Three-dimensional structure of a hammerhead ribozyme

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• The hammerhead ribozyme is a key catalytic RNA motif crucial for various biological processes.
• Its catalytic activity relies on a conserved core of nucleotides and specific base-paired stems.
• Understanding its structure is vital for deciphering its mechanism of action.

Purpose of the Study:

• To elucidate the three-dimensional structure of a hammerhead ribozyme-inhibitor complex.
• To identify structural features essential for the catalytic activity of the hammerhead ribozyme.
• To provide insights into the mechanism of RNA cleavage mediated by the hammerhead ribozyme.

Main Methods:

• X-ray crystallography was employed to determine the structure of the hammerhead ribozyme-inhibitor complex.
• High-resolution (2.6 A) structural data was obtained and analyzed.
• Structural analysis focused on base-paired stems, the catalytic core, and interactions with the inhibitor.

Main Results:

• The hammerhead ribozyme's base-paired stems adopt A-form helical structures.
• The catalytic core comprises two distinct structural domains: a uridine turn motif and a non-Watson-Crick duplex with a divalent-ion binding site.
• The DNA inhibitor's backbone is splayed near the cleavage site, suggesting a role in substrate destabilization.

Conclusions:

• The determined structure reveals key features of the hammerhead ribozyme's catalytic core and its interaction with an inhibitor.
• The findings suggest that the ribozyme destabilizes the substrate strand, facilitating cleavage.
• This structural information advances our understanding of ribozyme-mediated catalysis and RNA processing.