Dinucleotide junction cleavage versatility of 8-17 deoxyribozyme

Area of Science:

• Biochemistry
• Molecular Biology
• Catalysis

Background:

• Deoxyribozymes are DNA molecules with catalytic activity.
• The 8-17 deoxyribozyme is a known RNA-cleaving motif.
• Understanding deoxyribozyme specificity is crucial for molecular applications.

Purpose of the Study:

• To isolate novel deoxyribozymes capable of cleaving various RNA dinucleotide junctions.
• To characterize the sequence and catalytic properties of new 8-17 deoxyribozyme variants.
• To investigate the structural basis for the substrate specificity of these catalytic DNAs.

Main Methods:

• In vitro selection experiments were performed using a DNA library against RNA substrates.
• Sequence analysis was used to identify conserved nucleotides in isolated deoxyribozymes.
• Catalytic activity of selected deoxyribozyme variants was tested in trans with various RNA substrates.
• The requirement of metal ions for catalysis was assessed.

Main Results:

• Hundreds of 8-17 deoxyribozyme variants were isolated, showing broad dinucleotide cleavage capabilities.
• Four absolutely conserved nucleotides were identified within the 8-17 motif.
• Five representative variants cleaved 14 out of 16 possible RNA dinucleotide junctions.
• Manganese ions (Mn2+) were found to be essential for the broad cleavage activity of new variants.

Conclusions:

• The 8-17 deoxyribozyme motif can be evolved to cleave a wide range of RNA dinucleotide junctions.
• Conserved nucleotides likely form an enzymatic core, while other regions facilitate substrate recognition.
• The tertiary structure of 8-17 deoxyribozymes may involve a catalytic core and a structural facilitator for fine-tuning cleavage sites.
• These findings expand the repertoire of catalytic DNAs for RNA manipulation.