8JZ1

Crystal structure of a single-chain monellin mutant C41V

Summary for 8JZ1

• Entry DOI: 10.2210/pdb8jz1/pdb
• Descriptor: Monellin chain B,Monellin chain A (2 entities in total)
• Functional Keywords: sweet protein, plant protein
• Biological source: Dioscoreophyllum cumminsii (serendipity berry); More
• Total number of polymer chains: 2
• Total formula weight: 22447.49

Authors

Yasui, N.,Ohnuma, K.,Yamashita, A. (deposition date: 2023-07-04, release date: 2023-10-11, Last modification date: 2023-11-01)

Primary citation

Ohnuma, K.,Yamashita, A.,Yasui, N.
Investigating the Effect of Substituting a Single Cysteine Residue on the Thermal Stability of an Engineered Sweet Protein, Single-Chain Monellin.
Protein J., 42:698-708, 2023

PubMed Abstract: Single-chain monellin (SCM) is an engineered protein that links the two chains of monellin, a naturally sweet-tasting protein. This protein is an attractive candidate for use as a sugar replacement in food and beverages and has numerous other applications. Therefore, generating SCM mutants with improved stability is an active area of research to broaden the range of its potential applications. In this study, we focused on the Cys41 residue of SCM, which is a single cysteine residue present at a structurally important position. This residue is often substituted with Ser. However, this substitution may destabilize SCM because Cys41 is buried in the hydrophobic core of the protein. Therefore, we designed mutants that substituted Ala, Val, and Leu for this residue, namely C41A, C41V, and C41L. We characterized these three mutants, SCM C41S, and wild type (WT). Differential scanning fluorimetric analysis revealed that substituting Cys41 with Ala or Val increased the thermal stability of SCM, while substitution with Ser or Leu decreased its stability. Determination of the crystal structures of SCM C41A and C41V mutants revealed that the overall structures and main chain structures around the 41st residue of both mutants were almost identical to the WT. On the other hand, the orientations of the amino acid side chains near the 41st residue differed among the SCM variants. Taken together, our results indicate that substituting Cys41 with Ala or Val increases the stability of SCM and provide insight into the structural basis of this improvement.

PubMed: 37737932
DOI: 10.1007/s10930-023-10154-0

Experimental method

X-RAY DIFFRACTION (1.239 Å)