Latest revision as of 23:41, 13 December 2019

pAR promoter for Chlamydomonas reinhardtii (Phytobrick)

This basic part contains the PAR promoter and a 5'UTR (A1-B2) for Chlamydomonas reinhardtii and was built as a part of the Kaiser Collection. Combined with a CDS, and a terminator, this level 0 construct leads to a high expression of a target protein. Especially in combination with the part BBa_K3002000(Spectinomycin resistance gene aadA) a high expression can be observed. As this part is a combination of the promoters HSP70A (upstream) and RBCS2, no heat shock is needed as a transcription activator ( Schroda, M.,2000).

Both MUT-PETase and MHETase show cytosolic expression and secretion when containing the cCA secretion signal using the PAR promoter. This promoter is a reliable regulatory element and allows high level expression of our genes of interest.

Effect of the SP20 module on the secretion efficiency of MHETase. (a) Level 2 MoClo constructs harboring the aadA selection marker, and the coding sequences for MUT-PETase and MHETase equipped with different secretion signals and a C-terminal SP20 tag for enhancing glycosylation. (b) UVM4 transformants containing the constructs shown in (a) 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. Transformants C12 (BBa_K3002202) and A27 (BBa_K3002200) served as positive controls. The black arrow points to MHETase, the white arrow to MUT-PETase.

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 different secretion signals. The constructs contain the coding sequence for a conventional 3xHA tag (C, K, L), or the 3xHA tag preceded by a SP20 tag to enhance glycosylation (M, N, O). (b) UVM4 transformants containing the constructs C (BBa_K3002202), K (BBa_K3002210), L (BBa_K3002211) and M (BBa_K3002212), N (BBa_K3002213), O (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 (BBa_K3002200) 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 Kaiser Collection

We are proud to present our very own MoClo part collection for C. reinhardtii - the Kaiser collection.

These 20 Parts are specifically designed and codon optimized for Chlamydomonas. Among them are regulatory elements, antibiotic resistances, resistance cassettes, secretion signals and tags. These parts were tested and optimized thoroughly and we can guarantee that they work 100%. With these, expression and secretion in Chlamy will be a success. 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 Kaiser 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. For this reason, we believe that our Kaiser Collection will strike a significant chord, as the future lies in standardized, easy to use methods such as MoClo. Visit our part collection site to get an overview over all parts of the Kaiser Collection

Sequence and Features