1
|
Engineering Aptazyme Switches for Conditional Gene Expression in Mammalian Cells Utilizing an In Vivo Screening Approach. Methods Mol Biol 2021. [PMID: 34086282 DOI: 10.1007/978-1-0716-1499-0_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Artificial RNA switches are an emerging class of genetic controllers suitable for synthetic biology applications. Aptazymes are fusions composed of an aptamer domain and a self-cleaving ribozyme. The utilization of aptazymes for conditional gene expression displays several advantages over employing conventional transcription factor-based techniques as aptazymes require minimal genomic space, fulfill their function without the need of protein cofactors and most importantly are reprogrammable with respect to ligand selectivity and the RNA function to be regulated. Technologies that enable the generation of aptazymes to defined input ligands are of interest for the construction of biocomputing devices and biosensing applications. In this chapter we present a method that facilitates the in vivo screening of randomized pools of aptazymes in mammalian cells.
Collapse
|
2
|
Hieronymus R, Müller S. Towards Higher Complexity in the RNA World: Hairpin Ribozyme Supported RNA Recombination. CHEMSYSTEMSCHEM 2021. [DOI: 10.1002/syst.202100003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Robert Hieronymus
- Institute for Biochemistry University Greifswald Felix-Hausdorff-Str. 4 17487 Greifswald Germany
| | - Sabine Müller
- Institute for Biochemistry University Greifswald Felix-Hausdorff-Str. 4 17487 Greifswald Germany
| |
Collapse
|
3
|
Dagenais P, Legault P. In Vitro Selection of Varkud Satellite Ribozyme Variants that Cleave a Modified Stem-Loop Substrate. Methods Mol Biol 2021; 2167:61-77. [PMID: 32712915 DOI: 10.1007/978-1-0716-0716-9_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In vitro selection is an established approach to create artificial ribozymes with defined activities or to modify the properties of naturally occurring ribozymes. For the Varkud satellite ribozyme of Neurospora, an in vitro selection protocol based on its phosphodiester bond cleavage activity has not been previously reported. Here, we describe a simple protocol for cleavage-based in vitro selection that we recently used to identify variants of the Varkud satellite ribozyme able to target and cleave a non-natural stem-loop substrate derived from the HIV-1 TAR RNA. It allows quick selection of active ribozyme variants from the transcription reaction based on the size of the self-cleavage product without the need for RNA labeling. This results in a streamlined procedure that is easily adaptable to engineer ribozymes with new activities.
Collapse
Affiliation(s)
- Pierre Dagenais
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montreal, QC, Canada
| | - Pascale Legault
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montreal, QC, Canada.
| |
Collapse
|
4
|
Ma L, Liu J. Catalytic Nucleic Acids: Biochemistry, Chemical Biology, Biosensors, and Nanotechnology. iScience 2020; 23:100815. [PMID: 31954323 PMCID: PMC6962706 DOI: 10.1016/j.isci.2019.100815] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/11/2019] [Accepted: 12/26/2019] [Indexed: 01/06/2023] Open
Abstract
Since the initial discovery of ribozymes in the early 1980s, catalytic nucleic acids have been used in different areas. Compared with protein enzymes, catalytic nucleic acids are programmable in structure, easy to modify, and more stable especially for DNA. We take a historic view to summarize a few main interdisciplinary areas of research on nucleic acid enzymes that may have broader impacts. Early efforts on ribozymes in the 1980s have broken the notion that all enzymes are proteins, supplying new evidence for the RNA world hypothesis. In 1994, the first catalytic DNA (DNAzyme) was reported. Since 2000, the biosensor applications of DNAzymes have emerged and DNAzymes are particularly useful for detecting metal ions, a challenging task for enzymes and antibodies. Combined with nanotechnology, DNAzymes are key building elements for switches allowing dynamic control of materials assembly. The search for new DNAzymes and ribozymes is facilitated by developments in DNA sequencing and computational algorithms, further broadening our fundamental understanding of their biochemistry.
Collapse
Affiliation(s)
- Lingzi Ma
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Juewen Liu
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
| |
Collapse
|
5
|
A tRNA- and Anticodon-Centric View of the Evolution of Aminoacyl-tRNA Synthetases, tRNAomes, and the Genetic Code. Life (Basel) 2019; 9:life9020037. [PMID: 31060233 PMCID: PMC6616430 DOI: 10.3390/life9020037] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/24/2019] [Accepted: 05/01/2019] [Indexed: 11/25/2022] Open
Abstract
Pathways of standard genetic code evolution remain conserved and apparent, particularly upon analysis of aminoacyl-tRNA synthetase (aaRS) lineages. Despite having incompatible active site folds, class I and class II aaRS are homologs by sequence. Specifically, structural class IA aaRS enzymes derive from class IIA aaRS enzymes by in-frame extension of the protein N-terminus and by an alternate fold nucleated by the N-terminal extension. The divergence of aaRS enzymes in the class I and class II clades was analyzed using the Phyre2 protein fold recognition server. The class I aaRS radiated from the class IA enzymes, and the class II aaRS radiated from the class IIA enzymes. The radiations of aaRS enzymes bolster the coevolution theory for evolution of the amino acids, tRNAomes, the genetic code, and aaRS enzymes and support a tRNA anticodon-centric perspective. We posit that second- and third-position tRNA anticodon sequence preference (C>(U~G)>A) powerfully selected the sectoring pathway for the code. GlyRS-IIA appears to have been the primordial aaRS from which all aaRS enzymes evolved, and glycine appears to have been the primordial amino acid around which the genetic code evolved.
Collapse
|
6
|
Abstract
Recent advances in RNA engineering during the last two decades have supported the development of RNA-based therapeutics targeting a variety of human diseases. The broad scope of these emerging drugs clearly demonstrates the versatility of RNA. Ribozymes have been seen as promising candidates in this area. However, efficient intracellular application of ribozymes remains challenging, and other strategies appear to have outperformed ribozymes as molecular drugs. Nevertheless, trans-cleaving ribozymes have been applied for specific cleavage of target mRNAs in order to inhibit undesired gene expression. Furthermore, ribozymes have been engineered to allow site-directed RNA sequence alterations, enabling the correction of genetic misinformation at the RNA level. This chapter provides an overview of ribozyme-based strategies, highlighting the promises and pitfalls for potential therapeutic applications.
Collapse
Affiliation(s)
- Darko Balke
- University of Greifswald, Institute of Biochemistry Felix-Hausdorff-Str. 4 17487 Greifswald Germany
| | - Sabine Müller
- University of Greifswald, Institute of Biochemistry Felix-Hausdorff-Str. 4 17487 Greifswald Germany
| |
Collapse
|
7
|
Rehm C, Klauser B, Hartig JS. Engineering aptazyme switches for conditional gene expression in mammalian cells utilizing an in vivo screening approach. Methods Mol Biol 2016; 1316:127-40. [PMID: 25967058 DOI: 10.1007/978-1-4939-2730-2_11] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Artificial RNA switches are an emerging class of genetic controllers suitable for synthetic biology applications. Aptazymes are fusions composed of an aptamer domain and a self-cleaving ribozyme. The utilization of aptazymes for conditional gene expression displays several advantages over employing conventional transcription factor-based techniques as aptazymes require minimal genomic space, fulfill their function without the need of protein cofactors, and most importantly are reprogrammable with respect to ligand selectivity and the RNA function to be regulated. Technologies that enable the generation of aptazymes to defined input ligands are of interest for the construction of biocomputing devices and biosensing applications. In this chapter we present a method that facilitates the in vivo screening of randomized pools of aptazymes in mammalian cells.
Collapse
Affiliation(s)
- Charlotte Rehm
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | | | | |
Collapse
|
8
|
Räz MH, Hollenstein M. Probing the effect of minor groove interactions on the catalytic efficiency of DNAzymes 8-17 and 10-23. MOLECULAR BIOSYSTEMS 2016; 11:1454-61. [PMID: 25854917 DOI: 10.1039/c5mb00102a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
DNAzymes (Dz) 8-17 and 10-23 are two widely studied and well-characterized RNA-cleaving DNA catalysts. In an effort to further improve the understanding of the fragile interactions and dynamics of the enzymatic mechanism, this study examines the catalytic efficiency of minimally modified DNAzymes. Five single mutants of Dz8-17 and Dz10-23 were prepared by replacing the adenine residues in the corresponding catalytic cores with 3-deazaadenine units. Kinetic assays were used to assess the effect on the catalytic activity and thereby identify the importance of hydrogen bonding that arises from the N3 atoms. The results suggest that modifications at A15 and A15.0 of Dz8-17 have a significant influence and show a reduction in catalytic activity. Modification at each location in Dz10-23 results in a decrease of the observed rate constants, with A12 appearing to be the most affected with a reduction of ∼80% of kobs and ∼25% of the maximal cleavage rate compared to the wild-type DNAzyme. On the other hand, modification of A12 in Dz8-17 showed an ∼130% increase in kobs, thus unraveling a new potential site for the introduction of chemical modifications. A pH-profile analysis showed that the chemical cleavage step is rate-determining, regardless of the presence and/or location of the mutation. These findings point towards the importance of the N3-nitrogens of certain adenine nucleotides located within the catalytic cores of the DNAzymes for efficient catalytic activity and further suggest that they might directly partake in maintaining the appropriate tertiary structure. Therefore, it appears that minor groove interactions constitute an important feature of DNAzymes as well as ribozymes.
Collapse
Affiliation(s)
- Michael H Räz
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
| | | |
Collapse
|
9
|
Hollenstein M. DNA Catalysis: The Chemical Repertoire of DNAzymes. Molecules 2015; 20:20777-804. [PMID: 26610449 PMCID: PMC6332124 DOI: 10.3390/molecules201119730] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 11/10/2015] [Accepted: 11/11/2015] [Indexed: 12/24/2022] Open
Abstract
Deoxyribozymes or DNAzymes are single-stranded catalytic DNA molecules that are obtained by combinatorial in vitro selection methods. Initially conceived to function as gene silencing agents, the scope of DNAzymes has rapidly expanded into diverse fields, including biosensing, diagnostics, logic gate operations, and the development of novel synthetic and biological tools. In this review, an overview of all the different chemical reactions catalyzed by DNAzymes is given with an emphasis on RNA cleavage and the use of non-nucleosidic substrates. The use of modified nucleoside triphosphates (dN*TPs) to expand the chemical space to be explored in selection experiments and ultimately to generate DNAzymes with an expanded chemical repertoire is also highlighted.
Collapse
Affiliation(s)
- Marcel Hollenstein
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| |
Collapse
|
10
|
Adornetto G, Porchetta A, Palleschi G, Plaxco KW, Ricci F. A general approach to the design of allosteric, transcription factor-regulated DNAzymes. Chem Sci 2015; 6:3692-3696. [PMID: 28706715 PMCID: PMC5496187 DOI: 10.1039/c5sc00228a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/09/2015] [Indexed: 12/26/2022] Open
Abstract
Here we explore a general strategy for the rational design of nucleic acid catalysts that can be allosterically activated by specific nucleic-acid binding proteins. To demonstrate this we have combined a catalytic DNAzyme sequence and the consensus sequence recognized by specific transcription factors to create a construct exhibiting two low-energy conformations: a more stable conformation lacking catalytic activity and lacking the transcription factor binding site, and a less stable conformation that is both catalytically active and competent to bind the transcription factor. The presence of the target transcription factor pushes the equilibrium between these states towards the latter conformation, concomitantly activating catalysis. To demonstrate this we have designed and characterized two peroxidase-like DNAzymes whose activities are triggered upon binding either TATA binding protein or the microphthalmia-associated transcription factor. Our approach augments the current tool kit for the allosteric control of DNAzymes and ribozymes and, because transcription factors control many key biological functions, could have important clinical and diagnostic applications.
Collapse
Affiliation(s)
- G Adornetto
- Dipartimento di Scienze e Tecnologie Chimiche University of Rome Tor Vergata , Via della Ricerca Scientifica , Rome 00133 , Italy .
| | - A Porchetta
- Dipartimento di Scienze e Tecnologie Chimiche University of Rome Tor Vergata , Via della Ricerca Scientifica , Rome 00133 , Italy .
- Consorzio Interuniversitario Biostrutture e Biosistemi "INBB" , Rome 00136 , Italy
| | - G Palleschi
- Dipartimento di Scienze e Tecnologie Chimiche University of Rome Tor Vergata , Via della Ricerca Scientifica , Rome 00133 , Italy .
- Consorzio Interuniversitario Biostrutture e Biosistemi "INBB" , Rome 00136 , Italy
| | - K W Plaxco
- Department of Chemistry and Biochemistry , University of California Santa Barbara , Santa Barbara , California 93106 , USA
- Center for Bioengineering , University of California Santa Barbara , Santa Barbara , California 93106 , USA
| | - F Ricci
- Dipartimento di Scienze e Tecnologie Chimiche University of Rome Tor Vergata , Via della Ricerca Scientifica , Rome 00133 , Italy .
- Consorzio Interuniversitario Biostrutture e Biosistemi "INBB" , Rome 00136 , Italy
| |
Collapse
|