Misconceptions of Synthetic Biology: Lessons from an Interdisciplinary Summer School

In 2014, an international group of scholars from various fields analysed the "societal dimensions" of synthetic biology in an interdisciplinary summer school. Here, we report and discuss the biologists' observations on the general perception of synthetic biology by non-biologists who took part in this event. Most attendees mainly associated synthetic biology with contributions from the best-known public figures of the field, rarely mentioning other scientists. Media extrapolations of those contributions appeared to have created unrealistic expectations and irrelevant fears that were widely disconnected from the current research in synthetic biology. Another observation was that when debating developments in synthetic biology, semantics strongly mattered: depending on the terms used to present an application of synthetic biology, attendees reacted in radically different ways. For example, using the term "GMOs" (genetically modified organisms) rather than the term "genetic engineering" led to very different reactions. Stimulating debates also happened with participants having unanticipated points of view, for instance biocentrist ethicists who argued that engineered microbes should not be used for human purposes. Another communication challenge emerged from the connotations and inaccuracies surrounding the word "life", which impaired constructive debates, thus leading to misconceptions about the abilities of scientists to engineer or even create living organisms. Finally, it appeared that synthetic biologists tend to overestimate the knowledge of non-biologists, further affecting communication. The motivation and ability of synthetic biologists to communicate their work outside their research field needs to be fostered, notably towards policymakers who need a more accurate and technical understanding of the field to make informed decisions. Interdisciplinary events gathering scholars working in and around synthetic biology are an effective tool in addressing those issues

Large Phenotypic Enhancement of Structured Random RNA Pools.

Laboratory evolution of functional RNAs has applications in many areas of chemical and synthetic biology. In vitro selections critically depend on the presence of functional molecules, such as aptamers and ribozymes, in the starting sequence pools. For selection of novel functions the pools are typically transcribed from random-sequence DNA templates, yielding a highly diverse set of RNAs that contain a multitude of folds and biochemical activities. The phenotypic potential, the frequency of functional RNAs, is very low, requiring large complexity of starting pools, surpassing 1015 different sequences, to identify highly active isolates. Furthermore, the majority of random sequences is not structured and has a high propensity for aggregation; the in vitro selection process thus involves not just enrichment of functional RNAs, but also their purification from aggregation-prone "free-riders". We reasoned that purification of the nonaggregating, monomeric subpopulation of a random-sequence RNA pool will yield pools of folded, functional RNAs. We performed six rounds of selection for monomeric sequences and show that the enriched population is compactly folded. In vitro selections originating from various mixtures of the compact pool and a fully random pool showed that sequences from the compact pool always dominate the population once a biochemical activity is detectable. A head-to-head competition of the two pools starting from a low (5 × 1012) sequence diversity revealed that the phenotypic potential of the compact pool is about 1000-times higher than the fully random pool. A selection for folded and monomeric RNA pools thus greatly increases the frequency of functional RNAs from that seen in random-sequence pools, providing a facile experimental approach to isolation of highly active functional RNAs from low-diversity populations

Regulation of mRNA translation by a photoriboswitch.

Optogenetic tools have revolutionized the study of receptor-mediated processes, but such tools are lacking for RNA-controlled systems. In particular, light-activated regulatory RNAs are needed for spatiotemporal control of gene expression. To fill this gap, we used in vitro selection to isolate a novel riboswitch that selectively binds the trans isoform of a stiff-stilbene (amino-tSS)-a rapidly and reversibly photoisomerizing small molecule. Structural probing revealed that the RNA binds amino-tSS about 100-times stronger than the cis photoisoform (amino-cSS). In vitro and in vivo functional analysis showed that the riboswitch, termed Werewolf-1 (Were-1), inhibits translation of a downstream open reading frame when bound to amino-tSS. Photoisomerization of the ligand with a sub-millisecond pulse of light induced the protein expression. In contrast, amino-cSS supported protein expression, which was inhibited upon photoisomerization to amino-tSS. Reversible photoregulation of gene expression using a genetically encoded RNA will likely facilitate high-resolution spatiotemporal analysis of complex RNA processes

Integrating artificial with natural cells to translate chemical messages that direct E. coli behaviour

Previous efforts to control cellular behaviour have largely relied upon various forms of genetic engineering. Once the genetic content of a living cell is modified, the behaviour of that cell typically changes as well. However, other methods of cellular control are possible. All cells sense and respond to their environment. Therefore, artificial, non-living cellular mimics could be engineered to activate or repress already existing natural sensory pathways of living cells through chemical communication. Here we describe the construction of such a system. The artificial cells expand the senses of Escherichia coli by translating a chemical message that E. coli cannot sense on its own to a molecule that activates a natural cellular response. This methodology could open new opportunities in engineering cellular behaviour without exploiting genetically modified organisms

The relationship between genotype and phenotype in cell-free transcription-translation reactions.

Cell-free transcription and translation reactions lie at the heart of the rising field known as in vitro synthetic biology and their existence is fundamental for the reconstitution of artificial cells. While researchers are exploring different ways to create such reactions, the common feature that they share is the use of a template DNA to carry the information for the specific function that the reaction is required to perform. The scope of this thesis is to elucidate the relationship between the genotype and the phenotype in such reactions, investigating both transcription and translation using state of the art fluorescence spectroscopy

Enzymatic RNA Production from NTPs Synthesized from Nucleosides and Trimetaphosphate

A mechanism of nucleoside triphosphorylation would have been critical in an evolving “RNA world” to provide high-energy substrates for reactions such as RNA polymerization. However, synthetic approaches to produce ribonucleoside triphosphoates (rNTPs) have suffered from conditions such as high temperatures or high pH that lead to increased RNA degradation, as well as substrate production that cannot sustain replication. We demonstrate that cyclic trimetaphosphate (cTmp) can react with nucleosides to form rNTPs under mild, prebiotically-relevant conditions, with second-order rate constants ranging from 1.7 x 10–6 to 6.5 x 10–6 M–1 s–1. The ATP reaction shows a linear dependence on pH and Mg2+, and an enthalpy of activation of 88 ± 4 kJ/mol. At millimolar nucleoside and cTmp concentrations, the rNTP production rate is sufficient to facilitate RNA synthesis by both T7 RNA polymerase and a polymerase ribozyme. We suggest that the optimized reaction of cTmp with nucleosides may provide a viable connection between prebiotic nucleotide synthesis and RNA replication.</p

Enzymatic RNA Production from NTPs Synthesized from Nucleosides and Trimetaphosphate

&lt;p&gt;A mechanism of nucleoside triphosphorylation would have been critical in an evolving “RNA world” to provide high-energy substrates for reactions such as RNA polymerization. However, synthetic approaches to produce ribonucleoside triphosphoates (rNTPs) have suffered from conditions such as high temperatures or high pH that lead to increased RNA degradation, as well as substrate production that cannot sustain replication. We demonstrate that cyclic trimetaphosphate (cTmp) can react with nucleosides to form rNTPs under mild, prebiotically-relevant conditions, with second-order rate constants ranging from 1.7 x 10&lt;sup&gt;–6&lt;/sup&gt; to 6.5 x 10&lt;sup&gt;–6&lt;/sup&gt; M&lt;sup&gt;–1&lt;/sup&gt; s&lt;sup&gt;–1&lt;/sup&gt;. The ATP reaction shows a linear dependence on pH and Mg&lt;sup&gt;2+&lt;/sup&gt;, and an enthalpy of activation of 88 ± 4 kJ/mol. At millimolar nucleoside and cTmp concentrations, the rNTP production rate is sufficient to facilitate RNA synthesis by both T7 RNA polymerase and a polymerase ribozyme. We suggest that the optimized reaction of cTmp with nucleosides may provide a viable connection between prebiotic nucleotide synthesis and RNA replication.&lt;/p&gt;</jats:p

Cardiac involvement in Churg-Strauss syndrome mimicking acute coronary syndrome

Churg-Strauss syndrome (CSS) is a rare multisystemic disorder of unknown origin and cardiac involvement is one of the most serious manifestations of the disease, accounting for approximately one-half of deaths attributable to CSS. Cardiac manifestation can be acute and mimic acute coronary syndrome (ACS). In this setting checking the blood leucocyte count can reveal hypereosinophilia and lead to a diagnosis of CSS