Part:BBa_K811003

INPNC 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 72
  Illegal NgoMIV site found at 405
  Illegal AgeI site found at 823
  
• 1000
  COMPATIBLE WITH RFC[1000]

Ice Nucleation Protein (N, C termini only). Surface display protein.

Usage and Biology

Ice nucleation protein (INP) is a protein found in Xanthomonas campestris pc. campestris BCRC 12846. It functions as, as its namesake suggests, causing ice nucleation and formation. However, recent studies have utilized INP for its surface display properties. In nature, the protein is anchored in the membrane through a glycosylphosphatidylinositol (GPI) anchor, a relatively rare occurance in prokaryotes.

The INP protein is composed of a N-terminal region that appears to interact with the phospholipid membrane, a C-terminus hydrophillic region that is exposed to the outside membrane, as well as a central 8, 16, or 48 amino acid motif that is responsible for INP's ice nucleation properties. However, this central amino acid motif is not necessary for INP's surface display properties. Therefore, scientists truncated the protein, retaining only the N (179 aa) and C termini (49 aa) to produce INPNC.

This truncated protein retains INP's membrane display abilities.

Characterization

INPNC was fused to a red florescent protein, mCherry, and cloned into the pET-26b(+) vector. The construct was then expressed in BL21 cells after induction with 1mM IPTG. The cells were lysed, and spun for 1 hour at 20000g to separate the membrane fragments from the lysate. The results were compared to Intein-mCherry, a soluble version of mCherry (Figure 1).

Figure 1: mCherry remains in the cell membrane pellet after centrifugation when compared to soluble intein-mCherry.

The UGent Belgium 2016 iGEM team codon optimised this part and used the sequence in BBa_K1896013.