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Efficient hammerhead ribozymes targeted to the polycistronic Sendai virus P/C mRNA. Structure-function relationships
1Department of Immunology/Microbiology, Rush Medical College, Chicago, Illinois 60612, USA.
The Journal of Biological Chemistry
|January 17, 1997
Summary
Hammerhead ribozymes targeting Sendai virus mRNA showed varying efficacy based on design. Optimal intracellular ribozyme design requires balancing hybridization arm length and nonhybridizing extraneous sequences for stability and function.
Area of Science:
- Molecular Biology
- Virology
- Biochemistry
Background:
- Sendai virus P/C mRNA encodes essential P and C proteins via overlapping reading frames.
- Understanding protein function in virus replication necessitates control over mRNA expression.
Purpose of the Study:
- To investigate the functional impact of hammerhead ribozyme design on Sendai virus P/C mRNA cleavage.
- To compare ribozyme efficacy in both cell-free and intracellular environments.
Main Methods:
- Synthesized and expressed identical hammerhead ribozymes in vitro and in transfected cells.
- Assessed ribozyme efficiency by varying hybridization arm length (HAL) and nonhybridizing extraneous sequences (NES).
- Evaluated ribozyme stability against ribonuclease T2 digestion.
Main Results:
- Ribozymes with longer HAL (13-mer) were more efficient in cell-free assays, while shorter HAL (9-mer) were ineffective intracellularly.
- Minimizing NES enhanced in vitro efficiency but reduced intracellular activity.
- The most effective intracellular ribozyme (Rz13st) featured NES that formed stem-loop structures, increasing stability and achieving ~95% inhibition of P gene expression.
Conclusions:
- Intracellular ribozyme design must optimize parameters for productive ribozyme:substrate duplex formation.
- Enhancing RNA stability through structural elements like stem-loops is crucial for effective intracellular ribozyme function.