Revision as of 00:46, 14 December 2019

L2 spectinomycin resistance + GLE_Mut-PETase + cCA_MHETase

The construct encodes the secretion signal GLE in front of the MUT-PETase gene and a cCA secretion signal upstream to the MHETase gene. As selection marker an aadA cassette is used. Constructs encoding the GLE secretion signal upstream to the MUT-PETase gene shows no detectable secretion of said protein. The construct containing GLE leads in comparison to the other secretion signals to a high yield of MHETase. Both enzymes are crucial for the degradation of PET into its terephthalic acid and ethylene glycol.

Overview of different level 2 MoClo constructs. We designed 35 different level 2 constructs by using the modular cloning system (MoClo) and transformed these into Chlamydomonas reinhardtii. These constructs contain promoters (PPSAD, PAR, PTub2), terminators (PSADter, RPL23ter, Tub2ter), and the coding sequences for selection markers (aadA, Hygro), tags (HA, His, SP20-HA, SP20-His), secretion signals (cCA, ARS, GLE) and the enzymes MHETase, wild-type PETase (WT-PETase), mutated PETase (Mut-PETase) and the mutated PETase from the iGEM team TJUSLS China 2016 (Mutate M).

The SP20 module increases the efficiency of protein secretion. (a) Level 2 MoClo constructs harboring the aadA selection marker, and the coding sequences for MUT-PETase and MHETase equipped with the secretion signals introduced in Figure 6. The constructs contain the coding sequence for a conventional 3xHA tag (C, K, L)(BBa_K3002202, BBa_K3002210, BBa_K3002211), or the 3xHA tag preceded by a SP20 tag to enhance glycosylation (M, N, O). See Figure 1 for the description of other parts. (b) UVM4 transformants containing the constructs C, K, L and M, N, O (BBa_K3002202, BBa_K3002210, BBa_K3002211, BBa_K3002212, BBa_K3002213, BBa_K3002214) were grown in TAP medium for seven days. Cells were centrifuged and the supernatant lyophilized, resuspended in 2xSDS buffer and analyzed by SDS-PAGE and immunoblotting with an anti-HA antibody. Transformant A27 introduced in Figures 4, served as positive control. The black arrow points to MHETase, the white arrow to MUT-PETase and the grey arrow to RPL1 (chloroplast ribosomal 50S protein L1). The RPL1 antibody was used to detect contamination from intracellular proteins.

The Chlamy Yummy Project Collection

We are proud to present our MoClo part collection for C. reinhardtii - the Chlamy Yummy project collection.

These 67 parts are all parts used during our project and were specifically designed and codon optimized for Chlamydomonas. Among them are basic parts (L0) of a novel mutant of the PETase (BBa_K3002014), the wildtype PETase and MHETase as well as a variety of functional composite parts (L1+2). Containing different tags as well as selection markers, this collection serves as a perfect base for plastic degradation projects with Chlamydomonas. These parts were tested and optimized thoroughly and we can guarantee that they work 100%. Because this is a MoClo collection, the parts are highly standardized for worldwide application. The combination with other part collections works fast and easy. While in MoClo, nomenclature is a bit different from the iGEM BioBricks, it is quickly explained:

Level 0 parts are equivalent to basic parts, e.g. Promoters, coding sequences, etc.

Level 1 parts are combinations of basic parts and usually form functional transcription units.

Level 2 parts are combinations of Level 1 parts, in case you want to transfer multiple transcription units at once. For example, you can pair your gene of interest with a selection marker.

The great thing about the Chlamy Yummy Collection and MoClo is that the ligation works in a one pot, one step reaction, as the Type IIs restriction enzymes cut out their own recognition sites. This way, multiple constructs can be combined linearly in a fixed order to create complex structures. This is ensured by the standardized overlaps that assign the parts one of 10 positions in the final constructs. After trying MoClo once, you won’t go back to traditional ligation. It is incredibly easy and reliable. Visit our parts site to get an overview over all parts.

Sequence and Features