A Novel Small RNA-Cleaving Deoxyribozyme with a Short Binding Arm

Area of Science:

• Biochemistry
• Molecular Biology
• Synthetic Biology

Background:

• Deoxyribozymes catalyze sequence-specific RNA cleavage, with deoxyribozyme 8-17 being a widely used example.
• The existence and catalytic mechanisms of other RNA-cleaving deoxyribozymes remain largely unexplored.

Purpose of the Study:

• To identify and characterize novel RNA-cleaving deoxyribozymes.
• To investigate the catalytic mechanism and substrate specificity of a newly discovered deoxyribozyme, 10-12opt.
• To compare the catalytic capabilities of 10-12opt with the established 8-17 deoxyribozyme.

Main Methods:

• Isolation and characterization of a novel RNA-cleaving deoxyribozyme, 10-12opt.
• Kinetic analysis of RNA cleavage at UN dinucleotide junctions.
• Mutational analysis to elucidate the catalytic mechanism and identify key residues.
• Comparative cleavage assays using microRNA substrates.

Main Results:

• A novel deoxyribozyme, 10-12opt, was identified with a compact catalytic core and a short binding arm.
• 10-12opt preferentially cleaves RNA at UN dinucleotide junctions with a observed rate constant of 0.9 h⁻¹ for UU cleavage.
• Mutational analysis indicated a critical role for a riboguanosine residue downstream of the cleavage site, likely involving its carbonyl O6 atom in catalysis.
• 10-12opt demonstrated efficacy in cleaving specific microRNA sequences not efficiently cleaved by deoxyribozyme 8-17.

Conclusions:

• Deoxyribozyme 10-12opt represents a novel class of RNA-cleaving DNA enzymes with a distinct catalytic structure compared to deoxyribozyme 8-17.
• The findings suggest the existence of a broader sequence space for DNA molecules capable of site-specific RNA cleavage.
• This discovery holds potential for advancing applications in biotechnology, DNA computing, and environmental sensing.