[2] Gene expression is regulated by a circadian clock and the organism can effectively anticipate transitions between the light and dark phases.
[4] Cyanobacteria have colonized a wide diversity of habitats, including fresh and salt water ecosystems, and most land environments.
[5] Phylogenetically, Synechocystis branches off later in the cyanobacterial evolutionary tree, further from the ancestral root (Gloeobacter violaceus).
[6] Synechocystis, which is non-diazotrophic, is closely related to another model organism, Cyanothece ATCC 51442, which is a diazotroph.
[8] Cyanobacteria are model microorganisms for the study of photosynthesis, carbon and nitrogen assimilation, evolution of plant plastids, and adaptability to environmental stresses.
[2] Bubbling with carbon dioxide enriched air (1–2% CO2) can increase the growth rate, but may require additional buffer to maintain pH[2] Selection is typically performed by antibiotic resistance genes.
[11] For long term storage, liquid cell cultures should be stored in a 15% glycerol solution at -80 degrees Celsius.
PCC6803, sub-strain ATCC 27184 can live heterotrophically in the dark on the carbon source glucose, but for yet unknown reasons requires a minimum of 5 to 15 minutes (blue) light per day.
[18] The CRISPR-Cas (Clustered Regularly Interspaced Short Palindrome Repeats – CRISPR associated proteins) system provides adaptive immunity in archaea and bacteria.
All cyanobacteria are lacking the type II system, which has been widely adapted for genetic engineering purposes across many species.
[20] The beta subunits are responsible for binding the RNAP to the DNA, preventing premature dissociation.
In Escherichia coli, the beta "clamp" first binds loosely and tightens as the RNAP approaches the start codon (AUG).
In E. coli, a repressor binds the DNA operon and dislodges RNAP due to the loosely bound beta clamp, whereas in Synechocystis, the RNAP is tightly bound leading the reverse phenomenon where the repressor is knocked off the DNA.
[2] RSF1010 is a mobilization plasmid that facilitates conjugation between cells, allowing the horizontal gene transfer of DNA.
[25] Additionally, RSF1010 encodes its own replication machinery, so that it does not depend on its host to possess the necessary proteins and assorted factors.
Type I promoters consists of a consensus -35 and -10 region (Pribnow box)[20] upstream of the gene start site.
PCC6803 promoters that have been used in synthetic constructs, although this leads to cross talk and non-orthogonal or non-specific gene expression.
As noted above in RNA Polymerase and Sigma Factors, the beta clamp proteins within the RNAP complex have a higher initial binding affinity in Synechocystis sp.
[21] Thus promoters that turn on/off in response to small binding molecules are less effective in Synechocystis since the RNAP can knock them off the DNA strand.
[21] Huang and Lindblad 2013 created a library of modified pTet promoters with varying levels of repression and dynamic range in the glucose tolerant Synechocystis sp.
[16] Another option are promoters that are inducible by heavy metals, such as: zinc, cadmium, cobalt, arsenic, nickel and chromium.
These promoters are not ideal, as metal ions are critical in Synechocystis’ metabolic pathways and altering concentrations can lead to compounding undesired side effects.
[28] Additionally, working with these promoters produces waste contaminated with heavy metals, increasing disposal costs The ribosome binding site (RBS) is the location where a ribosome binds a strand of mRNA and begins translation.
[30] The EROEI is not advantageous as numerous large, closed loop bioreactors with ideal growth conditions (sunlight, fertilizers, concentrated carbon dioxide, oxygen) need to be constructed and operated, which consumes fossil fuels.