Designing, cloning and amplification of pDream2.1/MCS/CII-6 recombinant plasmid which includes a mexican scorpion Centruroides limpidus limpidus CII-6 gene

Biologically active molecules present in the venom of several species of scorpion, have shown potential against various diseases, including cancer. It has been reported that several toxins can block ion channels present in the membrane of several cancer cell lines, through action potential, altering their cell function, cell cycle arresting, and inducing apoptosis death pathway. The use of SciForum the sequence of Cll-6 gene present in the genome of the Mexican scorpion Centruroides limpidus limpidus encoding a beta-toxin-locker of Na + channels by action potentials is proposed. This molecule has not been evaluated to determine if it has potential as an anti-cancer agent. In this paper the in silico design of recombinant molecule pDream2.1/MCS/CII-6, including the CII-6 gene into the polylinker site and identification by molecular biology techniques. Our results confirm a fragment of 316 base pairs, by digestion with BamH1 and Kpn1 enzymes, PCR, and the sequenced of amplicon, the alignment with CII-6 sequence reported in the GenBank database, showed 99.6% similarity and identity. The recombinant plasmid, could be used to assess potential as anti-having cancer agent on several cancer cell lines.


Introduction
; (Soroceanu et al., 1998(Soroceanu et al., , 1999. It has been reported that the growth and invasion of several cancers is associated with dysregulation of ion channels (Le Gueneec et al., 2007), a necessary mechanism that requires Na+, K+ and Cl-ions to facilitate growth and invasion of a tumor cell (Mao et al., 2008), therefore it is suggested that, related toxins to ion channels in the membrane cell can be used to treat certain types of cancer (Mamelak et al., 2007) A potential resource is the Centruroides limpidus limpidus scorpion species (CII), the second in importance in Mexico by medical reports of scorpionism (Ponce and Francke, 2004). The components of the scorpion venom are molecules physiologically active, the most important are toxins that interact selectively and specifically with Na + , K + (Rodriguez de la Vega and Possani, 2004;2005), Ca2 + and Clion channel, presents in the cell membrane of mammalian, insect and crustaceans.
CII-6 is a beta-toxin of 85 aminoacids, with a molecular mass of 9,323 Daltons, CII-6 belongs to the superfamily of scorpion toxins long chain (4 C-C), inhibitors of Na + ion channels, which is expressed in high concentrations and secreted in the venom gland of this scorpion, this toxin binds independently of the voltage on the site-4 of Na + ion channel (NAV), and changes the voltage activation to more negative potentials, affecting the activation of Na + ion channel and promoting spontaneous and repetitive shots (Coronas and Possani, 2002; Uniprot, 2016).
To date, not been explored the CII-6 molecule as anti-cancer agent, however, there are reports of toxins from the venom of different scorpions with affinity to Na + ionic channels, can inhibit, control and interact with various stages of metastatic cascade, as has been evidenced in several aggressive for its high levels of expression carcinomas (Gellet et al., 2009).
In the present work, is reported the in silico design of recombinant molecule pDream2.1/MCS/CII-6 containing the CII-6 sequence, present in the genome of C. l. limpidus, as well as their cloning, restriction enzyme digestion, amplification by PCR and sequencing. The amplicon sequenced and aligned with the sequence reported in the database GenBANK corresponding to the CII-6 gene of Centruroides limpidus limpidus encoding for a beta-toxin, Na+ channel modifier. Both show 99.6% of identity and similarity ( Figure 4) This molecule, may be used to test effect on several cancer cell lines, which is the very purpose of the investigation. It is noteworthy that the experiments were already started and show promising results. .

Design of pDream2.1/MCS/CII-6
Was designed in silico the recombinant molecule pDream2.1/MCS/CII-6, incorporating into the multicloning site of commercial expression vector pDream2.1/MCS (GenScript, USA), the sequence of CII-6 gene (GenBank : AF491132) flanked by two sites for restriction enzyme EcoR1 and Kpn1, it was sent to company GenScript, for synthesis. The product freeze-dried was resuspended in 200 µl of nuclease-free water at 42 ° C.

Preparation of competent cells
Bacteria frozen Escherichia coli strain DH5-α was inoculated into 20 ml of LB medium (Luria-Bertani, Sigma SLBB9243) without antibiotic and incubated for 16 hours at 37 ° C with constant stirring (200 rpm), later, 1 ml of bacterial growth was cultured in a Falcon tube of 50 ml (Axygen Scientific, Cat. 431621) containing 10 ml of LB medium and incubated for 4 hours at 37 ° C with stirring, and was measured optical density in a spectrophotometer (Epoch: 1209284) at 450 nm.
The bacterial culture was transferred to two 50 ml Falcon tubes prechilled and centrifuged at 3000 rpm x 10 min at 0 ° C, the supernatant was decanted, and the pellet was resuspended in 1 ml of cold CaCl2 (0.1M), the tubes were centrifuged at 3000 rpm x 10 min at 0 ° C. Subsequently was added again 1 ml of cold CaCl2 (0.1M) and aliquoted into sterile vials precooled (Sambrook and Fritsch, 1989).

Transformation of competent cells by heat shock
Was added 1 µl of recombinant plasmid pDream2.1/MCS/CII-6 to one vial of competent cells and it was incubated for 30 minutes on ice placed, immediately in water bath at 42 ° C for 45 seconds, finally in ice for 2 minutes. Was added 900 ml of LB medium and was incubated for 1 hour at 30 ° C with stirring (220 rpm) (Sambrook and Fritsch, 1989).

Cloning and replication of Escherichia coli strain DH5-α/pDream2.1/MCS/CII-6
30 µl of cells transformed, were grown in dishes LB-agar with ampicillin (100 mg/ml, PentrexilR Bristol-Myers Squibb) and incubated at 37 ° C for 16 hours (Sambrook and Fritsch, 1989). A colony from plate with transformed bacteria growing, was inoculated into 5 ml of LB medium with ampicillin and incubated at 37 ° C for 16 hours with constant stirring.

Extraction and purification of pDream2.1/MCS/CII-6
The extraction of plasmid DNA was performed with the kit GeneJET Plasmid Miniprep (Thermo Scientific Cat. # K0502) following the manufacturer's instructions. Briefly, Escherichia coli strain DH5-α/pDream2.1/MCS/IIC-6 after 16 hours in culture, was centrifuged at 3000 rpm for 10 minutes and the supernatant was discarded, the pellet was suspended with 250 µl of the solution resuspension and transferred to a sterile vial, then, were added 250 µl of Lysis Solution and mixed by inversion 5 times, after, were added 350 µl of Neutralizer Solution and again mixed by inversion. The tube was centrifuged at 13,500 rpm for 5 minutes and the supernatant was transferred to a GeneJET column, and centrifuged at 12,500 rpm for 1 minute, the filtrate was discarded, subsequently, 2 washed were performed, with 500 µl of Wash Solution and centrifuged for 1 minute at 13,500 rpm. The filtrate was discarded and one additional step of drying by centrifuging for 1 minute was performed. Finally, the column was transferred to a new microcentrifuge tube and 50 µl Elution Buffer was added, allowed to incubate for 5 minutes at room temperature and centrifuged for 2 minutes at 14,000 rpm. The extraction yield of DNA was quantified in spectrophotometer (Nanodrop Quawell 5000) at 600 nm.

Sequencing of amplicons (CII-6)
The PCR products were sequenced by the Sanger method by the company Genscript (Genscript Corporation, Piscatway, NJ, USA;) the received sequence was aligned with MEGA program (6.06) with the sequence CII-6 gen of the scorpion Centruroides limpidus limpidus reported in GenBank.

Conclusions
The design and assembly of pDream2.1/MCS/CII-6, were performed correctly, was verified a fragment of 316 bp approximately by digested with restriction enzymes after cloning. PCR and sequencing of amplicons, confirm the insert of CII-6 gen of C. l. limpidus, such molecule therefore can be used for various experiments.