A minimal RNA-cleaving DNAzyme and its catalytic mechanism

Area of Science:

• Biochemistry
• Molecular Biology
• Synthetic Biology

Background:

• Natural enzymes are typically proteins or RNA, but artificial DNA molecules, known as DNAzymes, can also exhibit catalytic functions.
• DNAzymes can perform reactions like nucleic acid cleavage and ligation, expanding the possibilities of biocatalysis.

Purpose of the Study:

• To develop a minimal DNAzyme with RNA-cleaving activity using in vitro selection and structure-based design.
• To elucidate the catalytic mechanism and three-dimensional structure of this novel RNA-cleaving DNAzyme.

Main Methods:

• In vitro selection and secondary structure-based design were employed to create the minimal DNAzyme.
• X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy were used to determine the DNAzyme's 3D structure.
• The catalytic mechanism was investigated by analyzing the coordination of zinc ions and the interaction with substrate.

Main Results:

• A minimal DNAzyme with a two-nucleotide catalytic core and a three-nucleotide substrate core was successfully developed.
• The DNAzyme demonstrated strict Zn2+ dependence, functioning optimally at pH 7.0-7.5.
• Structural analysis revealed a B-DNA-like structure with a non-Watson-Crick base pair (A-G) crucial for catalysis, and proposed a mechanism involving Zn2+ and Zn(OH)+ ions.

Conclusions:

• The developed minimal DNAzyme is an efficient RNA-cleaving catalyst dependent on zinc ions.
• The study elucidated the structural basis and catalytic mechanism of this minimal DNAzyme, involving specific base pairing and metal ion coordination.
• This research contributes to the understanding and design of artificial enzymes with tailored catalytic activities.