The hammerhead ribozyme: structure, catalysis, and gene regulation.

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• Hammerhead ribozyme catalysis understanding was hindered by discrepancies between crystal structures and biochemical data.
• Earlier studies focused on minimal self-cleaving motifs, not full-length ribozymes.

Purpose of the Study:

• To unify the structural and biochemical understanding of hammerhead ribozyme catalysis.
• To elucidate the catalytic mechanism involving tertiary contacts and invariant residues.

Main Methods:

• Analysis of new crystal structures of full-length hammerhead ribozymes.
• Integration of biochemical experimental results with structural data.

Main Results:

• A tertiary contact distal to the active site significantly enhances hammerhead ribozyme catalytic activity.
• A proposed mechanism involves invariant residue G12 as a general base and the 2'-OH of invariant G8 as a general acid.
• This mechanism aligns with both structural and biochemical findings.

Conclusions:

• A unified understanding of hammerhead ribozyme catalysis is now achievable through integrated structural and biochemical approaches.
• The hammerhead ribozyme's presence in mammalian mRNAs suggests novel roles in genetic regulation beyond its viral origins.