Forty Years of Directed Evolution and its Continuously Evolving Technology Toolbox - A Review of the Patent Landscape

Fluorescence coupling strategies in fluorescence-activated droplet sorting (FADS) for ultrahigh-throughput screening of enzymes, metabolites, and antibodies

Fluorescence-activated droplet sorting (FADS) has emerged as a powerful tool for ultrahigh-throughput screening of enzymes, metabolites, and antibodies. Fluorescence coupling strategies (FCSs) are key to the development of new FADS methods through their coupling of analyte properties such as concentration, activities, and affinity with fluorescence signals. Over the last decade, a series of FCSs have been developed, greatly expanding applications of FADS. Here, we review recent advances in FCS for different analyte types, providing a critical comparison of the available FCSs and further classification into four categories according to their principles. We also summarize successful FADS applications employing FCSs in enzymes, metabolites, and antibodies. Further, we outline possible future developments in this area.

Updated analysis to reject the laboratory-engineering hypothesis of SARS-CoV-2

A clear understanding of the origin of SARS-CoV-2 is important for future pandemic preparedness. Here, I provided an updated analysis of the type IIS endonuclease maps in genomes of alphacoronavirus, betacoronavirus, and SARS-CoV-2. Scenarios to engineer SARS-CoV-2 in the laboratory and the associated workload was also discussed. The analysis clearly shows that the endonuclease fingerprint does not indicate a synthetic origin of SARS-CoV-2 and engineering a SARS-CoV-2 virus in the laboratory is extremely challenging both scientifically and financially. On the contrary, current scientific evidence does support the animal origin of SARS-CoV-2.

Progresses in Cell-Free In Vitro Evolution

Biopolymers, such as proteins and RNA, are integral components of living organisms and have evolved through a process of repeated mutation and selection. The technique of "cell-free in vitro evolution" is a powerful experimental approach for developing biopolymers with desired functions and structural properties. Since Spiegelman's pioneering work over 50 years ago, biopolymers with a wide range of functions have been developed using in vitro evolution in cell-free systems. The use of cell-free systems offers several advantages, including the ability to synthesize a wider range of proteins without the limitations imposed by cytotoxicity, and the capacity for higher throughput and larger library sizes than cell-based evolutionary experiments. In this chapter, we provide a comprehensive overview of the progress made in the field of cell-free in vitro evolution by categorizing evolution into directed and undirected. The biopolymers produced by these methods are valuable assets in medicine and industry, and as a means of exploring the potential of biopolymers.

H-Bond Templated Oligomer Synthesis Using a Covalent Primer

Template-directed synthesis of nucleic acids in the polymerase chain reaction is based on the use of a primer, which is elongated in the replication process. The attachment of a high affinity primer to the end of a template chain has been implemented for templating the synthesis of triazole oligomers. A covalent ester base-pair was used to attach a primer to a mixed sequence template. The resulting primed template has phenol recognition units on the template, which can form noncovalent base-pairs with phosphine oxide monomers via H-bonding, and an alkyne group on the primer, which can react with the azide group on a phosphine oxide monomer. Competition reactions between azides bearing phosphine oxide and phenol recognition groups were used to demonstrate a substantial template effect, due to H-bonding interactions between the phenols on the template and phosphine oxides on the azide. The largest rate acceleration was observed when a phosphine oxide 2-mer was used, because this compound binds to the template with a higher affinity than compounds that can only make one H-bond. The ³¹P NMR spectrum of the product duplex shows that the H-bonds responsible for the template effect are present in the product, and this result indicates that the covalent ester base-pairs and noncovalent H-bonded base-pairs developed here are geometrically compatible. Following the templated reaction, it is possible to regenerate the template and liberate the copy strand by hydrolysis of the ester base-pair used to attach the primer, thus completing a formal replication cycle.