DNA-based enzymatic systems and their applications

MicroRNA biosensors for detection of chronic kidney disease

Chronic kidney disease (CKD) is a prevalent health condition characterized by gradual kidney function loss. Early detection is crucial for the effective management and treatment of CKD. A promising biomarker for various diseases, including chronic kidney disease, is microRNAs (miRNAs), which are becoming increasingly important due to their stability and differential expression in various disease-related states, including CKD. Recent developments in microRNA biosensors have made it possible to detect miRNAs associated with CKD in a sensitive and specific manner. This review article discusses the current state of microRNA biosensors for detecting CKD and highlights their potential applications in clinical settings. Various microRNA biosensors, including electrochemical, optical, and nanomaterial-based sensors, are explored for their ability to detect specific miRNAs linked to CKD progression. The advantages and limitations of these biosensors are evaluated, focusing on factors such as sensitivity, specificity, and ease of use. Overall, microRNA biosensors are promising diagnostic tools for early detection of CKD. However, challenges such as standardizing protocols, validating in large cohorts, and translating to clinical practice remain to be addressed. Future research efforts should aim to overcome these limitations to fully realize the potential of microRNA biosensors in improving the diagnosis and management of CKD.

Pore Engineering as a General Strategy to Improve Protein-Based Enzyme Nanoreactor Performance

Enzyme nanoreactors are nanoscale compartments consisting of encapsulated enzymes and a selectively permeable barrier. Sequestration and colocalization of enzymes can increase catalytic activity, stability, and longevity, highly desirable features for many biotechnological and biomedical applications of enzyme catalysts. One promising strategy to construct enzyme nanoreactors is to repurpose protein nanocages found in nature. However, protein-based enzyme nanoreactors often exhibit decreased catalytic activity, partially caused by a mismatch of protein shell selectivity and the substrate requirements of encapsulated enzymes. No broadly applicable and modular protein-based nanoreactor platform is currently available. Here, we introduce a pore-engineered universal enzyme nanoreactor platform based on encapsulins-microbial self-assembling protein nanocompartments with programmable and selective enzyme packaging capabilities. We structurally characterize our protein shell designs via cryo-electron microscopy and highlight their polymorphic nature. Through fluorescence polarization assays, we show their improved molecular flux behavior and highlight their expanded substrate range via a number of proof-of-concept enzyme nanoreactor designs. This work lays the foundation for utilizing our encapsulin-based nanoreactor platform for diverse future biotechnological and biomedical applications.

Exploring Emergent Properties in Enzymatic Reaction Networks: Design and Control of Dynamic Functional Systems

The intricate and complex features of enzymatic reaction networks (ERNs) play a key role in the emergence and sustenance of life. Constructing such networks in vitro enables stepwise build up in complexity and introduces the opportunity to control enzymatic activity using physicochemical stimuli. Rational design and modulation of network motifs enable the engineering of artificial systems with emergent functionalities. Such functional systems are useful for a variety of reasons such as creating new-to-nature dynamic materials, producing value-added chemicals, constructing metabolic modules for synthetic cells, and even enabling molecular computation. In this review, we offer insights into the chemical characteristics of ERNs while also delving into their potential applications and associated challenges.

Dominant Analytical Techniques in DNA Nanotechnology for Various Applications

DNA nanotechnology is rapidly gaining traction in numerous applications, each bearing varying degrees of tolerance to the quality and quantity necessary for viable nanostructure function. Despite the distinct objectives of each application, they are united in their reliance on essential analytical techniques, such as purification and characterization. This tutorial aims to guide the reader through the current state of DNA nanotechnology analytical chemistry, outlining important factors to consider when designing, assembling, purifying, and characterizing a DNA nanostructure for downstream applications.

Cleaving Folded RNA with DNAzyme Agents

Cleavage of biological mRNA by DNAzymes (Dz) has been proposed as a variation of oligonucleotide gene therapy (OGT). The design of Dz-based OGT agents includes computational prediction of two RNA-binding arms with low affinity (melting temperatures (Tm ) close to the reaction temperature of 37 °C) to avoid product inhibition and maintain high specificity. However, RNA cleavage might be limited by the RNA binding step especially if the RNA is folded in secondary structures. This calls for the need for two high-affinity RNA-binding arms. In this study, we optimized 10-23 Dz-based OGT agents for cleavage of three RNA targets with different folding energies under multiple turnover conditions in 2 mM Mg2+ at 37 °C. Unexpectedly, one optimized Dz had each RNA-binding arm with a Tm ≥60 °C, without suffering from product inhibition or low selectivity. This phenomenon was explained by the folding of the RNA cleavage products into stable secondary structures. This result suggests that Dz with long (high affinity) RNA-binding arms should not be excluded from the candidate pool for OGT agents. Rather, analysis of the cleavage products' folding should be included in Dz selection algorithms. The Dz optimization workflow should include testing with folded rather than linear RNA substrates.

Supramolecular enzyme-mimicking catalysts self-assembled from peptides

Natural enzymes catalyze biochemical transformations in superior catalytic efficiency and remarkable substrate specificity. The excellent catalytic repertoire of enzymes is attributed to the sophisticated chemical structures of their active sites, as a result of billions-of-years natural evolution. However, large-scale practical applications of natural enzymes are restricted due to their poor stability, difficulty in modification, and high costs of production. One viable solution is to fabricate supramolecular catalysts with enzyme-mimetic active sites. In this review, we introduce the principles and strategies of designing peptide-based artificial enzymes which display catalytic activities similar to those of natural enzymes, such as aldolases, laccases, peroxidases, and hydrolases (mainly the esterases and phosphatases). We also discuss some multifunctional enzyme-mimicking systems which are capable of catalyzing orthogonal or cascade reactions. We highlight the relationship between structures of enzyme-like active sites and the catalytic properties, as well as the significance of these studies from an evolutionary point of view.

Mechanistic Aspects for the Modulation of Enzyme Reactions on the DNA Scaffold

Cells have developed intelligent systems to implement the complex and efficient enzyme cascade reactions via the strategies of organelles, bacterial microcompartments and enzyme complexes. The scaffolds such as the membrane or protein in the cell are believed to assist the co-localization of enzymes and enhance the enzymatic reactions. Inspired by nature, enzymes have been located on a wide variety of carriers, among which DNA scaffolds attract great interest for their programmability and addressability. Integrating these properties with the versatile DNA–protein conjugation methods enables the spatial arrangement of enzymes on the DNA scaffold with precise control over the interenzyme distance and enzyme stoichiometry. In this review, we survey the reactions of a single type of enzyme on the DNA scaffold and discuss the proposed mechanisms for the catalytic enhancement of DNA-scaffolded enzymes. We also review the current progress of enzyme cascade reactions on the DNA scaffold and discuss the factors enhancing the enzyme cascade reaction efficiency. This review highlights the mechanistic aspects for the modulation of enzymatic reactions on the DNA scaffold.