XX03CAB39LA (3ZHP) Materials & Methods |
Sequence - STK24A |
Entry Clone Source: Synthetic DNA |
SGC Construct ID: STK24A-c010 |
Vector: pNIC28-Bsa4. Details [PDF ]; Sequence [ FASTA ] or [ GenBank ] |
DNA sequence: |
Final protein sequence (Tag sequence in lowercase): |
Tags and additions: Cleavable N-terminal His6 tag |
Host: BL21(DE3)-R3-pRARE2. |
Growth Medium & Induction Protocol: A number of colonies were used to inoculate 50 ml of LB media containing 50 µg/ml kanamycin and 34 µg/ml chloramphenicol in a 250 ml baffled shaker flask, which was placed in a 37°C shaker overnight. The next day 3x 10 ml of this starter culture was used to inoculate 3x 1L of LB media containing 40 µg/ml kanamycin in 2L baffled shaker flasks. When the OD600 was approximately 0.4-0.5, the temperature was reduced to 20°C. When the OD600 was 0.6 the cells were induced by the addition of 0.5 mM IPTG. The expression was continued overnight. |
Lysis buffer: 50 mM Hepes pH 7.4, 500 mM NaCl, 5% Glycerol, 20mM Imidazole, +0.5 mM TCEP, +0.2 mM PMSF |
Sequence - CAB39LA |
Construct Source: Dario Alessi |
Final protein sequence (Tag sequence in lowercase): |
Tags and additions: N-terminal, Prescission protease cleavable glutathione S-transferase tag. |
Host: BL21(DE3)-R3-pRARE2. |
Growth Medium & Induction Protocol: The construct DNA was transformed into homemade chemically competent cells of the expression strain by a standard heat shock procedure. A number of colonies were used to inoculate 50 ml of LB media containing 50 µg/ml ampicillin and 34 µg/ml chloramphenicol in a 250 ml baffled shaker flask, which was placed in a 37°C shaker overnight. The next day 3x 10 ml of this starter culture was used to inoculate 3x 1L of LB media containing 80 µg/ml ampicillin in 2L baffled shaker flasks. When the OD600 was approximately 0.4-0.5, the temperature was reduced to 20°C. When the OD600 was 0.6 the cells were induced by the addition of 0.5 mM IPTG. The expression was continued overnight. Cells were spun at 5000rpm for 10 mins and the pellets resuspended in Lysis Buffer and then frozen at -20°C. |
Lysis buffer: 50mM Tris-HCl pH 8.0; 1mM EDTA; 1mM EGTA; 1mM sodium orthovanadate; 25mM NaF; 5mM DTT; 1:2000 Protease Inhibitor Cocktail. |
Purification - STK24A |
Cell Lysis: The resuspended cell pellet was thawed and lysed by sonication. PEI (polyethyleneimine) was added to a final concentration of 0.15 %. The cell debris and precipitated DNA were spun down. |
Column 1: 5 ml of Ni-Sepharose in a 2 cm diameter gravity flow column |
Column 1 Buffers: |
Column 1 Procedure: The clarified supernatant was passed through the column. The column was washed with 50 ml of Binding Buffer and 50 ml each of Wash Buffer 1 and 2. 25 ml of Elution Buffer was passed through to elute the protein. |
Column 2: S200 16/60 Gel Filtration (GE Healthcare) |
Column 2 Buffer: |
Column 2 Procedure: The STK24A protein was concentrated to 5 ml volume and injected onto the gel filtration column |
Purification - CAB39LA |
Cell Lysis: The resuspended cell pellet was thawed and lysed by sonication. PEI (polyethyleneimine) was added to a final concentration of 0.15 %. The cell debris and precipitated DNA were spun down. |
Column 1: 5 ml of Glutatione-Sepharose in a 2 cm diameter gravity flow column. |
Column 1 Buffers: |
Column 1 Procedure: The clarified supernatant was passed through the column. The column was washed six times with 10 ml of Buffer 1, then six times with 10 ml of Buffer 2. The N-terminal GST tag was removed by incubating the beads with PreScission protease (40mg protease per 1ml of beads) at room temperature for 30 min and subsequently at 4°C for 16 hours. The protein was eluted with 50 ml of Buffer 2. |
Gel Filtration Purification - STK24A:CAB39LA complex |
Column 3: S200 16/60 Gel Filtration (GE Healthcare) |
Column 3 Buffers: |
Column 3 Procedure: The CAB39LA protein was concentrated to 7.8 mg/ml. The STK24A protein was concentrated to 2.4 mg/ml. Equimolar amounts of each protein were mixed and injected onto the gel filtration column. |
Concentration: The protein complex was concentrated to 9.7 mg/ml (measured by 280 nm absorbance). |
Mass spec characterization: |
Crystallization: Crystals grew from a 1:1 ratio of protein and precipitant solution (0.2M Na/KPO4, 10% PEG 3350, 10% Ethylene Glycol), using the vapour diffusion method. |
Data Collection: |