Coding

Part:BBa_K4247011:Design

Designed by: Matteo Soana   Group: iGEM22_UCopenhagen   (2022-09-24)
Revision as of 11:00, 7 October 2022 by Akila (Talk | contribs) (→‎References)


Minispidroin_NT-4rep-CT


Assembly Compatibility:
  • 10
    INCOMPATIBLE WITH RFC[10]
    Illegal PstI site found at 469
    Illegal PstI site found at 475
    Illegal PstI site found at 490
    Illegal PstI site found at 544
    Illegal PstI site found at 562
    Illegal PstI site found at 721
    Illegal PstI site found at 727
  • 12
    INCOMPATIBLE WITH RFC[12]
    Illegal PstI site found at 469
    Illegal PstI site found at 475
    Illegal PstI site found at 490
    Illegal PstI site found at 544
    Illegal PstI site found at 562
    Illegal PstI site found at 721
    Illegal PstI site found at 727
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    INCOMPATIBLE WITH RFC[23]
    Illegal PstI site found at 469
    Illegal PstI site found at 475
    Illegal PstI site found at 490
    Illegal PstI site found at 544
    Illegal PstI site found at 562
    Illegal PstI site found at 721
    Illegal PstI site found at 727
  • 25
    INCOMPATIBLE WITH RFC[25]
    Illegal PstI site found at 469
    Illegal PstI site found at 475
    Illegal PstI site found at 490
    Illegal PstI site found at 544
    Illegal PstI site found at 562
    Illegal PstI site found at 721
    Illegal PstI site found at 727
  • 1000
    COMPATIBLE WITH RFC[1000]


Design Notes

It is difficult to synthesise the entire DNA sequence of minispidroins due to the repetitiveness of the central motifs. So, at the UCopenhagen team, we have decided to split the protein into the N-terminus and C-terminus in an expression plasmid and the repetitive part in another cloning plasmid which is easier to produce. The DNA sequence coding for the N- and C-terminus was designed to be separated by a spacer containing two BsaI sites while the repetitive (central) part of the final protein would have 2 BsaI sites on each end. In this way, the repetitive sequence was added in between the N and C terminus to get a whole protein.


We decided to produce a protein similar to Minispidroin_NT-2rep-CT (composite part BBa_K247007) because higher repeats in spider silks were shown to give better fibre performance. Compared to the parts with only 2 central repeats (BBa_K4247004, BBa_K4247007), the process for achieving 4 central repeats was the same, but we used a cloning vector that had the full 4 repeats rather than only 2 as a donating vector in Golden Gate Cloning.


The DNA sequence coding for the minispidroin protein was also contained in a pET24 expression vector having a T7 promoter,terminator and KAN resistance gene. Some proteins are expressed better if they have the His-tag in the N-terminus or vice versa. Our expression vector - pET24 (+) - has a 6x His-tag in the C-terminus.


Since the type IIS assembly compatibility system forbids the presence of a BsaI recognition site within the sequence of a part, we have chosen to split the N- and C-terminus into 2 basic parts here in the Registry. Further, this sequence was codon optimised as per E.coli's codon bias.

Source

The sequence of this composite part is obtained from the following basic parts: BBa_K4247000 (Minispidroin_NT), 2x BBa_K4247001 (Minispidroin_2rep) and BBa_K4247002 (Minispidroin_CT).

References

Andersson, M., Jia, Q., Abella, A. et al. Biomimetic spinning of artificial spider silk from a chimeric minispidroin. Nat Chem Biol 13, 262–264 (2017). https://doi.org/10.1038/nchembio.2269

Strickland, M., Tudorica, V., Řezáč, M. et al. Conservation of a pH-sensitive structure in the C-terminal region of spider silk extends across the entire silk gene family. Heredity 120, 574–580 (2018). https://doi.org/10.1038/s41437-018-0050-9