Team:NTNU-Trondheim/Experiments and Results

A very clear band with the size of around 1200-1300 bp was found in one of the samples. This is a smaller DNA fragment compared to the known gene sequence of about 1700 bp. Since the size of Protein G is known to vary among the different strains, we can still conclude that our PCR-product is Protein G. The PCR product with the genomic DNA sample 1 as template and F_tat_PrG and R_pl.b_PrGstop (see table below) as primers is most likely Protein G.
Table: Primers applied in creating the tat_ProteinG construct. Lowercase letters indicate DNA that anneal to the template whereas the uppercase letters indicate DNA that serves as an overhang. {|class="table table-bordered table-hover" style="margin: 1em auto 1em auto; width: auto;" !Amplifing !Primer !Sequence |- |Protein G |F_tat_PrG | CGACGTGCGACTGCGGCGCAAGCGgttgactcaccaatcgaagatacccc |- |Protein G |R_pl.b_PrGstop |GCCTTTCGTTTTATTTGATGCCTGG ttagtcttctttacgttttgaagcgac |} ====Attaching tat signal sequence by PEC==== For attachment of the tat DNA fragment to the Protein G PCR fragment Polymerase Extension Cloning ([https://2013.igem.org/Team:NTNU-Trondheim/Protocols#PEC PEC]) was applied. After the PEC PCR reaction the product was run on a agarose gel together with the PCR product of Protein G without the tat attached.

[[file:tatPrG_PrGref.jpg|400px]] figure: From the left; Protein G with tat attached and Protein G without tat. The PEC product is clearly a little bit longer then the Protein G PCR product without tat attched. This indicates that PEC was successful. ====Cloning by Direct Transformation and SLIC==== The tat_ProteinG fragment was mixed with the same plasmid backbone PCR product that was produced for the tat_GFP_l_RFP construct in varies different cloning reactions: [https://2013.igem.org/Team:NTNU-Trondheim/Protocols CPEC], [https://2013.igem.org/Team:NTNU-Trondheim/Protocols SLIC] and [https://2013.igem.org/Team:NTNU-Trondheim/Protocolsdirect transformation]. 18 different reactions was run. The cloning products was transformed into ‘’E.coli’’ DH5α cells. The plasmids were then [https://2013.igem.org/Team:NTNU-Trondheim/Protocols isolated] and a conformation PCR was executed with F_pl.b_tat and R_pl.b_PrGstop as primers. The conformation results can be viewed in the figure below: [[file:conf.PCR on tat-PrG.png|400px]] figure: First row contains tat_ProteinG samples 1-9, second row contains tat_ProteinG samples 10-18). All of the samples that had a PCR product of the expected size of 1200-1300 bp (10 samples) was sent for sequencing. The sequencing results showed that two of the constructs had approximately the DNA sequence they should have. However, these constructs, named Dt8 (created by direct transformation) and S3 (created by SLIC) had an addition and a deletion of a guanine residue in the beginning of the tat sequence, respectively (see figures below). These errors would create a frame shift that would produce a dysfunctional Protein G. [[file:tatPrG DT8.jpg|400px]] figure: Aligment of tat_ProteinG DT8 (left) and S3 (right). There is one segment missing in our ProteinG, as is expected as the ProteinG variant that we are dealing with is a shorter than the [http://www.ncbi.nlm.nih.gov/nuccore/X06173 registered gene sequence]. There is however, an addition of a guanine residue in the beginning of the tat-sequence in the DT8 sample and a deletion at the same site in the S3 sample, which will cause a frame shift resulting in a non-functional protein product. Because it is only possible to sequence approximately 1000 bp, we don't have all of the sequence of our tat_ProteinG construct. ====Fixing deletion by PCR==== In order to correct the Guanin deletion/addition a PCR was run on the DT8 and S3 sample with the primers F_pl.B_tat and R_pl.b_PrGstop. The PCR products was cloned together with the same plasmid backbone in a direct transformation. Plasmids from the transformed ''E.coli'' DH5α cells were [https://2013.igem.org/Team:NTNU-Trondheim/Protocols isolated] and sequenced. One of the new construct originated from PCR with the S3 sample has the desired DNA sequence. ====Sequencing and Characterization==== The rest of the tat_ProteinG was sequenced (see figure below) [[file:PrG_R.jpg|500px]] Figure: Alignment of the full tat_ProteinG construct. The Protein G gene from the ''Streptococcus dysgalactiae ssp equisimilis'' sample we collected from the hospital is clearly missing two bigger segments compared to the [http://www.ncbi.nlm.nih.gov/nuccore/X06173 known gene sequence]. We conclude that this is Protein G as the rest of the sequence aligns well. Vesicles were isolated from ‘’E.coli’’ ER2566 cells by the [https://2013.igem.org/Team:NTNU-Trondheim/Protocols#Small-Scale_Vesicle_Preparation vesicle isolation protocol]. SDS-PAGE was done on both samples with one diluted sample (1:2) and one undiluted sample (1:1) for both. [[file:vesicles_PrG.jpg|400px]] Figure: SDS-PAGE , with the ladder Precision Plus Protein^TM Unstained Standards. First sample is a diluted (1:2) sample of vesicles from cell with tat_ProteinG construct, second sample is the same but undiluted (1:1). The bands are not as visible as with the naked eye. There are no detectable additional bands in the tat_ProteinG samples compared to the wild type ER2566 (see SDS-PAGE figure above) sample, indicating that there is no Protein G in the vesicles. ===Pm/XylS promoter system===