshold to 31 nM. To investigate why the D21N mutant is sweeter than wild-type thaumatin, we compared the structure of the D21N mutant solved at a subatomic resolution of 0.93 Å with that of wild-type thaumatin determined at 0.90 Å. Although the overall structure of the D21N mutant resembles that of wild-type thaumatin, our subatomic resolution analysis successfully assigned and discriminated the detailed atomic positions of side-chains at position 21. The relative B-factor value of the side-chain at position 21 in the D21N mutant was higher than that of wild-type thaumatin, hinting at a greater flexibility of side-chain at 21 in the hyper-sweet D21N mutant. Furthermore, alternative conformations of Lys19, which is hydrogen-bonded to Asp21 in wild-type, were found only in the D21N mutant. Subatomic resolution analysis revealed that flexible conformations at the sites adjacent to positions 19 and 21 play a crucial role in enhancing sweet potency and may serve to enhance the complementarity of electrostatic potentials for interaction with the sweet taste receptor.

PubMed: 30389513
DOI: 10.1016/j.biochi.2018.10.020

Experimental method

X-RAY DIFFRACTION (0.9 Å)