Team:DTU-Denmark/Results-melA
melA Expression
The melA gene from Rhizobium etli encodes a tyrosinase involved in the first step of the melanin synthesis, producing dopaquinone. To increase the resistance of our fungi to UV radiation we were interested in increasing expression of melanin, as the pigment has previously been reported to protect against UV radiation. (1)
Assembly
melA was synthesized de novo by IDT and assembled with PtrpC into the pSB1C3 backbone by 3A assembly. The cauliflower mosaic virus (CaMV) terminator was then added by 3A assembly. Correct transformants were identified by colony PCR and Sanger sequencing using the verification primers, VF2 and VR (data not shown). The plasmid map of the biobrick can be seen in fig. 1:
Fig. 1: Plasmid map of BBa_K2799014
Transformation
A. oryzae protoplasts were transformed with the melA coding biobrick BBa_K2799014 and plated on transformation media w. 0.6 mg/mL L-tyrosine. After ~3 days of growth almost all colonies exhibited wild type phenotypic behaviour and morphology, which is to be expected as there is no selectable marker for successful transformants. However, one area of colony exhibiting darker color than the surrounding colonies might be indicative of a successful transformation. We have replated the colony to further assess whether the potential transformant exhibits consistent darker color, in which case we will validate the insertion of our biobrick by PCR and subsequently sequencing.
Fig. 2: Plate with colony of interest from plating of melA transformants.
Conclusion
We have successfully assembled two melA cassettes, each with a different promoter.
As of now, we have apparent transformants, which suggests integration of our cassette into the A. oryzae genome. If this can be verified, it opens the opportunity to fabricate fungal materials with the added benefit of melanin inducing UV resistance.
Appendix: Primer list
(1) Jing, G.; Sheng-Bing, Y.; Xia, W.; Xiao-Juan, W.; Ping, S., Ping, Z., Xiang-Dong, C. Protective action of bacterial melanin against DNA damage in full UV spectrums by a sensitive plasmid-based noncellular system. Journal of biochemical and biophysical methods. Elsevier, 70(6), 2008, 70, 1151-1155. doi: 10.1016/J.JPROT.2007.12.013.