Difference between revisions of "Part:BBa K4390073"

Revision as of 09:01, 12 October 2022

FAST-PETase

This part is not compatible with BioBrick RFC10 assembly but is compatible with the iGEM Type IIS Part standard which is also accepted by iGEM.

FAST-PETase is a mutant form of the PETase, which has faster activity. We immobilised this part to Silica beads as part of our cell free PET biodegradation device.

Usage and Biology

FAST-PETase is an engineered mutant of PETase (290 amino acids) with (S121E/D186H/R224Q/N233K/R280A).

PETase was discovered in 2016 in Ideonella sakaiensis, which uses PET as a single carbon source (Yoshida, 2016). The PETase hydrolyses PET polymers and produces mono(2-hydroxyethyl)-TPA (MHET) majorly, and minorly two final products shown below: terephthalic acid (TPA), and ethylene glycol (EG) (Joo et al., 2018). However, since only a very small amount of MHET can be continued to be hydrolysed to TPA by PETase, we need to add MHETase to the device to increase TPA yield and purity in our cell-free device (Puspitasari, Tsai and Lee, 2021).

From literature search, we learnt Lu's team has enhanced the activity of PETase with CNN-based machine learning algorithms and developed FAST-PETase, the most efficient enzyme available today with five mutations comparing to wild-type PETase (S121E/D186H/ R224Q/N233K/R280A). Untreated post-consumer PET from 51 different thermoformed products is almost always completely degraded by FAST-PETase at 50 ºC for periods ranging from 24 h to 1 week. FAST-PETase can also depolymerize the untreated amorphous fraction of a commercial water bottle and an entire heat pre-treated water bottle at 50 ºC. For highly crystalline PET, a simple pre-treatment (e.g., melting) allows the PET to be feasibly degraded.

Design

The FAST-PETase (BBa_K4390073) encode the peptide sequence of PETase with mutations on (S121E/D186H/R224Q/N233K/R280A) and 2 additional base pairs to fit in JUMP assembly O part design. The codon is optimized for BioBrick and JUMP assembly.

Characterization

The FAST-PETase (BBa_K4390073) was used to assemble the following Lv.1 JUMP assembly for activity assessment and immobilization.

Sequence and Features

References

Yoshida S, Hiraga K, Takehana T, Taniguchi I, Yamaji H, Maeda Y et al. A bacterium that degrades and assimilates poly(ethylene terephthalate). Science. 2016;351(6278):1196-1199.

Joo S, Cho I, Seo H, Son H, Sagong H, Shin T et al. Structural insight into molecular mechanism of poly(ethylene terephthalate) degradation. Nature Communications. 2018;9(1).

Puspitasari N, Tsai S, Lee C. Class I hydrophobins pretreatment stimulates PETase for monomers recycling of waste PETs. International Journal of Biological Macromolecules. 2021;176:157-164.

Lu H, Diaz D, Czarnecki N, Zhu C, Kim W, Shroff R et al. Machine learning-aided engineering of hydrolases for PET depolymerization. Nature. 2022;604(7907):662-667.

Improvement on BBa_K3946023 by Edinburgh-UHAS_Ghana 2022

We improved upon the Dou-PETase part (Part:BBa_K3946023) with the FAST-PETase part (Part:BBa_K4390073).

PETase-silica tag fusion protein Activity Test

We assessed the various PETase activities using a para-nitrophenol-butyrate (pNPB) assay, since PETases can hydrolyse pNPB into para-nitrophenol (pNP), which strongly absorbs at 415 nm. pNPB is not the PETase’s true substrate, but this preliminary assay is still representative of PETase activity. Figure 1 shows that untagged FAST-PETase has higher activity than Dou-PETase in this assay. Hence, FAST-PETase is an improvement over Dou-PETase for degradation of PET. The data also shows that PETase activity is diminished, but still exists when immobilised on silica beads, as the activity is higher than SHuffle E. coli lysate.