Editing S30 E. coli extract (section)

== Protocol 3 ==

[http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0165137 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0165137]<br/>Preparation of S30-T7 lysate

1.1. Streak the bacteria (transformed with pAR1219) on an LB-agar plate.

AR1219: expressing T7 RNA Polymerase&nbsp;&nbsp;[https://www.sigmaaldrich.com/catalog/product/sigma/t2076?lang=en&region=US https://www.sigmaaldrich.com/catalog/product/sigma/t2076?lang=en&region=US]

1780:&nbsp;pT7A3-T7-RNAPol-Y639F, 0.5 mM IPTG

1080 pBad24-T7-RNAPol:&nbsp;0.2% arabinose

1.2. Use a single colony to inoculate 10 ml LB media in 100 mL flask, and grow it overnight at 37°C with shaking at 250 rpm on a floor incubator shaker. This step will obtain a starter solution (duplicate).

1.3. Inoculate each one of the 500 ml TB media inside a 2 liters flask using the 10 ml starters.

1.4. Grow the culture at 37°C until it reaches OD600, ~= 1, by monitoring the culture's OD at 600 nm using a spectrophotometer. Once the required OD is achieved, add 0.4 mM IPTG.

1.5. Grow the culture at 37°C until it reaches OD600, ~= 4.

1.6. Centrifuge at 7,000 x g for 10 min at 4°C.

1.7. Re-suspend each pellet in 500 ml of S30 lysate buffer, and centrifuge at 7,000 x g for 10 min at 4°C.

S30 lysate buffer:10 mM Tris-Acetate, pH 7.4, 10 mM Magnesium acetate, 60 mM potassium acetate, 1 mM DTT

'''1 L of 100x stock'''

1M Tris-Acetate pH 7.2, 121.14 g Trizma Base (Sigma T6066) Adjust pH to 7.2 with Glacial Acetic Acid

1.4 M Mg(Acetate)2,&nbsp; 300.16 g Mg(OAc)2 Tetrahydrate (Sigma 228648)

6.0 M K(Acetate),&nbsp; 588.90 g K(OAc) (Mallinckrodt 6700)

'''10X S30 buffer:'''

100 mM Tris acetate, pH 8.2

160 mM potassium acetate

140 mM magnesium acetate

pH 8.3 with potassium hydroxide

'''&nbsp;S30 buffer A''': 1X S30 buffer containing 0.5 mM PMSF, 1 mM DTT and 7.2 mM -mercaptoethanol

1.8. Resuspend in 15 ml of S30 lysate buffer.

1.9. Break the cells by one pass through a high pressure homogenizer at a working pressure of 15,000 psi, with an air pressure of 4 bar.

1.10. Add 100 pL of 0.1 M DTT to each 10 ml of homogenized suspension.

1.11. Centrifuged the suspension at 24,700 x g or 13,000 x g for 30 min at 4°C.

1.12. Divide the supernatant into aliquots of 200 pL into 1.5 ml tubes.

1.13. Freeze the tubes immediately by liquid nitrogen and store at -80°C for further use.&nbsp;

A single colony was used to inoculate fresh LB media, and was grown overnight at 37°C with orbital shaking of 250 rpm. This was used as a starter to inoculate fresh Terrific Broth (TB) the following day at a 1:50 starter:medium ratio. The media were sterilized and supplemented with ampicillin at 50 μg/ml. The culture was grown at 37°C to OD&lt;/span&gt;<span style="box-sizing: border-box; vertical-align: 0px; position: relative; top: 0.5ex; font-family: arial;">600</span><span style="font-family: arial;">≈1, upon which 0.4 mM 0.2 μm filtered Isopropyl β-D-1-thiogalactopyranoside (IPTG) solution was added. The culture was further grown at 37°C until it reached OD</span><span style="box-sizing: border-box; vertical-align: 0px; position: relative; top: 0.5ex; font-family: arial;">600</span><span style="font-family: arial;">≈4 and was centrifuged at 7,000 x g for 10 min at 4°C. The pellet was re-suspended in the same volume (1:1 v/v) of cold S30 lysate buffer containing: 10mM Tris-acetate at pH = 7.4, 14mM magnesium acetate, 60 mM potassium acetate, 1 mM 0.2 μm filtered dithiothreitol (DTT) and 0.5 ml/L 2-mercaptoethanol. Subsequently, the suspension was centrifuged again and was resuspended in 15 ml of S30 lysate buffer. Then, the cells were broken by one pass through an emulsiFlex-C3 high pressure homogenizer (Avestin, Mannheim, Germany) that was pre-cooled to 4°C and at a working pressure of 15,000 psi, with an air pressure of 4 bar. One-hundred μl of 0.1 M DTT was added to each 10 ml of homogenized suspension. Finally, the suspension was centrifuged at 24,700 x g or 13,000 x g for 30 min at 4°C divided into aliquots of 200 μl, frozen by liquid nitrogen and stored at -80°C for further use.</span>

<br/><span style="font-family: arial;">A detailed protocol for the preparation of the S30-T7 lysate is described in Table 1. Briefly, S30-T7 lysates were prepared from E. coli BL21(DE3) and MRE600 transformed with TargeTron® vector pAR1219 (Sigma-Aldrich, Rehovot, Israel). Bacteria glycerol stocks were streaked on an agar Luria Bertani (LB) plate. A single colony was used to inoculate fresh LB media, and was grown overnight at 37°C with orbital shaking of 250 rpm. This was used as a starter to inoculate fresh Terrific Broth (TB) the following day at a 1:50 starter:medium ratio. The media were sterilized and supplemented with ampicillin at 50 μg/ml. The culture was grown at 37°C to OD600≈1, upon which 0.4 mM 0.2 μm filtered Isopropyl β-D-1-thiogalactopyranoside (IPTG) solution was added. The culture was further grown at 37°C until it reached OD600≈4 and was centrifuged at 7,000 x g for 10 min at 4°C. The pellet was re-suspended in the same volume (1:1 v/v) of cold S30 lysate buffer containing: 10mM Tris-acetate at pH = 7.4, 14mM magnesium acetate, 60 mM potassium acetate, 1 mM 0.2 μm filtered dithiothreitol (DTT) and 0.5 ml/L 2-mercaptoethanol. Subsequently, the suspension was centrifuged again and was resuspended in 15 ml of S30 lysate buffer. Then, the cells were broken by one pass through an emulsiFlex-C3 high pressure homogenizer (Avestin, Mannheim, Germany) that was pre-cooled to 4°C and at a working pressure of 15,000 psi, with an air pressure of 4 bar. One-hundred μl of 0.1 M DTT was added to each 10 ml of homogenized suspension. Finally, the suspension was centrifuged at 24,700 x g or 13,000 x g for 30 min at 4°C divided into aliquots of 200 μl, frozen by liquid nitrogen and stored at -80°C for further use.</span>



{|
|-
| <span style="font-family: arial;">Cell-free reaction component</span>
| <span style="font-family: arial;">Final concentration in solution&nbsp;</span>
|-
| <span style="font-family: arial;">HEPES-KOH (pH = 8)</span>
| <span style="font-family: arial;">55 mM&nbsp;</span>
|-
| <span style="font-family: arial;">Magnesium acetate</span>
| <span style="font-family: arial;">14 mM&nbsp;</span>
|-
| <span style="font-family: arial;">Potassium acetate</span>
| <span style="font-family: arial;">50 mM&nbsp;</span>
|-
| <span style="font-family: arial;">Ammonium acetate</span>
| <span style="font-family: arial;">155 mM&nbsp;</span>
|-
| <span style="font-family: arial;">Polyethylene glycol (PEG)</span>
| <span style="font-family: arial;">3% (v/v)&nbsp;</span>
|-
| <span style="font-family: arial;">3-phosphoglycerate (3-PGA)</span>
| <span style="font-family: arial;">40 mM&nbsp;</span>
|-
| <span style="font-family: arial;">20 amino acids</span>
| <span style="font-family: arial;">2.5 mM&nbsp;</span>
|-
| <span style="font-family: arial;">Adenine triphosphate (ATP)</span>
| <span style="font-family: arial;">1.2 mM&nbsp;</span>
|-
| <span style="font-family: arial;">Guanidine triphosphate (GTP)</span>
| <span style="font-family: arial;">1 mM&nbsp;</span>
|-
| <span style="font-family: arial;">Uridine triphosphate (UTP)</span>
| <span style="font-family: arial;">0.8 mM&nbsp;</span>
|-
| <span style="font-family: arial;">S30-T7 lysate</span>
| <span style="font-family: arial;">30% (v/v)&nbsp;</span>
|-
| <span style="font-family: arial;">DNA template</span>
| <span style="font-family: arial;">10 pg/mL&nbsp;</span>
|-
| colspan="2" | <span style="font-family: arial;">DNase, RNase free H2O to reaction volume&nbsp;</span>
|}



<span style="font-family: arial;">A. Materials and solutions required:&nbsp;</span>

<span style="font-family: arial;">1M HEPES-KOH (pH = 8)</span>

<span style="font-family: arial;">1M magnesium acetate</span>

<span style="font-family: arial;">1M potassium acetate</span>

<span style="font-family: arial;">5.2 M ammonium acetate</span>

<span style="font-family: arial;">50% (v/v) Polyethylene glycol 6000 (PEG)</span>

<span style="font-family: arial;">0.5 M 3-phosphoglycerate (3-PGA)</span>

<span style="font-family: arial;">Notes:&nbsp;</span>

<span style="font-family: arial;">50 mM of 17 amino acids These 17 amino acids are alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, proline, serine, threonine, and valine. 50 mM of 3 amino acids These 3 amino acids are tryptophan, phenylalanine, and tyrosine.</span>

<span style="font-family: arial;">100 mM Adenine triphosphate (ATP)</span>

<span style="font-family: arial;">50 mM Guanidine triphosphate (GTP)</span>

<span style="font-family: arial;">100 mM Uridine triphosphate (UTP)</span>

<span style="font-family: arial;">S30-T7 lysate Prepared according to Table 1</span>

<span style="font-family: arial;">DNase, RNase free H2O B. Equipment:</span>

<span style="font-family: arial;">Notes: Floor incubator shaker or a Thermomixer® C. Procedure:&nbsp;</span>