Team:Heidelberg/Sandbox


Short introduction

“The sea is everything. […] The sea is the vast reservoir of Nature. The globe began with sea, so to speak”, Nemo said while the “Nautilus” was cruising with a school of hammerhead sharks deep beneath the waves.

And the captain was right. Deep in the ocean billions of years ago the miracle of nature took place as a pool of small molecules evolved to self-replicating lifeforms. The flagship role in this development was probably taken by the most versatile class of molecules in the history of life: RNA.

Seemingly random nucleotides happened to be in the right order to form the first biocatalysts that made life on the blue planet possible. Today we know those miracles of nature as ribozymes. Inspired by this, humanity took evolution into their own hands to create aptamers – nucleic acids capable of encaging molecules. This allows for the detection of virtually anything. Still this process has been tedious and time consuming much like fishing with a rod in an ocean. We want to revolutionize this former evolutionary process and want to make it swift like a shark tracking down its prey.

Yet to really bring out the strengths of these simple yet powerful molecules just comprised of A, U, C and G we want to combine aptamers and ribozymes to create a toolset for the synthetic biologist to create allosteric ribozymes able to sense a variety of molecules. Therefore, we hope to introduce the true origins of life and the capabilities of functional RNA to iGEM.

Join us as we sail forth into new waters of synthetic biology.

Further content

Test
Test
Notebook

Supporting iGEM Team Paris Bettencourt

iGEM Paris Bettencourt has set up a visual databse that should help various iGEM teams collaborate and find common ground. In that database all teams can enter techniques, keywords, organism and many more thev are knowdledgeable in or have been working on. As common dots are connected automatically, it's easy so see, whom to ask for a collaboration.
Though we came a little late to the party, we really loved the idea and hoped, that the database has helped various teams!

"Rhizi is an open-sourced web of knowledge where nodes are sources of information (e.g. scientific articles, questions, blog posts) and edges are the links between them. The goal of Rhizi is to create information rich links between knowledge, open questions and ideas, through encouraging users to vote, comment, and create new relationships."

Collecting impressions from the community

It’s done. We’ve finally decided upon a logo. It’s beautiful, it’s blue, it’s fishy *wink*. The next step was to choose a color scheme and a general style for the wiki. As we feared that our own ideas might be too similar we thought of asking a broader public how they would design a website based on our logo. In order to do so, we headed to the ’Neckarwiese’. During summer, a big part of Heidelbergs population decideds to go there and enjoy the sun, have a BBQ or just relax – so we caught them off guard.

We have had prepared a little presentatio with which we introduced them to iGEM and Synthetic Biology. Afterwards we explained them what we planned on doing, showed them our logo and asked, how they would design a website, based on what they’ve just heard. The general consens was to go for a blue theme, maybe add a little algae green and generally stick to maritime iconography. Unexpectedly we actually met someone who knew his stuff: Natalie, a student of the history of arts from Berlin. She gave us useful advice on how play with the different colors, what to avoid and even added a little touch of history to it. Lucky catch!

With fresh ideas we headed back to the lab and continued our experiments, being envious of all the people that could continue to sleep in the sun.

We’ve been lucky and actually met someone knowledgable in arts. Her name is Nati and she studies the history of art in Berlin.

Panel Discussion

Synthetic biology - engineering life with its most fundamental units by using DNA BioBricks and other modularly combinable parts, has a potential beyond scope and can improve the quality of life for everyone and mankind as a whole. The ultimate goal of researchers in synthetic biology is not only the understanding of life itself and how it functions, but applying the acquired knowledge to make a change within their community.

To investigate the current state of the research and its acceptance in society, we talked to scientists and asked them how their work has influenced their community. Nonetheless, it is of absolute necessity to include the entire society. We decided to do this by organizing a panel discussion evening dedicated to the topic 'Synthetic biology - Bricks for a healthy life?', i.e. synthetic biology in medicine.

As research in general and especially synthetic biology relies on a community, on interaction between researchers and the exchange of ideas and expertise, we asked experts and researchers from different fields to join us for this evening and we distributed flyers and placards to invite the broad society. However, we wanted to go a step further: The panel discussion was not limited to the audience in Heidelberg, it was simultaneously translated from German to English and broadcasted it via a live stream.

Despite the great enhancements synthetic biology can achieve, engineering with building blocks that are so close to the basic principles of life itself comes with a range of ethical questions and security precautions to consider. We see it as our immanent responsibility as iGEM team to address these questions and to take concerns very seriously. Hence, we invited Prof. Dr. Axel Bauer, who has been member of the German ethics council for several years and Dr. Joachim Boldt who works as assessor for the German ethics commitee for ethical implications of synthetic biology. Both of them are highly involved in the field of medical ethics also due to being professor for this subject. In order to review the safety concerns, we were very glad to have Dr. Harald König, who works at the Institute for Technology Assessment and System Analysis, as our guest.

Different experts were invited to an interdisciplinary talk evening

Politics and law play a very big role when discussing the application of synthetic biology in real life. Researchers need to obey the juridical boundaries and on the contrary the legislature has to react to novel developments and find a compromise between many different opinions, some being more conservative, others more progressive. To reflect this interweaving, we additionally invited local politicians, such as Prof. Dr. Nicole Marmé who is member of the city council of Heidelberg. Dr. Stephan Brandt, chairman of the department for Biotechnological Innovation, Nanotechnology and Genetic Engineering, investigates how laws need to be adapted to the most recent findings in synthetic biology and genetics and we are very glad he joined us for this evening. Finally, the topic that stands in the center of this evening is, after all, research in synthetic biology. For that reason, we asked Dr. Dirk Grimm, who works on the CRISPR-Cas system and who knows the cutting edge developments to be the scientific representative in the panel.

Jasmin and Max gave a great introduction to synthetic biology in medicine

After a lot of planning, organization and set up of all the required technical equipment (thanks again to Dr. Jens Wagner from the Physics Department), the discussion evening could start with a brief introduction to the topic given by Jasmin and Max from our team. As we wanted the main part of the evening to be an open discussion, we deliberately made the introduction very compact. For the remaining 1.5 hours of the evening, Tim navigated our guests, as well as the audience through the discussion.

The involvement of the audience was amazing, proving that this topic is indeed highly interesting to a large part of the society. Most eminently, we were very happy that additional to the approximately 100 guests that joined us physically in our institute, we had almost 400 viewers online, among them also other iGEM teams, such as iGEM Team Cambrige (link). Besides watching, our followers on twitter were also very engaged in asking questions that were then addressed by Tim and the invited experts.

Luckily, many people came to our talk evening. Even more joined us online via our simultaneously translated live stream and asked questions with #askigemheidelberg

The topics discussed ranged from green to red biotechnology and were contemplated in a highly interdisciplinary way (with the focus on medical applications nonetheless). Besides, and in correspondence to the initialization of the “Community lab” track in iGEM, we addressed biohacking and the implications of it on society, the scientific community and the communication between the two entities. Question were asked about ethical problems and implications of in vivo and in vitro technologies, but also about dreams and wishes of the scientists regarding future developments in this field. The question iGEM team Cambridge nicely summarizes the last part of the discussion: “How can synthetic biologists better communicate their research to the public?” This includes the role of politicians and law makers, as well as the responsibility of everyone who is involved in research to put a focus on the outreach and the interaction, not only with the scientific community, but also with the broader public.

So far, many iGEM teams have organized discussion evenings and invited people from the broad society to join an interdisciplinary evening. This approach is great and helps a lot to improve the communication between scientists and the public. Nonetheless, there are still barriers to overcome:

  • The interested population of one city is not representing the entire society. Hence, we decided to provide the opportunity to join us online via live stream. This should not be limited to watching the discussion passively, that is why everyone could ask questions via twitter by #askigemheidelberg. These questions were then shown in the discussion, so that our invited guests could reply or reflect on them.
  • The lingua franca in research is English, however not everybody is capable of speaking English fluently. Therefore, we deliberately chose German as the language the discussion was held in. This way, everyone who was interested had the possibility to follow. In order to keep the event international and also understandable for those who watched online, we translated the event simultaneously to English.

week number 38

▼2015-09-14 Test bitte löschen

10 x <i>in vitro</i> transcription buffer

50 mM Tris ph 7.5, 100 mM NaCl, 20 mM MgCl<sub>2</sub>, 0,01 % SDS
 

week number 37

▼2015-09-10 DNAzyme Activity: DNAzyme with ATP aptamer and calculated Kanamycin aptamer

Samples:

  • 10-23 DNAzyme: xxfs032xx
  • 7-18 DNAzyme: xxfs033xx
  • 10-23 DNAzyme with ATP aptamer with linker: xxfs019xx
  • 7-18 DNAzyme with ATP aptamer with linker: xxfs027xx
  • 10-23 DNAzyme with ATP aptamer A: xxfs017xx, B: xxfs018xx
  • 7-18 DNAzyme with ATP aptamer A: xxfs025, B: xxfs026xx
  • 10-23 DNAzyme with calculated Kan aptamer: xxfs034xx
  • 7-18 DNAzyme with calculated Kan aptamer candidate I: xxfs035xx
  • 7-18 DNAzyme with calculated Kan aptamer candidate II: xxfs036xx
  • 7-18 DNAzyme with calculated Kan aptamer candidate III: xxfs037xx

Stock solutions and conditions:

 

cStock

cFinal

Tris HCl ph 7.5

1 M

50 mM

DNAzyme (A)

10 µM

500 nM

DNAzyme B

10 µM

500 nM

Substrate

1 µM

200 nM

NaCl

1 M

100 mM

MgCl2

1 M

20 mM

SDS

20 %

0,01 %

Adenosine in H2O:DMSO 1:2

33 mM

5 mM

H2O

 

ad 25 µL

 

Pipetting scheme:

#

 

 

Tris HCl ph 7.5

DNAzyme A

DNAzyme B

Substrate

NaCl

MgCl2

SDS

Adenosine

H2O

Final

1

FS032

10-23D

1,25

1,25

0,00

5,00

2,50

0,50

1,25

3,75

9,50

25,00

2

FS033

7-18D

1,25

1,25

0,00

5,00

2,50

0,50

1,25

3,75

9,50

25,00

3

FS019

10-23DmLink

1,25

1,25

0,00

5,00

2,50

0,50

1,25

3,75

9,50

25,00

4

FS027

7-18DmLink

1,25

1,25

0,00

5,00

2,50

0,50

1,25

3,75

9,50

25,00

5

FS017+18

10-23D_A+B

1,25

1,25

6,25

5,00

2,50

0,50

1,25

3,75

3,25

25,00

6

FS025+26

7-18D_A+B

1,25

1,25

6,25

5,00

2,50

0,50

1,25

3,75

3,25

25,00

7

FS032

10-23D

1,25

1,25

0,00

5,00

2,50

0,50

1,25

0,00

13,25

25,00

8

FS033

7-18D

1,25

1,25

0,00

5,00

2,50

0,50

1,25

0,00

13,25

25,00

9

FS019

10-23DmLink

1,25

1,25

0,00

5,00

2,50

0,50

1,25

0,00

13,25

25,00

10

FS027

7-18DmLink

1,25

1,25

0,00

5,00

2,50

0,50

1,25

0,00

13,25

25,00

11

FS017+18

10-23D_A+B

1,25

1,25

6,25

5,00

2,50

0,50

1,25

0,00

7,00

25,00

12

FS025+26

7-18D_A+B

1,25

1,25

6,25

5,00

2,50

0,50

1,25

0,00

7,00

25,00

13

FS032

-10-23D

1,25

1,25

0

0

2,5

0,5

1,25

0

18,25

25,00

14

FS033

-7-18D

1,25

1,25

0

0

2,5

0,5

1,25

0

18,25

25,00

15

FS019

-10-23DmLink

1,25

1,25

0

0

2,5

0,5

1,25

0

18,25

25,00

16

FS027

-7-18DmLink

1,25

1,25

0

0

2,5

0,5

1,25

0

18,25

25,00

17

FS017+18

-10-23D_A+B

1,25

1,25

6,25

0

2,5

0,5

1,25

0

12

25,00

18

FS025+26

-7-18D_A+B

1,25

1,25

6,25

0

2,5

0,5

1,25

0

12

25,00

19

Adenosine

Substrate only

1,25

0

0

5

2,5

0,5

1,25

3,75

10,75

25,00

 

 

#

   

Tris HCl ph 7.5

DNAzyme A

DNAzyme B

Substrate

NaCl

MgCl2

SDS

Kan

H2O

Final

20

FS032

10-23D

1,25

1,25

0

5

2,5

0,5

1,25

1,25

12

25

21

FS033

7-18D

1,25

1,25

0

5

2,5

0,5

1,25

1,25

12

25

22

FS034

Kan

1,25

1,25

0

5

2,5

0,5

1,25

1,25

12

25

23

FS035

Kan I

1,25

1,25

0

5

2,5

0,5

1,25

1,25

12

25

24

FS036

Kan II

1,25

1,25

0

5

2,5

0,5

1,25

1,25

12

25

25

FS037

Kan III

1,25

1,25

0

5

2,5

0,5

1,25

1,25

12

25

26

FS032

10-23D

1,25

1,25

0

5

2,5

0,5

1,25

0

13,25

25

27

FS033

7-18D

1,25

1,25

0

5

2,5

0,5

1,25

0

13,25

25

28

FS034

Kan

1,25

1,25

0

5

2,5

0,5

1,25

0

13,25

25

29

FS035

Kan I

1,25

1,25

0

5

2,5

0,5

1,25

0

13,25

25

30

FS036

Kan II

1,25

1,25

0

5

2,5

0,5

1,25

0

13,25

25

31

FS037

Kan III

1,25

1,25

0

5

2,5

0,5

1,25

0

13,25

25

32

Kan

Substrate only

1,25

0

0

5

2,5

0,5

1,25

1,25

13,25

25,00

33

 

Substrate only

1,25

0

0

5

2,5

0,5

1,25

0

14,5

25,00

 

Results and Outlook:

Positive controls worked, Adenosine dependency could be detected for one candidate.

▼2015-09-10 Click reaction of Label-, Label AU RNA [1, 2, 3]

For 51.5µL

Cstock

Cfinal

V[µL]

Phosphate Buffer - pH 7, 0.1M

100mM

50mM

25

Alexa 488 azide

10µM

400nM

2

RNA

1µM

200nM

10

CuSO4

20mM

1mM

2.5

THPTA

50mM

5mM

5

NaAsc

100mM

1mM

0.5

H2O

 

 

6.5

 

  • Alexa 488 azide was solved in DMSO
  • Incubation at 37 °C for 12-14 hours (overnight)

Beispieltitel 1

The use of restriction enzymes is no option for cloning if functional nucleic acids contain the recognition sites for enzymes used in standard restriction cloning, as described in RFC 10, or other suitable restriction enzymes. Although techniques using Type IIs restriction enzymes like Golden Gate assembly do not leave scars after cloning, a Type IIs recognition site within the functional RNA sequence may greatly reduce the efficiency and fidelity of a Golden Gate based cloning attempt. Therefore, the method of choice for reliable assembly of the sequences into a standardized vector has to be based on homology at the interfaces of the parts to be fused. As the DNA templates for functional RNA are commonly synthesized de novo, the addition of overhangs upstream and downstream the functional sequence does not appear to be challenging. Equally those extensions can be added during PCR with primer overhangs.

Beispielbild 1
Cooles neues Feature

Google hat neue Effekte

The term “functional RNA” covers a wide range of noncoding natural and synthetic RNA. These RNAs do not need to be translated into protein and are able to fulfil their function either by simple Watson-Crick basepairing interactions or by a more complex formation of secondary structures. Noteworthy classes of functional RNA relevant to the synthetic biologist include:

The term “functional RNA” covers a wide range of noncoding natural and synthetic RNA. These RNAs do not need to be translated into protein and are able to fulfil their function either by simple Watson-Crick basepairing interactions or by a more complex formation of secondary structures. Noteworthy classes of functional RNA relevant to the synthetic biologist include:

Beispielbild 1
Cooles neues Feature

Google hat neue Effekte

Beispielbild 1
Cooles neues Feature

Google hat neue Effekte

Comparison of the cost for the user of antibodies and aptabodies

Cost of antibodies for single use (smalles available size)

The prices of antibodies and aptabodies both in development as well as per use differs drastically. To get an accurate number of cost per use for antibodies, the prices of 4896 aptabodies offered by Thermo Fisher Scientific have been collected and plotted into a histogram. Thermo Fisher Scientific offers only one size for purchase, this equals then the price for the end user for single use. The aptabodies have been sampled pseudo-randomly from the Thermo Fisher Scientific database of "40,000+" antibodies, no currency conversion has been performed and shipping is not considered.

For comparison, the approximate calculated price of an aptabody is shown, see below how this cost is calculated.

Back to Introduction

Copper-catalyzed azide-alkyne cycloaddition (CuAAC)

Sharpless described the copper-catalyzed azide-alkyne cycloaddition (CuAAC) Kolb2001 also called click chemistry. This is due to the simple concept. It works under many different conditions with high yields and no byproducts. Mckay2014 A highly energetic azide reacts with an alkyne enabling a selective reaction that links these reactive groups to one another via a dipolar cycloaddition (Fig. 1). However this reaction requires a lot of activation energy.Zhang2005 Without catalyst the reaction is slow and results in a 1,4, 1,5 triazole regioisomer. To increase the reaction rate and to avoid this byproduct it is necessary to add copper as a catalyst. Copper (Cu(I)) proofed to be a suitable catalyst that rapidly yields a 1,2,3 triazole heterocycle.

Figure 1. Copper-catalyzed azide-alkyne cycloaddition (CuAAC)

Reaction scheme of the CuAAC. Adapted from: Source

Figure 2. Alkyne modification and click reaction of RNA

RNA was 3' modified with alkyne modified nucleotides using yeast Poly(A) Polymerase at 37 °C. Afterwards RNA was precipitated and used for copper click reaction with Alexa 488 azide.

The advantages of a click reaction are that it is very simple and works under many different conditions, as well as that the reaction results in high yields with no byproducts. The highly energetic azides react with alkynes enabling a selective reaction that links reactive groups to one another. To obtain the oxidation state of the copper sodium ascorbate is added to the reaction. Furthermore a ligand like THPTA is necessary to keep the Cu(I) stabilized in aqueous solution.

In order to use the above explained advantages of click chemistry for the labelling of DNA and RNA azide or alkyne modified nucleotides have to be incorporated into the sequence (Fig. 2). Martin et al. have shown that yeast Poly(A) Polymerase is able to incorporate modified nucleotides with small moieties to the 3’ terminus. To obtain an internal modification it is necessary to ligate two part of DNA or RNA to each other via splinted ligation. Winz2012

Summary

The specific monitoring of small molecules in biochemical reactions is problem that scientist tried to solve since many years. In this project we developed small molecule sensor (SMS) enabling us to analyze biochemical reactions in real-time using a fluorescent readout. Our implemented JAWS software generates us the best ATP-binding Aptamer which is fused to the Spinach Aptamer. In presence of ATP fluorescence will be emitted. This tool enables the sensing of small molecules like ATP that are part of biochemical reactions.

Major Achievements:

  • Validation of the JAWS Software
  • Sensing of ATP concentrations in biochemical reactions
  • Establishment of a dual-fluorescent read-out system to sense small molecules in real-time
  • Detailed monitoring of the ATP consumption as well as RNA strand synthesis

Abstract

The specific monitoring of small molecules in biochemical reactions is problem that scientist tried to solve since many years. In this project we developed small molecule sensor (SMS) enabling us to analyze biochemical reactions in real-time using a fluorescent readout. Using this innovative method, we were able to analyze classical in vitro transcriptions in detail by monitoring the ATP consumption as well as RNA strand synthesis simultaneously. Using a Spinach RNA Aptamer fused to an ATP-binding Aptamer RNA we can specifically sense ATP concentrations in real-time. Our implemented JAWS software generates us the best ATP-binding Aptamer. Thus we can even detect small changes in the concentration of ATP during RNA synthesis. To validate the JAWS software as well as to show the general feasibility of our fluorescent tool-box system we analyzed transcription efficiencies of different RNA polymerases, the influence of the buffer as well as the effect of inhibitors like heparin on transcription. Finally, the combination of the JAWS Software and the fluorescent readout enables the scientific community the possibility to target specifically any small molecule of interest in vivo and in vitro.

Introduction

Small molecules are known to regulate many cellular functions. Hence, the development of innovative techniques to analyze metabolic pathways became an important field in research. Those assays require a variety of tools allowing the user to detect small molecules even within live cellsFernandez-Suarez2008Tyagi2009. Such methods hold promise to solve the mechanisms of transcription, translation, localization and the function of non-coding RNA. The most common ways to analyze small molecules or cellular pathways include protein-based methods like GFP or molecule reactive probes which have been engineered in the past. Having a fluorescent readout seems to be a valuable implement to provide time-resolved information in vivo and in vitro. Recently, Paige et al. discovered an RNA that mimics the green fluorescent protein (GFP) so called “Spinach” Paige2011Strack2013Strack2015. This Spinach aptamer was generated by systematic evolution of ligands by exponential enrichment (SELEX). In presence of the 3’5-difluoro-4-hydroxybenzylidne imidazolinone dye (DFHBI), RNA forms a stable Spinach-DFHBI RNA aptamer-complex, which is fluorescent. Since then Spinach has been successfully applied by several laboratories to image RNA in live cellsBuxbaum2015Dean2014. Moreover, this RNA has been used as a tool to monitor RNA synthesis in real-timeHöfer2013Pothoulakis in vitro or to sense different small molecule levels in vivoKellenberger2015Kellenberger2013. A prominent example is the sensing of ci-di-GMP concentrations in live cells. To do so, Kellenberger et al. attached a ci-di-GMP aptamer to the Spinach aptamer. In presence of a small molecule (c-di-GMP) the aptamer forms a functional stem which results in the formation of a fluorescent Spinach-DFHBI RNA aptamer-complex. Thus, small molecule concentrations can be determined by a fluorescence read-out system.

In our project we are interested in small molecules that are difficult to sense using common techniques. Here we will describe an innovative system that uses the Spinach2 fused to a specific aptamer to detect small molecules. In 2013 the Jaffrey Lab developed Spinach2 which shows in comparison to Spinach a better folding efficiency and thermostability. Strack2013. To generate aptamers that specifically bind to a small molecule, we will use our software JAWS. Using this set up we will be able to show that our software is capable to support time consuming methods like SELEX, to identify Aptamers that bind specifically to small molecules. As an interesting target, we will sense the small molecule adenosine triphosphate (ATP) in biochemical reactions. A common method that is performed in thousands of laboratories is a in vitro transcriptions To study the function of ribonucleic acids, RNA is generally prepared by in vitro transcriptionBeckert2011. Using bacteriophage DNA dependent RNA polymerases (T7, T3, Sp6), a variety of different RNAs can be enzymatically synthesized in the lab. In this context we want to establish a new biochemical readout method, called real-time SMS, to record simultaneously small molecules (ATP) and enzymatic kinetics (RNA polymerase) using Spinach2-ATP-Aptamer system.

Aims and Methodoliges

Common techniques to sense small molecules in biochemical reactions are most likely connected to radioactive labeling. The exposure to radioactive sources is known to result in damage of the genetic information and is therefore more and more banished from lab work. However because of its sensitivity, radioactive chemicals are needed to monitor small changes of those molecules. A common method that is performed in many laboratories is an in vitro transcription (Fig. 1A). This method is usually performed in a black-box manner. To analyze the decrease of nucleotide trisphosphate over time as well as to determine the success of the in vitro transcription, scientists use radioactive labelled nucleotide triphosphates and perform time demanding acrylamide gel electrophoresis.

To establish such tool box, two different fluorescent RNA constructs will be applied: The first construct is a fusion of an ATP aptamerSassanfar1993 and Spinach2Strack2013 (Fig. 1B), which we will call Spinach2-ATP-Aptamer system . To improve the binding of the ATP aptamer to ATP we apply our own implemented JAWS software. Using our software, nucleotides which form the stem region of the ATP aptamer can be predicted, which will improve binding properties of this RNA to ATP. The fusion of this aptamer to the Spinach2 enables us a fluorescent read out in real-time. Thus, in presence of this small molecule, the ATP aptamer will form a tight stem loop, which results in a new structural conformation of the Spinach aptamer. Finally after binding of the ATP, the Spinach2-ATP-Aptamer is able to interact with the DFHBI. Hereby fluorescence can be measured at 500 nm if the Spinach was excited at 460 nm. We will generate using our JAWS software different Spinach2-ATP-Aptamers. To validate the software as well as to identify the best Spinach2-ATP-Aptamer system, we will analyze them concerning their fluorescent turn-on effect in presence of ATP.

The second important part of the toolbox is a DNA template containing a promoter according to the applied RNA polymerase and a Malachite Green Aptamer (Fig. 1C), which is excited at 630 nm and emits at 652 nm in presents of malachite green dye. If the Malachite Green Aptamer is transcribed, an increase in fluorescence can be monitored. The second part of the toolbox allows a direct analysis of the success of the in vitro transcription in real-time. In an advanced set up, this system can be extended by DNA template encoding for the RNA of interest (ROI) and a hammerhead ribozyme (HHR). Both fragments are inserted between the promotor and the Malachite Green Aptamer. Inducing the hammerhead ribozyme allows cleavage during the in vitro transcription. Hereby two RNA fragments emerge, the ROI and the hammerhead ribozyme fused to Malachite Green Aptamer (HHR-MGA). Using such setup, the emitted fluorescence of the HHR-MGA will be independent on the applied ROI. Thus the fluorescence induced by the Malachite Green Aptamer can be applied to compare efficiencies of different RNAs at the same time.

The combination of two aptamers that are able to turn on fluorescence by binding to DFHBI or malachite green provide us the possibility to monitor simultaneously the ATP consumption as well as RNA strand synthesis during in vitro transcription in real-time (Fig. 2). The application of the JAWS software generates us the best ATP-aptamer to identify even small changes during RNA synthesis.

To validate the JAWS-generated aptamers as well as to show the functionality of the Spinach2-ATP-Aptamer system we will apply different bacteriophage RNA polymerases (T7, Sp6, T3) that are commonly used. In addition inhibitors (Heparin) of polymerases as well as the effect of different buffer compositions will be analyzed by our approach.

RNA-Spinach2-Template preparation

Spinach2-DNA templates (Table 1) for in vitro transcription were amplified by extension-PCR and purified using Quiaquick PCR Purification Kit or ethanol precipitation. in vitro transcription was performed in presence of 40 mM Tris-HCl pH 8.1, 1 mM spermidine, 20 mM MgCl2, 0.01% Triton-X100, 4 mM each NTP, 10 mM DTT, 5 % DMSO and 0.1 mg/mL T7 RNA Polymerase. DNA was removed by 1 U/ µL DNase I digest. RNA was purified by denaturing PAGE and eluted in 0.3 M NaOAc pH 5.5. RNA was isopropanol precipitated and concentration determined by NanoDrop measurements.

Purified RNA was renatured in 40 mM HEPES KOH pH 7.5, 125 mM KCl and 3 mM MgCl2 and 20 % RNA. Proper folding was achieved by heating up the RNA to 95 °C for 3 min and then letting it cool down to room temperature.

Functionality of the renatured Spinach2 was determined using 500 nM renatured RNA, 1 mM of ligand (e.g. ATP) 100 µM DFHBI (Lucerna) and 0.2 U/µL of Ribolock RNase Inhibitor (Thermo Scientific). The fluorescence spectrum was measured using a spectro fluorometer (JASCO). Then following settings were applied to measure Spinach 2 fluorescence: Ex= 460 nm and Em=475-600 nm, high sensitivity and 37 °C.

Thin Layer Chromatography to Analyze ATP Consumption During in vitro Transcription

Thin layer chromatography will be applied to analyze ATP consumption during in vitro transcription. To analyze ATP consumptions during the RNA transcription, ATP is converted to AMP after the transcription process by apyrase. in vitro transcription was performed in presence of 40 mM Tris-HCl pH 8.1, 1 mM spermidine, 20 mM MgCl2, 0.01% Triton-X100, 4 mM each NTP, 10 mM DTT, 5 % DMSO and 0.1 mg/mL T7 RNA Polymerase. As DNA template we used the ATP AptamerJAWS1 Spinach2. 5 µL samples were taken every 5 min from the reaction and heated up to 95 °C for 10 min to inactivate the T7 RNA polymerase. To convert ATP to AMP 0.01 U Apyrase and 4 mM CaCl2 were added to each sample and incubated for 1 h at 30 °C. 2 µL of each sample was spotted on a fluorophore coated TLC Plat (ALUGRAM®Xtra SIL G/UV254, Macherey Nagel). TLC was run 4 h 45 min 4:6 Ammonium acetat: ethanol and analyzed with a UV lamp.

Malachite Green Aptamer Template Preparation for in vitro Transcription

Malachite Green Aptamer template (10 µM) was hybridized by heating up a forward and reverse oligo to 95 °C. DNA was cooled down to room temperature. dsDNA (Table 2) was then stored at -20 °C.

Malachite Green Aptamer Activity

Malachite Green Aptamer activity was tested by transcribing the prepared DNA-Template in vitro with T7 polymerase as described above and in presence of 1 mM malachite green (Sigma). To ensure synchronic initiation a master mix containing the buffer, enzymes, dye and template were pipetted separately. The assay was performed in 384 well micro titer plates (black, flat round, transparent bottom [Corning, 3540]) on a 20 µL scale. Evaporation during transcription was prevented by using a sealing tape (#232701, Nunc). Measurements on micro titer plates were performed in a microplate reader (Tecan Safire 2). Following parameters were chosen for the assay setup: Ex= 630 nm and Em=652 nm, 10 nm excitation/ emission bandwidth, high sensitivity flash mode and 40 µs integration time. The reaction was measured every 30 sec at 37 °C. To ensure the functionality of the assay, samples of the in vitro transcription were analyzed on a 10 % 8 M urea PAGE.

Time-resolved in vitro Transcription

To describe in vitro transcription time-resolved in terms of NTP consumption, following conditions were applied: 500 nM renatured ATP Aptamer Spinach2 RNA, 10 µM Malachite Green Aptamer DNA template, 40 mM Tris pH 8.1, 1 mM spermidine, 20 mM MgCl2, 0.01% Triton X-100, 4 mM each NTP, 10 mM DTT, 5 % DMSO, 100 µM DFHBI, 1 mM malachite green, 0.1 mg/mL T7 RNA Polymerase, 0.2 U/µL Ribolock RNase and 0.1 U Pyrophosphatase (Thermo Scientific). The assay was performed in 384 well micro titer plates (black, flat round, transparent bottom [Corning, 3540]) on a 20 µL scale. Evaporation during transcription was prevented by using a sealing tape (#232701, Nunc). Measurements on micro titer plates were performed in a microplate reader (Tecan Safire 2).

Influence of Inhibitors on in vitro Transcription

To analyze the influence of inhibitors on the in vitro transcription, heparin (0.7 mg/mL and 1.3 mg/mL) was applied. in vitro transcriptions were performed similar to “time-resolved in vitro Transcription” as described above.

Quantification of RNA Concentrations using Malachite Green Aptamer Fluorescence Read-Out

The T7-Malachite Green DNA template (Table 2) was applied for in vitro transcription as described above. RNA was purified by denaturing PAGE, eluted and recovered by NaOAc/isopropanol precipitation. The RNA was purified from remaining salts using Amicon Ultra-0.5 mL centrifugal filters 3K (Merck Millipore). For preparation of a calibration curve, RNA solutions of different concentrations were refolded (95°C 3min, in 1x renaturing buffer) 7. After addition of 100 µM DFHBI, 100 µM malachite green, 10 mM DTT, 4 mM ATP, 4 mM GTP, 4mM CTP, 4 mM UTP, 1x transcription buffer (1mM spermidine), 0.0017 U pyrophosphatase, 0.46 U Ribolock, 0.075 % glycerol fluorescence, fluorescence was measured on micro titer plates using microplate reader (Tecan Safire 2). Following parameters were chosen for the assay setup: Ex= 630 nm and Em=652 nm, 10 nm excitation/ emission bandwidth, high sensitivity flash mode and 40 µs integration time. The reaction was measured every 30 sec at 37 °C.