Part:BBa_K844001

Spider Silk 1x 1E Subunit "U" (native sequence)

Spider silk subunit (1x) native sequence; contains one elasticity domain and one strength domain.

IMPORTANT NOTE: This part uses Assembly Standard #23 (Silver Fusion) scar sites, which the sequence data below and on composite parts using this part will not reflect this scar sequence (it shows Assembly Standard #10 scars).

Usage and Biology

The sequence for this subunit was derived from the 1E silk subunit from Brooks et al. (2008), which is based on the native sequence of the MaSp2 silk gene in Argiope aurantia. The 1E silk subunit contains codons for only six amino acids in the following proportions: glycine (40%), alanine (17.5%), glutamine (15%), proline (15%), serine (7.5%), and tyrosine (5%). The native Argiope aurantia codon usage profile is significantly different from E. coli ’s and the GC% of the DNA molecule itself (75%) is significantly different from the average GC% of native E. coli genes (51%). These features can make the native form of the gene difficult and slow to produce for the ribosomes in the cell as the necessary tRNA molecules are present in lower concentrations in E. coli and the genetic machinery of E. coli is not adapted to opening DNA of high GC% when making mRNA, and thus lower amounts of spider silk mRNA are produced.

This part is designed for use as an internal subunit in a longer spider silk construct. This part should be preceded by the BBa_K844005 silk subunit, which is identical to this subunit but contains an added Met (ATG) start codon upstream, and should be followed by either more repeats of this subunit or end with a BBa_K844000 part, which contains a 10-Histidine tag and a double stop codon (TAATAA).

The silk subunit contains three main domains: an elasticity domain, a linker domain, and a strength domain. The elasticity domain contains sequences coding for beta-helices and beta-spiral in the protein; these structures increase the elasticity of the spider silk. The linker domain joins the strength and elasticity domains together. The strength domain will form beta-sheets and strengthen the silk fibers by cross-linking silk strands.

Silk Subunit Amino Acid Composition:

Related parts:

BBa_K844002 – the native spider silk subunit with two elasticity domains and one strength domain (no sequence manipulation)

BBa_K844005 – this spider silk subunit with an added Met (ATG) start codon at the 5’ end

References:

Brooks AE, Stricker SM, Joshi SB, Kamerzell TJ, Middaugh CR, and Lewis RV. 2008. Properties of synthetic spider silk fibers based on Argiope aurantia MaSp2. Biomacromolecules 9:1506–10.

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
  INCOMPATIBLE WITH RFC[25]

  Illegal NgoMIV site found at 19
  
• 1000
  COMPATIBLE WITH RFC[1000]