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Background Efficient cell-free protein expression from linear DNA templates has remained a challenge primarily due to template degradation. In addition, the yields of transcription in cell-free systems lag behind transcriptional efficiency of live cells. Most commonly used in vitro translation systems utilize T7 RNA polymerase, which is also the enzyme included in many commercial kits. Results Here we present characterization of a variant of T7 RNA polymerase promoter that acts to significantly increase the yields of gene expression within in vitro systems. We have demonstrated that T7Max increases the yield of translation in many types of commonly used in vitro protein expression systems. We also demonstrated increased protein expression yields from linear templates, allowing the use of T7Max driven expression from linear templates. Conclusions The modified promoter, termed T7Max, recruits standard T7 RNA polymerase, so no protein engineering is needed to take advantage of this method. This technique could be used with any T7 RNA polymerase- based in vitro protein expression system.

Recently, a new subset of fluorescent proteins has been identified from the Aequorea species of jellyfish. These fluorescent proteins were characterizedin vivo; however, there has not been validation of these proteins within cell-free systems. Cell-free systems and technology development is a rapidly expanding field, encompassing foundational research, synthetic cells, bioengineering, biomanufacturing and drug development. Cell-free systems rely heavily on fluorescent proteins as reporters. Here we characterize and validate this new set of Aequorea proteins for use in a variety of cell-free and synthetic cell expression platforms.Abstract Figure

Synthetic minimal cells provide a controllable and engineerable model for an increasing amount of biological processes. While much simpler than any live natural cell, synthetic cells offer a chassis for investigating the foundations of key biological processes. Here we show a synthetic cell system describing host cells interacting with parasites and infections of varying severity. We demonstrate how the host can be engineered to resist infection, we investigate the metabolic cost of carrying resistance, and we show a simple inoculation system that immunizes the host against pathogens. Our work expands the synthetic cell engineering toolbox by demonstrating host pathogen interactions and mechanisms for acquiring immunity. This brings synthetic cell systems one step closer to providing a comprehensive model of complex, natural life.

On November 5–8, 2019, the “Mars Extant Life: What's Next?” conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia (“oases”), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, but instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques—that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceed the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories and analog field sites and from theoretical modeling.

Synthetic cells can mimic the intricate complexities of live cells, while mitigating the level of noise that is present natural systems; however, many crucial processes still need to be demonstrated in synthetic cells to use them to comprehensively study and engineer biology. Here we demonstrate key functionalities of synthetic cells previously available only to natural life: differentiation and mating. This work presents a toolset for engineering combinatorial genetic circuits in synthetic cells. We demonstrate how progenitor populations can differentiate into new lineages in response to small molecule stimuli or as a result of fusion, and we provide practical demonstration of utility for metabolic engineering. This work provides a tool for bioengineering and for natural pathway studies, as well as paving the way toward the construction of live artificial cells.

Synthetic minimal cells are a class of small liposome bioreactors that have some, but not all functions of live cells. Here, we report a critical step towards the development of a bottom-up minimal cell: cellular export of functional protein and RNA products. We used cell penetrating peptide tags to translocate payloads across a synthetic cell vesicle membrane. We demonstrated efficient transport of active enzymes, and transport of nucleic acid payloads by RNA binding proteins. We investigated influence of a concentration gradient alongside other factors on the efficiency of the translocation, and we show a method to increase product accumulation in one location. We demonstrate the use of this technology to engineer molecular communication between different populations of synthetic cells, to exchange protein and nucleic acid signals. The synthetic minimal cell production and export of proteins or nucleic acids allows experimental designs that approach the complexity and relevancy of natural biological systems.

Cell-free protein expression is increasingly becoming popular for biotechnology, biomedical and research applications. Among cell-free systems, the most popular one is based on Escherichia coli (E. coli). Endogenous nucleases in E. coli cell-free transcription-translation (TXTL) degrade the free ends of DNA, resulting in inefficient protein expression from linear DNA templates. RecBCD is a nuclease complex that plays a major role in nuclease activity in E. coli, with the RecB subunit possessing the actual nuclease activity. We created a RecB knockout of an E. coli strain optimized for cell-free expression. We named this new strain Akaby. We demonstrated that Akaby TXTL successfully reduced linear DNA degradations, rescuing the protein expression efficiency from the linear DNA templates. The practicality of Akaby for TXTL is an efficient, simple alternative for linear template expression in cell-free reactions. We also use this work as a model protocol for modifying the TXTL source E. coli strain, enabling the creation of TXTL systems with other custom modifications.

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, poses grave threats to both the global economy and health. The predominant diagnostic screens in use for SARS-CoV-2 detection are molecular techniques such as nucleic acid amplification tests. In this Review, we compare current and emerging isothermal diagnostic methods for COVID-19. We outline the molecular and serological techniques currently being used to detect SARS-CoV-2 infection, past or present, in patients. We also discuss ongoing research on isothermal techniques, CRISPR-mediated detection assays, and point-of-care diagnostics that have potential for use in SARS-CoV-2 detection. Large-scale viral testing during a global pandemic presents unique challenges, chief among them the simultaneous need for testing supplies, durable equipment, and personnel in many regions worldwide, with each of these regions possessing testing needs that vary as the pandemic progresses. The low-cost isothermal technologies described in this Review provide a promising means by which to address these needs and meet the global need for testing of symptomatic individuals as well as provide a possible means for routine testing of asymptomatic individuals, providing a potential means of safely enabling reopenings and early monitoring of outbreaks.

Structural biology education commonly employs molecular visualization software, such as PyMol, RasMol, and VMD, to allow students to appreciate structure-function relationships in biomolecules. In on-ground, classroom-based education, these programs are commonly used on University-owned devices with software preinstalled. Remote education typically involves the use of student-owned devices, which complicates the use of such software, owing to the fact that (a) student devices have differing configurations (e.g., Windows vs MacOS) and processing power, and (b) not all student devices are suitable for use with such software. Smartphones are near-ubiquitous devices, with smartphone ownership exceeding personal computer ownership, according to a recent survey. Here, we show the use of a smartphone-based augmented reality app, Augment, in a structural biology classroom exercise, which students installed independently without IT support. Post-lab attitudinal survey results indicate positive student experiences with this app. Based on our experiences, we suggest that smartphone-based molecular visualization software, such as that used in this exercise, is a powerful educational tool that is particularly well-suited for use in remote education.

Isothermal, cell-free, synthetic biology-based approaches to pathogen detection leverage the power of tools available in biological systems, such as highly active polymerases compatible with lyophilization, without the complexity inherent to live-cell systems, of which Nucleic Acid Sequence Based Amplification (NASBA) is well known. Despite the reduced complexity associated with cell-free systems, side reactions are a common characteristic of these systems. As a result, these systems often exhibit false positives from reactions lacking an amplicon. Here we show that the inclusion of a DNA duplex lacking a promoter and unassociated with the amplicon, fully suppresses false positives, enabling a suite of fluorescent aptamers to be used as NASBA tags (Apta-NASBA). Apta-NASBA has a 1 pM detection limit and can provide multiplexed, multicolor fluorescent readout. Furthermore, Apta-NASBA can be performed using a variety of equipment, for example a fluorescence microplate reader, a qPCR instrument, or an ultra-low-cost Raspberry Pi-based 3D-printed detection platform employing a cell phone camera module, compatible with field detection.

Cell-free protein expression is increasingly becoming popular for biotechnology, biomedical and research applications. Among cell-free systems, the most popular one is based on Escherichia coli (E. coli). Endogenous nucleases in E. coli cell-free transcription-translation (TXTL) degrade the free ends of DNA, resulting in inefficient protein expression from linear DNA templates. RecBCD is a nuclease complex that plays a major role in nuclease activity in E. coli, with the RecB subunit possessing the actual nuclease activity. We created a RecB knockout of an E. coli strain optimized for cell-free expression. We named this new strain Akaby. We demonstrated that Akaby TXTL successfully reduced linear DNA degradations, rescuing the protein expression efficiency from the linear DNA templates. The practicality of Akaby for TXTL is an efficient, simple alternative for linear template expression in cell-free reactions. We also use this work as a model protocol for modifying the TXTL source E. coli strain, enabling the creation of TXTL systems with other custom modifications.

The study of nonenzymatic template-directed RNA copying is the experimental basis for the search for chemistry and reaction conditions consistent with prebiotic RNA replication. The most effective model systems for RNA copying have to date required a high concentration of Mg2+. Recently, Fe2+, which was abundant on the prebiotic anoxic Earth, was shown to promote the folding of RNA in a manner similar to the case of Mg2+, as a result of the two cations having similar interactions with phosphate groups. These observations raise the question of whether Fe2+ could have promoted RNA copying on the prebiotic Earth. Here, we demonstrate that Fe2+ is a better catalyst and promotes faster nonenzymatic RNA primer extension and ligation than Mg2+ when using 2-methylimidazole activated nucleotides in slightly acidic to neutral pH solutions. Thus, it appears likely that Fe2+ could have facilitated RNA replication and evolution in concert with other metal cations on the prebiotic Earth.

A teaching laboratory experiment is described where students prepare in vitro transcription reactions of a fluorescent RNA aptamer, named Broccoli, and observe the production of the aptamer in real...

Thermal denaturation is a common technique in the biophysical study of nucleic acids. These experiments are typically performed by monitoring the increase in absorbance (hyperchromism) of a sample at 260nm with temperature (MergnyLacroix, 2003; PuglisiTinoco, 1989). This wavelength is chosen as nucleic acids of mixed sequence typically exhibit their maximum absorbance here. Exceptions exist, however, some noncanonical nucleic acid structures exhibit differing spectral changes with temperature, resulting in other wavelengths being convenient reporters of secondary structure. In the case of nucleic acids that bind visible light-absorbing ligands, such as fluorogenic aptamers, another wavelength can be a convenient reporter of secondary structure stability and RNA-ligand recognition. As it can be difficult, if not impossible, to know which wavelength to employ a priori, we have developed a system for obtaining the full UV-visible spectrum of a sample at each wavelength, allowing for the subsequent extraction of the absorbance-temperature profile at the desired wavelength. Here, we describe the apparatus and software used to do so. We also describe another technique for the use of a qPCR instrument for measuring secondary structure stability of fluorescent nucleic acid-ligand complexes.

The emergence of homeostatic mechanisms that enable maintenance of an intracellular steady state during growth was critical to the advent of cellular life. Here, we show that concentration-dependent reversible binding of short oligonucleotides, of both specific and random sequence, can modulate ribozyme activity. In both cases, catalysis is inhibited at high concentrations, and dilution activates the ribozyme via inhibitor dissociation, thus maintaining near-constant ribozyme specific activity throughout protocell growth. To mimic the result of RNA synthesis within non-growing protocells, we co-encapsulated high concentrations of ribozyme and oligonucleotides within fatty acid vesicles, and ribozyme activity was inhibited. Following vesicle growth, the resulting internal dilution produced ribozyme activation. This simple physical system enables a primitive homeostatic behaviour: the maintenance of constant ribozyme activity per unit volume during protocell volume changes. We suggest that such systems, wherein short oligonucleotides reversibly inhibit functional RNAs, could have preceded sophisticated modern RNA regulatory mechanisms, such as those involving miRNAs.

Thermal denaturation is a common technique in the biophysical study of nucleic acids. These experiments are typically performed by monitoring the increase in absorbance (hyperchromism) of a sample at 260nm with temperature (Mergny & Lacroix, 2003; Puglisi & Tinoco, 1989). This wavelength is chosen as nucleic acids of mixed sequence typically exhibit their maximum absorbance here. Exceptions exist, however, some noncanonical nucleic acid structures exhibit differing spectral changes with temperature, resulting in other wavelengths being convenient reporters of secondary structure. In the case of nucleic acids that bind visible light-absorbing ligands, such as fluorogenic aptamers, another wavelength can be a convenient reporter of secondary structure stability and RNA-ligand recognition. As it can be difficult, if not impossible, to know which wavelength to employ a priori, we have developed a system for obtaining the full UV-visible spectrum of a sample at each wavelength, allowing for the subsequent extraction of the absorbance-temperature profile at the desired wavelength. Here, we describe the apparatus and software used to do so. We also describe another technique for the use of a qPCR instrument for measuring secondary structure stability of fluorescent nucleic acid-ligand complexes.

Liposomes containing single-chain amphiphiles, particularly fatty acids, exhibit distinct properties compared to those containing diacylphospholipids due to the unique chemical properties of these amphiphiles. In particular, fatty acid liposomes enhance dynamic character, due to the relatively high solubility of single-chain amphiphiles. Similarly, liposomes containing free fatty acids are more sensitive to salt and divalent cations, due to the strong interactions between the carboxylic acid head groups and metal ions. Here we illustrate techniques for preparation, purification, and use of liposomes comprised in part or whole of single chain amphiphiles (e.g., oleic acids).

The liposome dialyzer is a small-volume equilibrium dialysis device, built from commercially available materials, that is designed for the rapid exchange of small volumes of an extraliposomal reagent pool against a liposome preparation. The dialyzer is prepared by modification of commercially available dialysis cartridges (Slide-A-Lyzer cassettes), and it consists of a reactor with two 300-μl chambers and a 1.56-cm(2) dialysis surface area. The dialyzer is prepared in three stages: (i) disassembling the dialysis cartridges to obtain the required parts, (ii) assembling the dialyzer and (iii) sealing the dialyzer with epoxy. Preparation of the dialyzer takes ∼1.5 h, not including overnight epoxy curing. Each round of dialysis takes 1-24 h, depending on the analyte and membrane used. We previously used the dialyzer for small-volume non-enzymatic RNA synthesis reactions inside fatty acid vesicles. In this protocol, we demonstrate other applications, including removal of unencapsulated calcein from vesicles, remote loading and vesicle microscopy.

Biopolymers exist within living cells as far-from-equilibrium metastable polymers. Living systems must constantly invest energy for biopolymer synthesis. In the earliest stages of life on Earth, the complex molecular machinery that contemporary life employs for the synthesis and maintenance of polymers did not exist. Thus, a major question regarding the origin of life is how the first far-from-equilibrium polymers emerged from a prebiotic “pool” of monomers. Here, we describe a proof-of-principle system, in which l-malic acid monomers form far-from-equilibrium, metastable oligoesters via repeated, cyclic changes in hydration and temperature. Such cycles would have been associated with day–night and/or seasonal cycles on the early Earth. In our model system, sample heating, which promotes water evaporation and ester bond formation, drives polymerization. Even though periodic sample rehydration and heating in the hydrated state promotes ester bond hydrolysis, successive iterations of wet–dry cycles result i...

A plausible process for non-enzymatic RNA replication would greatly simplify models of the transition from prebiotic chemistry to simple biology. However, all known conditions for the chemical copying of an RNA template result in the synthesis of a complementary strand that contains a mixture of 2'-5' and 3'-5' linkages, rather than the selective synthesis of only 3'-5' linkages as found in contemporary RNA. Here we show that such backbone heterogeneity is compatible with RNA folding into defined three-dimensional structures that retain molecular recognition and catalytic properties and, therefore, would not prevent the evolution of functional RNAs such as ribozymes. Moreover, the same backbone heterogeneity lowers the melting temperature of RNA duplexes that would otherwise be too stable for thermal strand separation. By allowing copied strands to dissociate, this heterogeneity may have been one of the essential features that allowed RNA to emerge as the first biopolymer.

Nonenzymatic DNA ligation chemistries containing a reversible step allow thermodynamic control of product formation, but they are not necessarily compatible with polymerase enzymes. We report a ligation system that uses commercially available reagents, includes a reversible step, and results in a linkage that can function as a template for PCR amplification with accurate sequence transfer.

In contrast to proteins, no intrinsically fluorescent RNA is known to exist in nature. In this issue, a new, red-shifted aptamer–fluorophore complex for RNA imaging that has enhanced photostability is described. The crystal structure of this complex reveals a novel form of RNA small-molecule recognition.

The mixture of 2′-5′ and 3′-5′ linkages generated during the nonenzymatic replication of RNA has long been regarded as a central problem for the origin of the RNA world. However, we recently observed that both a ribozyme and an RNA aptamer retain considerable functionality in the presence of prebiotically plausible levels of linkage heterogeneity. To better understand the RNA structure and function in the presence of backbone linkage heterogeneity, we obtained high-resolution X-ray crystal structures of a native 10-mer RNA duplex (1.32 A) and two variants: one containing one 2′-5′ linkage per strand (1.55 A) and one containing three such linkages per strand (1.20 A). We found that RNA duplexes adjust their local structures to accommodate the perturbation caused by 2′-5′ linkages, with the flanking nucleotides buffering the disruptive effects of the isomeric linkage and resulting in a minimally altered global structure. Although most 2′-linked sugars were in the expected 2′-endo conformation, some were partially or fully in the 3′-endo conformation, suggesting that the energy difference between these conformations was relatively small. Our structural and molecular dynamic studies also provide insight into the diminished thermal and chemical stability of the duplex state associated with the presence of 2′-5′ linkages. Our results contribute to the view that a low level of 2′-5′ substitution would not have been fatal in an early RNA world and may in contrast have been helpful for both the emergence of nonenzymatic RNA replication and the early evolution of functional RNAs.

Since the structure of DNA was elucidated more than 50 years ago, Watson-Crick base pairing has been widely speculated to be the likely mode of both information storage and transfer in the earliest genetic polymers. The discovery of catalytic RNA molecules subsequently provided support for the hypothesis that RNA was perhaps even the first polymer of life. However, the de novo synthesis of RNA using only plausible prebiotic chemistry has proven difficult, to say the least. Experimental investigations, made possible by the application of synthetic and physical organic chemistry, have now provided evidence that the nucleobases (A, G, C, and T/U), the trifunctional moiety ([deoxy]ribose), and the linkage chemistry (phosphate esters) of contemporary nucleic acids may be optimally suited for their present roles-a situation that suggests refinement by evolution. Here, we consider studies of variations in these three distinct components of nucleic acids with regard to the question: Is RNA, as is generally acknowledged of DNA, the product of evolution? If so, what chemical and structural features might have been more likely and advantageous for a proto-RNA?

DNA oligonucleotides containing 8-aminodeoxyguanosine residues form a pH-dependent self-structure with strong hydrogen bonds.

We found that several major chromosomal fragile sites in human lymphomas, including the bcl-2 major breakpoint region, bcl-1 major translocation cluster, and c-Myc exon 1-intron 1 boundary, contain distinctive sequences of consecutive cytosines exhibiting a high degree of reactivity with the structure-specific chemical probe bisulfite. To assess the inherent structural variability of duplex DNA in these regions and to determine the range of structures reactive to bisulfite, we have performed bisulfite probing on genomic DNA in vitro and in situ; on duplex DNA in supercoiled and linearized plasmids; and on oligonucleotide DNA/DNA and DNA/2′-O-methyl RNA duplexes. Bisulfite is significantly more reactive at the frayed ends of DNA duplexes, which is expected given that bisulfite is an established probe of single-stranded DNA. We observed that bisulfite also distinguishes between more subtle sequence/structural differences in duplex DNA. Supercoiled plasmids are more reactive than linear DNA; and sequences containing consecutive cytosines, namely GGGCCC, are more reactive than those with alternating guanine and cytosine, namely GCGCGC. Circular dichroism and x-ray crystallography show that the GGGCCC sequence forms an intermediate B/A structure. Molecular dynamics simulations also predict an intermediate B/A structure for this sequence, and probe calculations suggest greater bisulfite accessibility of cytosine bases in the intermediate B/A structure over canonical B- or A-form DNA. Electrostatic calculations reveal that consecutive cytosine bases create electropositive patches in the major groove, predicting enhanced localization of the bisulfite anion at homo-C tracts over alternating G/C sequences. These characteristics of homo-C tracts in duplex DNA may be associated with DNA-protein interactions in vivo that predispose certain genomic regions to chromosomal fragility.

A number of DNA secondary structures are known in addition to the Watson–Crick double helix. From the perspective of nucleic acid–metal ion interactions, the G-quadruplex is certainly the most unique and interesting DNA secondary structure. Additionally, G-quadruplexes are currently of significant m...

The common depiction of DNA as a homogeneous double helix, although aesthetically pleasing, is an inadequate model for understanding how DNA functions within the cell. High-resolution crystal structures and spectroscopic data have revealed considerable sequence-specific structural variations in the ...

The discovery of G-quadruplex structures in nucleic acid sequences associated with cancers has created intense interest in G quadruplexes as potential drug targets. These fourstranded structures, with planar G tetrads represent appealing DNA targets (Figure 1A), as they are structurally distinct from the Watson–Crick duplex of most genomic DNA. Small molecules with high affinity and high selectivity for G quadruplexes have even begun to show medicinal promise, although the connection between G-quadruplex binding and in vivo activity might not always be obvious. As one promising example, quarfloxin, an antineoplastic that targets the rRNA–nucleolin complex, is presently in phase II clinical trials. Most investigators who seek new ligands for G-quadruplex DNA have followed two common strategies. First, they have focused on heterocycles with a relatively large and planar surface area, which maximizes stacking with the about 1 nm surface of a G tetrad (e.g. , TmPyP4, Figure 1C). Second, many have used multiple charges to increase electrostatic interactions with the high-charge density G quadruplex (e.g. , BRACO-19, Figure 1D) and to enhance the solubility of potential ligands (often necessary for ligands with large hydrophobic surfaces, e.g. , TmPyP4). While these strategies have resulted in several high affinity ligands for G quadruplexes, most ligands do not exhibit high selectivity over duplex DNA. Recently, several metallated quadruplex ligands have been reported with substantial selectivity for quadruplex DNA. As the authors have suggested, this could be, in part, due to ACHTUNGTRENNUNGinteractions between the metal ion and the lone pairs of the carbonyl oxygen atoms of the exterior quartets, which are not accessible in duplex DNA. Higher-throughput, more combinatorial approaches have begun to show promise as well. For example, Balasubmaranian and co-workers have recently demonstrated dynamic combinatorial selection of quadruplex ligands by disulfide bond formation with a thiol-containing scaffold and side chains. We have taken a different approach to targeting the G quadruplex. We previously discovered that a planar molecule larger than a typical DNA intercalator can selectively bind purine–purine base pairs. Based upon this discovery, we hypothesized that planar, monocationic molecules that are marginally too large to intercalate a Watson–Crick duplex, such as bispurine analogues, might selectively bind G quadruplexes. We report a new class of selective, submicromolar quadruplex ligands with a facile synthetic route: the azacyanines (Figure 1B). The synthesis of azacyanines was previously reported by Kurth and co-workers ; the route is one-pot and workup is by filtration. The route is general and succeeds for aminobenzimidazoles and aminobenzothiazoles. The synthetic ease makes the class amenable to library preparation for highthroughput screening. We investigated the binding of azacyanines to a G-quadruplex sequence, based on the human telomeric repeat dACHTUNGTRENNUNG(TTA

Contemporary life synthesizes RNA of homogeneous length and regioisomer composition via sophisticated enzymatic catalysis. Before such catalysts existed, RNA could have been produced only via simpler, non-enzymatic means, which model prebiotic systems have shown produce pools of products that are similar, but varied (e.g. in regioisomer composition). Recently, we have demonstrated that functional RNAs (ribozymes and aptamers) containing mixed-regioisomer backbones (i.e. 2′–5′ vs. 3′–5′ linkages) retain function. This observation, coupled with the well-known fact that mixed-regioisomer RNAs exhibit depressed melting temperatures relative to native RNA, suggests that mixed-regioisomer backbones could actually be adaptive in an RNA (or pre-RNA) world. In this poster, we will show our recent work with functional RNAs representative of those produced in non-enzymatic polymerization reactions and their behaviours as catalysts and receptors.

A collection of articles in this issue focuses on the chemical origin of life — how simple molecules present on the early Earth could have evolved into the complex dynamic biochemistry that we know today.

RNA can play dual roles as a carrier of genetic information and as a catalyst of specific reactions, and it may have been the first biopolymer to have emerged on the early earth. The non-enzymatic ...