Team:Aberdeen Scotland/Parts/ 2004


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Team:Aberdeen Scotland/Parts -

Background to Parts Design

Ice Nucleation Protein (INP) Yellow Florescent Protein (YFP) FLAG-tag K1352004 is a part which has a FLAG-tag octapeptide flanked by a multiple cloning site (MCS) inserted into Bba_K523013 (K523013 expresses ice nucleation protein (INP) fused to yellow florescent protein (YFP) by a linker); specifically, on the end of the C-terminus of yellow florescence protein (YFP) and is in the same reading frame as INP+YFP. The FLAG-tag is a BglII restriction site, followed by a FLAG octapeptide, followed by a HindIII restriction site; the sequence of which is as follows; the octapeptide is uppercase, the restriction sites are lowercase: (agatctGATTATAAAGATGATGATGATAAAaagctt) Attaching a FLAG-tag to the end of YFP means that it will be expressed on the surface of the cell, the purpose of this is to allow the rapid insertion (via the MCS) of polypeptides (an antigen for example) to the C-terminus end of INP+YFP; this allows the surface expression of said polypeptide. For the 2014 Aberdeen iGEM project, this part was intended to be used as a trypanosome antigen displayer. Creation of INP-YFP-FLAG fragments followed by InFusion cloning Four infusion primers (primers with one homologous half (lower case) to the template, and one “overhang” half (upper case), the last 15 nucleotides of which is homologous to another DNA fragment) were designed. “INP-VEC-F” (CGCGGCCGCTTCTAGAttaatacgactcactataggg) “INP-FLAG-R” (AAGCTTTTTATCATCATCATCTTTATAATCAGATCTcttgtacagctcgtccatgc) “INP-FLAG-F” (AGATCTGATTATAAAGATGATGATGATAAAAAGCTTtaataatactagcaacatatcataacggagtg) “INP-VEC-R” (AGCGGCCGCTACTAGTtataaacgcagaaaggccc) Two INP-YFP-FLAG fragments were created by PCR amplification, both use K523013 as the template, the first uses “INP-VEC-F” and “INP-FLAG-R” primers, the second uses “INP-VEC-R” and “INP-FLAG-F” primers. The Clontech InFusion kit was used to recombine the two INP-YFP-FLAG fragments with pSB1C3 backbone (cut with Xba1 and Spe1); this kit was followed according to the manufacturer’s instructions. Confirmation of K1352004 DNA construct and the insertion of a MCS

Fig.1     Restriction digest verification of plasmids K1352004, K523013, and “INP-YFP-His” (a previously created plasmid which identical to K1352004 except that the FLAG tag is a 6xHis tag)

Fig.2    Restriction digest verification of plasmid K1352004

Figure 3, Panel A;     a composite fluorescence image – brightfield micrograph of a pSB1A3-transformed liquid cell culture (negative control) exhibiting no fluorescence as expected.

Figure 3, Panel B;     a composite fluorescence image – brightfield micrograph of a K523013-transformed liquid cell culture exhibiting yellow fluorescence as expected.

Figure 3, Panel C;     a composite fluorescence image – brightfield micrograph of a K1352004-transformed liquid cell culture exhibiting yellow fluorescence.

Figure 4;     Western Blot to confirm the presence and size of the translated INP-YFP-FLAG protein

Antigen 43 (Ag43), the product of the flu gene, is a cell-surface autotransporter protein found in Escherichia coli. It is expressed at about 50, 000 copies/cell and is initially synthesised as a precursor of 1039 amino acids. Upon removal of the signal peptide, the protein is transported to the cell surface and is composed of an α subunit (499 amino acids) at the N-terminus and a β subunit (488 amino acids) at the C-terminus. Ag43 is mainly known to induce cell-to-cell aggregation and be involved in biofilm formation. However, as the necessary information required for auto transportation resides in the protein itself, the main of our project was to use it as a platform for displaying specific peptides on the surface of E. coli.