Article

General deoxyribozyme-catalyzed synthesis of native 3 '-5 ' RNA linkages

Department of Chemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, United States
Journal of the American Chemical Society (Impact Factor: 11.44). 10/2005; 127(38):13124-5. DOI: 10.1021/ja0533702
Source: PubMed

ABSTRACT An elusive goal for nucleic acid enzymology has been deoxyribozymes that ligate RNA rapidly, sequence-generally, with formation of native 3'-5' linkages, and in preparatively useful yield. Using in vitro selection, we have identified Mg2+- and Zn2+-dependent deoxyribozymes that simultaneously fulfill all four of these criteria. The new deoxyribozymes operate under practical incubation conditions and have modest RNA substrate sequence requirements, specifically D downward arrowRA for 9DB1 and A downward arrowR for 7DE5 (D = A, G, or U; R = A or G). These requirements are comparable to those of deoxyribozymes such as 10-23 and 8-17, which are already widely used as biochemical tools for RNA cleavage. We anticipate that the 9DB1 and 7DE5 deoxyribozymes will find immediate practical application for RNA ligation.

0 Bookmarks
 · 
103 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Preparation of site-specifically labeled RNA for spectroscopic studies is a multistep process and requires handling of delicate samples. This chapter is focused on the synthesis of spin-labeled RNA using convertible nucleosides and the application of the deoxyribozyme 9DB1* for the ligation of RNA fragments. The convertible nucleoside approach enables the attachment of nitroxyls as paramagnetic reporters at the exocyclic amino groups of cytidine, adenosine, and guanosine nucleobases in synthetic RNA. The deoxyribozyme 9DB1* is a synthetic single-stranded DNA with RNA ligase activity that can be used as an alternative to protein enzymes (T4 RNA/DNA ligases) for covalently joining RNA fragments via native 3'-5' phosphodiester bonds. The combination of solid-phase synthesis and DNA-catalyzed RNA ligation provides reliable access to site-specifically labeled functional RNAs for spectroscopic studies. A particular advantage of using deoxyribozymes for RNA ligation lies in the mild reaction conditions that prevent chemical damage to sensitive labels. As an example, we describe a detailed protocol for the synthesis of TEMPO-labeled SAM-I riboswitch RNA.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Among the deoxyribozymes catalyzing the ligation of two RNA substrates, 7S11 generates a branched RNA containing a 2',5'-linkage. We have attached the small fluorogenic probe Bimane to the triphosphate terminated RNA substrate and utilized emission intensity and anisotropy to follow structural rearrangements leading to a catalytically active complex upon addition of Mg(2+). Bimane coupled to synthetic oligonucleotides is quenched by nearby guanines via photoinduced electron transfer. The degree of quenching is sensitive to changes in the base pairing of the residues involved and in their distances to the probe. These phenomena permit the characterization of various sequential processes in the assembly and function of 7S11: binding of Mg(2+) to the triphosphate moiety, release of quenching of the probe by the 5'-terminal G residues of R-RNA as they engage in secondary base-pair interactions, local rearrangement into a distinct active conformation, and continuous release of the Bimane-labeled pyrophosphate during the course of reaction at 37°C. It was possible to assign equilibrium and rate constants and structural interpretations to the sequence of conformational transitions and catalysis, information useful for optimizing the design of next generation deoxyribozymes. The fluorescent signatures, thermodynamic equilibria and catalytic function of numerous mutated (base/substituted) molecules were examined. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.
    Nucleic Acids Research 12/2014; 43(1). DOI:10.1093/nar/gku1268 · 8.81 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Breast cancer is one of the most commonly diagnosed cancers among females worldwide. Early detection of breast cancer is of vital importance to the reduction of the mortality rate. However, the lack of specific biomarkers that can effectively identify breast cancer cells limits the ability for early diagnosis of breast cancer. RNA-cleaving fluorogenic DNAzymes (RFDs), which can be produced through the Systematic Evolution of Ligands by Exponential enrichment (SELEX) process, are catalytic DNA molecules capable of generating a fluorescent signal when the appropriate target is bound. In this study, we carried out a SELEX experiment to select for RFDs that are active in the cell lysate of MDA-MB-231, a model breast cancer cell line. We obtained a RFD probe, named AAI2-5, that can detect MDA-MB-231 at a concentration of cell lysate proteins as low as 0.5 μg/mL (which is equivalent to ~5,000 cell/mL). AAI2-5 is capable of distinguishing MDA-MB-231 cells from normal cells as well as other types of tumor cells, including other subtypes of breast cancer cells. Moreover, AAI2-5 responded positively to more than 90% of malignant breast tumors. This report is the first study to explore the RFD system for the detection of cancer cells. The results suggest that RFD can be potentially applied for the diagnosis and treatment of breast cancer in the future.
    Analytical Chemistry 12/2014; 87(1). DOI:10.1021/ac5031557 · 5.83 Impact Factor

Preview

Download
1 Download
Available from