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zhang8826857(½ð±Ò+15): ^_^^_^^_^ 2011-12-06 11:29:19 zhang8826857: »ØÌûÖö¥ 2011-12-06 11:42:58
Transposon-mediated Mutagenesis
Step 1 - Amplify ORF from MG1655
1.0 ul genomic DNA (30ng/ul)
5.0 ul gene specific primer mix
4.0 ul 2.5 mM dNTP
5.0 ul 10x Turbo Pfu buffer
0.7 ul Turbo Pfu
34.3 ul sterile distilled H2O
50 ul
95¡ãC 95¡ãC 55¡ãC 72¡ãC 72¡ãC 4¡ãC
1min 15sec 15sec 4min 5min forever
25 cycles
Step 2 - Transposition reaction
6 ul ORF PCR product (~100-200ng)
2 ul Tn (Transposon, 200ng = 0.2pM)
1 ul 10x Tn reaction buffer (Epicentre)
1 ul Tnase (Transposase; Epicentre)
10 ul
Vortex, spin down
37¡ãC for 2hr
Add 1 ul stop solution, 10min 70¡ãC
Purify by passing through G50 column
Step 3 ¨C Transformation
MG1655 cells harboring the pKD46 plasmid (Datsenko and Wanner, 2000, PNAS 97(12):6640-5) are induced with arabinose to activate expression of the lRed genes and prepared for electroporation.
1. Mix following on ice:
4.4 ul transposition reaction
40 ul MG1655 w/pKD46 electrocompetent cells
2. Transfer entire volume (~45ul) to chilled cubette (0.1cm gap), kept on ice
3. Electroporate with the following settings (for BioRad Pulse Controller)
Low Range 200
High Range 500
Capacitance (uF): -25
Total Volts: 1.8kV
4. Resuspend cells with 1ml LB and transfer contents to a 48-well growth block
5. Outgrow at 37¡ãC for 1hr
6. Spread entire outgrowth on a corresponding labeled LB + Amp(100ug/ml)/Kan (50ug/ml) plate in a hood and air dry.
7. Grow at 300 (to maintain pKD46). (1- 2 days)
Step 4- Picking
Day 1
1. Streak 2 colonies to single colonies on LB + Amp(100ug/ml)/Kan (50ug/ml) plates. These will be the first colonies to verify.
2. Pick 3 additional colonies into separate 96-well flat bottom plates containing 200ul Freezing media + Amp(100ug/ml)/Kan(50ug/ml) maintaining original well location.
3. Grow 300 overnight.
Day 2:
1. Grow 1 colony from each streak plate in a 96-well block with each well containing 1ml Freezing media + Amp(100mg/ml)/Kan(50mg/ml). Grow 300 overnight.
2. Freeze overnights of the other 3 plates.
Step 5¨C Verify mutation by Culture PCR
1. Prepare sample
Mix culture thoroughly.
Transfer 20ul of culture into a 96-well plate and dilute with 80ul H2O Mix thoroughly
2. PCR Reaction.
5 ul diluted culture
4 ul gene specific primer mix (same as in Step 1)
2.5 ul ExTaq premix
16 ul H2O
50 ul
95¡ãC 94¡ãC 55¡ãC 72¡ãC 72¡ãC 4¡ãC
5min 30sec 15 sec 4min 5min forever
30cycles
3. Run 7 ul on 1 % test gel in 0.5x TAE to check.
4. Analyze gel results; mutants will be ~1.2kb larger than original gene length.
Step 6 - Confirm mutations by sequencing
1. EXOSAP clean up
- Transfer 10ul of PCR product for all genes with mutant sized fragments into a separate PCR plate
- Add 4ul ExoSAP-IT (USB) to each reaction
- Spin briefly
- React @ 37¡ãC for 30min, then 15min@ 80¡ãC
2. Sequence
1. Add a mix of the following to each ExoSAP reaction:
1ul of primer (KAN-2 FP-1 @ 10uM -Epicentre)
2ul Big Dye dilution Buffer (Promega)
3ul Big Dye
2. Reaction conditions: (10sec@96C; 5sec@50C; 4min@60C) for 25cycles.
3. Purify through a G50 column
4. Dry plate and run on sequencer
3. Make tube stocks of confirmed mutants
Step 7 - Curing the temperature sensitive pKD46 plasmid
1. Streak confirmed mutants on a LB + Kan plate (from the above stock). Grow at 43¡ã overnight (non-permissive temperature for pKD46 replication).
2. With a single colony inoculate the following:
1. Growth block well containing 1ml Freezing media + Kan(50ug/ml)/well .
2. LB+Kan agar in a 96 well plate
3. LB+Amp agar in a second 96-well plate
3. Grow overnight at 37¡ãC. Cured cells will grow on Kan but not on Amp.
4. Confirm by PCR and sequencing as above. |
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