Part:BBa_K4227002

Monellin

Usage and Biology

Natural monellin is a sweet protein obtained from the West African forest plant Dioscoreophyllum cumminsii Diels. It is 3,000 times sweeter than sucrose on a weight basis and can be used in industry as a sweetener and a flavor enhancer. It has some important advantages over artificial sweeteners. It is low in calories, safe, and neither introduces nonnatural metabolites into the body nor perturbs the balance of the amino acid pool as decomposition of the protein results in a natural distribution of all amino acids.^[1]

The Bacillus subtilis was engineered by us to use as the oral probiotics. So, we design this part monellin to be a report module in the users' mouths. When the monellin was expressed, the user will taste the sweetness.

Characterization

(The following experimental data are from the literature and modeling, not the actual data made by the experiment)

Since our experiment is severely influenced by COVID-19 in experimenter, materials, equipment and so on this year. We have to collect these data by the literature and modeling

We knew from the literature that natural monellin consists of two polypeptides containing 45 amino acid residues and 50 amino acid residues. Weak noncovalent bonds hold the two chains together. It is easily dissociated by heat or pH changes.

So in order to use the monellin as a report molecule, we choose a kind of single strain monellin in which the two polypeptides are connected by a glycine residue, was designed and was found to be more stable under extreme heat and pH conditions without changing its sweetness. ^[2]

Fig 1. The improvement of the stable under extreme heat and pH conditions.^[2]

Modeling

Our modeling was based on the law of mass action.

Fig 2. The expression level of the monellin.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Reference

[1] Zhongjun Chen, Cai Heng, Zhengying Li, Xinle Liang, Shangguan Xinchen. Expression and secretion of a single-chain sweet protein monellin in Bacillus subtilis by sacB promoter and signal peptide. Applied Microbiology and Biotechnology.2007;6 (73) : 1377-1381.

[2] Sung-Hou Kim, Chui-Hee Kang, Rosalind Kim, Joong Myung Cho, Yong-Beom Lee, Tae-Kyu Lee. Redesigning a sweet protein: increased stability and renaturability. "Protein Engineering, Design and Selection".1989;8 (2) : 571-575.