Part:BBa_K4439002

N-[AS]8-C

Recombinant Green Lacewing Silk Protein

Abstract

For the scope of our project, we designed a new recombinant silk protein N[AS]4C which adds hydrophobic protective properties to the insulative cellulose aerogel we produced, when coated on top of it. This part is inspired from the N[AS]8C recombinant protein previously produced in E. coli BL21(DE3) (Part:BBa K4439002). This part has been designed but not built and tested, as for the project we used the basic part (Part:BBa K4439001) to design the composite part mSA-N[AS]4C-CBD-10xHis (Part:BBa K4439007), which we successfully built and tested.

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]

Protein Characterization

• Silk proteins demonstrate interesting mechanical properties such as toughness, strength, lightweight, biodegradability and the possibility to produce different morphologies (fibers, foams, capsules, films). In addition to this, silk proteins comprise a high percentage of the amino acids glycine, serine and alanine which have an intermediate hydrophobicity.

• Green lacewing insects produce two types of silk: one produced by the larvae (cocoon) and the other by adult females (egg-stalk). The adult produced silk acts as a protective shelter and structural support for egg stalks, which are two ideal properties for a waterproof coating for our aerogel.

• In green lacewings, two serine- and glycine-rich silk proteins (Ma1XB1 and Ma1XB2) have been identified, both with highly repetitive core domains and small terminal domains. The core domain’s structure is rich in β-sheets with an approximative sheet-length of four amino acids between turns. These form repeating structural units constituting β-helices which have a significant positive correlation with the proteins’ surface hydrophobicity. A consensus motif for the core domain of Ma1XB2 (named [AS])had already been generated. Furthermore, a recombinant protein constituted by 8 repetitions of this [AS] module had also already been expressed in E. coli.

• N[AS]8C’s characteristics were further tested in various morphologies such as films, capsules, hydrogels and foams. When N[AS]8C formed a film, its hydrophobic properties were enhanced.

• Table 1 | N[AS]8C Recombinant Green Lacewing Silk Protein Characteristics

Modeling

To better see how the protein folding is, we modeled the structure of the N[AS]4C recombinant protein. One can better see the β-sheets of the core domain constituting β-helices.

Figure 1 | 3D model of the N[AS]8C protein.