EXPERIMENTS
PHASE I: CONSTRUCTION OF THE COMPOSITE PARTS CBD cipA-BMP2 and CBD cipA-sfGFP
E.coli cells DH5α, BL21 (DE3) and BL21 (DE3) pLyss were prepared using the CaCl2 method, slightly modifying the one described in:
In order that the restriction enzymes EcoRI and PstI cleavage at the end of the gBlocks and the cohesive ends be generated, a PCR was run using the first forward 5'-ccggaattcgcggccgcttctag-3 'and reverse 5'-aaaactgcagcggccgctactag-3' to add the nucleotide bases to the N-terminal and C-terminal ends.
Experiment 3: Purification of the PCR products of the gBlocks
The objective of purifying the amplicons of the gBlocks was to use it in the process downstream of assembly 3A. The purification was carried out following the manufacturer's instructions (Invitrogen).
Once purified products were obtained from the CBD cipA gBlocks (driven by pLac promoter), BMP2 and sfGFP with basepairs added to the N-terminal and C-terminal ends, we proceeded to perform a fusion assembly to obtain the CBD fusion products cipA-BMP2 and CBD cipA-sfGFP. The methodology involved slight variations to the one described in the Open Wetware site Fusion Assembly.
The psb1c3-CBD vectors cipA-BMP2 and psb1c3-CBD cipA-sfGFP obtained by fusion assembly were transformed into E. coli DH5α, BL21 (DE3) cells by heath shock method according to the protocol described in Transformation.
Plasmid DNA was extracted from the bacterial transformation products for subsequent enzymatic digestions and PCR reactions to verify that the psb1c3-CBD inserts cipA-BMP2 and psb1c3-CBD cipA-sfGFP are correct.
The psb1c3-CBD plasmid products cipA-BMP2 and psb1c3-CBD cipA-sfGFP were digested with EcoRI and PstI to distinguish the size of the products by means of a 1% agarose gel electrophoresis.
PHASE II: CONSTRUCTON OF THE COMPOSITE PART CBD cipA-ELP
A PCR reaction was assessed to try amplifying the ELP[V-150] (transition temperature=28.6°C) from the commercial plasmid pET-24a-ELP[V-150] (Addgene). Numerous attempts were done using a set of primers; however, similar electrophoresis patterns with multiple diffuse bands were obtained.
OOnce primers was purified, the ELP550 obtained with the Forward 1 (5'-gaattcgcggccgcttctagatggccggcagttcagggggtgtag-3 ') and Reverse 2 (5'-ctgcagcggccgctactagtattaaccggtcggccagggaactcc-3') a PCR was run using the ForwardFu primers (5'-ccggaattcgcggccgcttctag-3 ') and ReverseFu (5'-aaaactgcagcggccgctactag-3') to add the nucleotide bases 5'-ccg-3 'and 5'-aaaac-3' to the N-terminus and C-terminus, respectively, and consequently leave space so that the enzymes EcoRI and PstI cut near the ends.
The PCR product was purified using the Quick Gel Extraction and PCR Purification Combo Kit according to the manufacturer's instructions (Invitrogen).
Once purified products were obtained from the CBD cipA gBlocks (driven by pLac promoter), BMP2 and sfGFP with basepairs added to the N-terminal and C-terminal ends, we proceeded to perform a fusion assembly to obtain the CBD fusion products cipA-BMP2 and CBD cipA-sfGFP. The methodology involved slight variations to the one described in the Open Wetware site Fusion Assembly.
See Transformation Protocol, Phase I.
Phase III: Construction of the cellulose production module
Due to the need of an induce mechanism we decided to use LacI cassette in our assemblies. To obtain this cassette we did a PCR reaction to amplify the LacI (promoter and ORF) from the commercial plasmid pET-24a-ELP[V-150] (Addgene).
In order to obtain specific sequences ends to be digested by the gibson assembly exonuclease, we used specific primers for each sequence to add overhanging ends to the sequence that must be ligated. This overhanging ends were added by PCR with specific conditions for each sequence.
Experiment 3: Purification of the PCR products of the gBlocks
The objective of purifying the amplicons of the gBlocks was to use it in the process downstream of assembly 3A. The purification was carried out following the manufacturer's instructions (Invitrogen).
Experiment 3: Linealization of the psb1C3 and psb1A3 plasmids.
To assemble all the parts to the plasmids with Gibson technique, we made the linearization and removal of the biobrick suffix and prefix from the psb1C3 and psb1A3 through PCR.
Several trials were carried out to assemble two vectors with the cellulose production module as planned. We faced with several problems that occurred during this trial and we could not obtain the assembled vectors that we wanted, but we obtained degraded DNA seen in electrophoresis and this could be due to the high concentration of GC at the ends of the sequences that interfer with the Gibson’s exonuclease cleavage activity.
Phase IV: Characterization of the binding strength of the CBD cipA with an endogenous C-terminal linker
Measurements of remaining fluorescences, after different washes, were done according to the protocol described by the Team Imperial 2014. Briefly, 20g of kombucha cellulose were blended with 125 mL. Then, 100 uL of the mixture were added into each well of a 96-plate reader and dried at 60º for 5.5 hours using a stove. A volume of 100 uL of CBD cipA-sfGFP protein extract was added into each well an incubated at 4ºC overnight. The fluorescence was measured after washing with different substances: dH20, 70% EtOH, Plasma and Stif.