Part:BBa_K2686002

Encapsulin protein with HexaHistidine insert

This is a BioBrick containing the sequence for Thermotoga maritima encapsulin, a bacterial protein nanocompartment which self assembles to form a 60-mer.

Usage and Biology

The part can be used to deliver cargo, both on the outer surface of the nanoparticle by fusing a peptide in between the 139/140 Amino Acids as well as the protein's C terminus. Cargo proteins can also be loaded inside the nano-cage using a tag binding to Encapsulin's interior surface. The protein is modified with an additonal amino acid sequence (GGGGGGHHHHHHGGGGG) between positions 43/44 granting it better stability and high heat resistance (Moon et al., 2014).

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal BglII site found at 77
  Illegal BglII site found at 492
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal SapI.rc site found at 426
  Illegal SapI.rc site found at 457
  

Results

The sequence was tested inside a a pet14 vector backbone inside an operon with a T7 promoter and a T7 terminator.

Self Assembly

The self assembly of the encapsulin 60-mer was first examined using SDS PAGE, where a high band is expected to form due to the high molecular weight and size of the 1.3 MDalton complex. Multiple gels were made, some containing the denatured cell free reaction mixture, others containing the same but after a variety of purification procedures.

SDS PAGE of the different encapsulin proteins expressed by iGEM EPFL 2018. Before (B) heat purification, the pellet after heat purification (P) and the supernatant after heat purification (S). From left to right: 1-3 Negative control (cell-free PURE expression without DNA), 4-6 HexaHis Encapsulin (BBa_K2686002) showing bands for the encapsulin multimer high on the gel lanes as well as the monomer around 31kDa, 7 HexaHis-OVA Encapsulin (BBa_K2686000) where bands are not easily discernible, 8 Ladder, 9 HexaHis-OVA Encapsulin (BBa_K2686000) where the monomer band is visible at 31kDa, 10-12 HexaHis Encapsulin (BBa_K2686002) where the bands for the 60-mer and monomer can be identified, 13-15 HexaHis-OVA Encapsulin (BBa_K2686000) where the bands can easily be discerned for both the monomer and 60-mer (note how the 60-mer band is more visible in the supernatant after heat purification, this suggests that the crowded cell free expression environment is not as conducive to encapsulin self assembly)

This confirms the successful assembly of HexaHis encapsulin into the 60-mer protein cage.

References

Moon, H., Lee, J., Min, J. and Kang, S. (2014). Developing Genetically Engineered Encapsulin Protein Cage Nanoparticles as a Targeted Delivery Nanoplatform. Biomacromolecules, 15(10), pp.3794-3801.