Contents
- 1 Compiled Protocols for TcdC Plasmids Design
Compiled Protocols for TcdC Plasmids Design
I. C. Difficile gDNA Extraction Using Phenolchloroform
Materials
Resuspension Buffer
- 10 mM Tris-HCl, pH 8.0
- 20% (w/v) Sucrose
Lysis Buffer
- 10 mM Tris-HCl, pH 8.0
- 1mM EDTA
- 1% (w/v) SDS
RNase A (10mg/mL)
- 10 mg bovine pancreating RNase A
- 10 mM Tris, pH 8.0
- 500 mM NaCl
- 850 uL water
- Heated to 95 C until use
Protocol
- 10 mL of overnight culture was pelleted at 5000 rpm for 5 minutes
- Pellets were resuspended in 1 mL of resuspension buffer.
- 9 mL of lysis buffer was added to resuspended pellet.
- Cell suspension was incubated at 37 C for 1 hour, shaking at 260 rpm.
- Crude cell lysate was extracted with an equal volume of phenol chloroform.
- Aqueous phase was recovered to a new tube and 25 ug RNase A was added, crude lysate was incubated at 37 C for 20 minutes.
- Crude lysate was extracted with equal volume of phenolchloroform, aqueous phase removed to a new tube.
- DNA was precipitated using ethanol precipitation. (see Other Protocols)
- DNA was dissolved in 1.5 mL nuclease free water
II. PCR Amplification of BAA-1870, BAA-1875, and WT TcdC
Protocol
- Primers were diluted to 10 uM
- dNTP was diluted to 10 mM
- DNA samples were diluted to 125 ng/uL
- The following master mix solution was prepared
- 2 uL of DNA was added to 48 uL of the master mix
- PCR reaction was run in a thermocycler using the following conditions for 35 cycles:
- The PCR reactions were run on a 1% agarose gel and purified using gel extraction (see Other Protocols)
Reagent | 1x(uL) |
---|---|
Forward Primer | 2.5 |
Reverse Primer | 2.5 |
dNTP | 1 |
Phusion Buffer | 10 |
Phusion High Fidelity Polymerase | 0.5 |
Nuclease-free water | 31.5 |
Step | Temperature (C) | Time |
---|---|---|
Initial Denaturing | 98 | 10 minutes |
Denaturing | 98 | 30 seconds |
Annealing | 50 | 20 seconds |
Elongation | 72 | 20 seconds |
Final elongation | 72 | 10 minutes |
Hold | 4 | Indefinite |
Digestion of TcdC and pET15b
Protocol
- The following reaction was set up:
- Reactions were incubated at 37 degrees Celsius for one hour
- Digestion reaction were run on a 1% agarose gel and purified using gel extraction (see Other Protocols)
Component | 50 uL Reaction |
---|---|
DNA | 1 ug |
FastDigest Buffer | 5 uL |
Ndel | 1.0 uL |
BamHI | 1.0 uL |
Nuclease free water | To 50 uL |
Ligation of TcdC to pET15b
Protocol
- The following reaction was set up:
- The ligation reactions were incubated at 16 degrees Celsius overnight.
Component | 20 uL Reaction |
---|---|
10X T4 Ligase Buffer | 2 uL |
Vector DNA | 70.54 ng (0.02 pmol) |
Insert DNA | 25.81 ng (0.06 pmol) |
T4 DNA Ligase | 1 uL |
Nuclease-free water | To 20 uL |
V. Transformation Using Chemically Competent Cells
Protocol
- Invitrogen DH5 alpha cells were thawed on ice for 10 minutes, 50 uL of cells were pipetted into transformation tube
- 5 uL of ligation reaction was added into cell mixture
- Mixture was incubated on ice for 30 minutes
- Mixture was heat shocked at 42 C for 30 seconds
- Mixture was transferred to ice for 5 minutes.
- 950 uL of LB broth was added to mixture
- Mixture was incubated at 37 C for 60 minutes, shaking at 250 rpm
- Selection plates containing 50 ug/mL of ampicillin were warmed to 37 C
- Cells were pelleted at 4000 g for 1 minute
- 900 uL of LB broth was removed
- Cells were plated onto selection plates and incubated for 16 hours at 37 C
- Colonies were picked and grown in 5 mL of LB broth for 16-18 hours
VI. Miniprep Plasmids
Promega Miniprep Kit was used.
- 1.5 mL of liquid culture was centrifuged at maximum speed for 30 seconds. Supernatant was discarded
- An additional 1.5 mL of bacterial culture was added to the same tube and step 1 was repeated.
- 600 uL of nuclease-free water was used to resuspend the cells
- 100 uL of cell lysis buffer was added and mixed by inverting the tube 6 times
- 350 uL of cold neutralization solution was added
- Mixture was centrifuged at maximum speed for 3 minutes
- Supernatant (~900 uL) was transferred to a minicolumn without disturbing the cell debris pellet and centrifuged at maximum
- speed for 15 seconds. Supernatant was discarded.
- 200 uL of endotoxin removal wash was added to the minicolumn. Minicolumn was centrifuged at maximum speed for 15 seconds
- 400 uL of column wash solution was added to the minicolumn and centrifuged for 30 seconds
- Minicolumn was transferred to a clean 1.5 mL Eppendorf tube and 30 uL of elution buffer was added
- After 1 minute, tubes were centrifuged for 15 seconds to elute the plasmid DNA.
Other Protocols
Ethanol Precipitation
- Add 0.1 volumes of 3M NaOAc, 2.5 volumes of ice cold 100% ethanol, and mix
- Precipitate at -20 C for at least one hour
- Centrifuge at 15000 rpm at 4 C for 30 minutes
- Wash pellet twice with 0.5 mL of ice cold 75% ethanol, spinning at 4 C for 10 minutes each time
- Remove ethanol and dry the pellet in a Speed-Vac
- Resuspend pellet in nuclease free water
Agarose Gel Electrophoresis
- Dilute 50X TAE to 1X
- Add 1% mass of agarose to TAE
- Microwave until agarose has dissolved
- Cool to around 50 C, then add SYBR Safe (1 uL for every 10 mL of TAE)
- Pour gel into casting tray with a comb
- Once gel has solidified, place the gel into a gel electrophoresis machine and add 1X TAE until the gel is fully covered
- Load 5 uL of 1kb DNA ladder into the first well and DNA samples into subsequent wells
- Run the gel for about 45 minutes
DNA Extraction from Agarose Gels
Nucleospin Gel and PCR Clean-up Kit was used
- Use a clean razor blade to excise DNA fragment from gel
- For every 100 mg of gel, add 200 uL of Buffer NTI (gel solubilization solution)
- Place a binding column into a collection tube and add 700 uL of sample. Centrifuge for 30 seconds at 11,000 g. Discard flow through. Repeat if necessary
- Add 700 uL of Buffer NT3 (wash buffer). Centrifuge for 30 seconds at 11,000 g. Discard flow-through. Repeat this step to minimize chaotropic salt carry-over.
- Centrifuge for 1 minute at 11,000 g to remove Buffer NT3 completely. To remove residual ethanol, incubate the columns for 5 minutes at 70 C prior to elution
- Place the column into a new 1.5 mL Eppendorf tube and add 30 uL of nuclease-free water. Incubate for 1 minute before centrifuging for 1 minute at 11,000 g.