Team:Reading/Parts
The proposed function of this part is the production prepilin1, a pilus subunit, the theory of transforming in this part is that it will promote hyperpilation and increase the surface area in which electrons can be transferred from the plastoquinone pool to the anode. Making the cell ‘leak’ more electrons. This part also contains the pilA1 gene and the upstream Pcpc560 super-strong promoter, this will ensure the overproduction of the proteins necessary for hyperpilation. This biobrick part does have some complications however, see the safety section for more details.
PetF codes for ferredoxin, which is an iron-sulphur protein found in photosystem I. Ferredoxin transfers electrons to the ferredoxin reductase protein, which reduces the cofactor NADP to NADPH. This insertion is controversial, increasing the production of a protein which actively takes up electrons into a metabolic pathway will decrease electron leakiness, and therefore decrease the voltage given of by the fuel cell.
The PsaD subunit is a peripheral protein which helps to dock ferredoxin onto photosystem I2. Deletion of this gene will decrease the amount of ferredoxin in photosystem I decreasing the amount of electrons entering the electron pathway. However, deletion of this gene will have implications for the cell’s hardiness and survivability. Deletion of the PsaD protein could cause cell death and/or greatly impair growth.
Deletion of the PilT1 subunit will suppress pilus retraction, by reducing the activity of the ATPase responsible, again focusing on the hyperpilation of the Synechocystis. This will not lead to added growth of pili, but more the decreased subtraction of them once they are formed. This increases the surface area for which electron transfer can take place. However, Synechocystis is reliant on the PilT1 subunit for it’s motility and transformation competency. This will have direct consequences on the cell’s ability to reach nutrients and therefore grow, possibly meaning an even more exaggerated stumped growth and replication when nutrients start to become more scarce.
Synechocystis have an interesting characteristic in that it will undergo homologous recombination between its’ chromosome and plasmid in the homologous region. This is because Synechocystis is naturally transformable. Our gene deletions and insertions work by undergoing recombination in regions that they share homology with. The gene deletions will replace the gene with kanamycin resistance and the insertions simply place another copy of the desired gene into the Synechocystis genome.
- Yoshihara, S., Geng, X. X., Okamoto, S., Yura, K., Murata, T., Go, M., Ohmori, M., and Ikeuchi, M., (2001). Mutational Analysis of Genes Involved in Pilus Structure, Motility and Transformation Competency in the Unicellular Motile Cyanobacterium Synechocystis sp. PCC 6803. Oxford journals 63-73.
- Chitnis, V. P., Ke, A., and Chitnis P. R., (1997). The PsaD subunit of photosystem I. Mutations in the basic domain reduce the level of PsaD in the membranes. Plant physiology 1699-1705.
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