5LC7

Crystal structure of a single chain monellin mutant: E23Q/Q28K/C41S/Y65R-MNEI

Summary for 5LC7

• Entry DOI: 10.2210/pdb5lc7/pdb
• Descriptor: Monellin chain B,Monellin chain A (2 entities in total)
• Functional Keywords: plant protein, sweet protein
• Biological source: Dioscoreophyllum cumminsii (Serendipity berry); More
• Total number of polymer chains: 2
• Total formula weight: 22794.14

Authors

Pica, A.,Merlino, A. (deposition date: 2016-06-19, release date: 2016-10-05, Last modification date: 2024-01-10)

Primary citation

Leone, S.,Pica, A.,Merlino, A.,Sannino, F.,Temussi, P.A.,Picone, D.
Sweeter and stronger: enhancing sweetness and stability of the single chain monellin MNEI through molecular design.
Sci Rep, 6:34045-34045, 2016

PubMed Abstract: Sweet proteins are a family of proteins with no structure or sequence homology, able to elicit a sweet sensation in humans through their interaction with the dimeric T1R2-T1R3 sweet receptor. In particular, monellin and its single chain derivative (MNEI) are among the sweetest proteins known to men. Starting from a careful analysis of the surface electrostatic potentials, we have designed new mutants of MNEI with enhanced sweetness. Then, we have included in the most promising variant the stabilising mutation E23Q, obtaining a construct with enhanced performances, which combines extreme sweetness to high, pH-independent, thermal stability. The resulting mutant, with a sweetness threshold of only 0.28 mg/L (25 nM) is the strongest sweetener known to date. All the new proteins have been produced and purified and the structures of the most powerful mutants have been solved by X-ray crystallography. Docking studies have then confirmed the rationale of their interaction with the human sweet receptor, hinting at a previously unpredicted role of plasticity in said interaction.

PubMed: 27658853
DOI: 10.1038/srep34045

Experimental method

X-RAY DIFFRACTION (1.55 Å)