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Secondary structure of the RNA component of a nuclear/mitochondrial ribonucleoprotein
1Department of Developmental Biology, Stanford University School of Medicine, California 94305-5427.
Abstract:
RNase mitochondrial RNA processing (MRP) is a site-specific endoribonuclease located in both the nucleus and mitochondria of vertebrate cells. The enzyme is a ribonucleoprotein whose RNA component has been shown to be encoded by a nuclear gene. Because RNase MRP is particular in its substrate requirement, RNA-RNA interaction has been proposed as important for the cleavage reaction. A secondary structure of this RNA from mouse cells has been derived by chemical modification of in vivo MRP RNA in ribonucleoprotein form, as isolated free RNA, and as RNA synthesized in vitro. Full-length MRP RNA appears to adopt a conformation containing a significant number of single-stranded residues and may form a pseudoknot. The data are consistent with both the RNA within the ribonucleoprotein and the free RNA possessing comparable secondary structures and suggest a possible site of interaction between enzyme and substrate. The human MRP RNA can be folded into a conformation very similar to that predicted for the mouse MRP RNA. A more limited analysis of human MRP RNA is consistent with the structure proposed for the mouse species.
Insights
Mitochondrial RNA processing (MRP) RNase is a ribonucleoprotein crucial for RNA cleavage. Its RNA component forms a specific secondary structure, potentially involving a pseudoknot, guiding enzyme-substrate interactions.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- RNase mitochondrial RNA processing (MRP) is a site-specific endoribonuclease found in vertebrate cell nuclei and mitochondria.
- It is a ribonucleoprotein complex with an RNA component encoded by a nuclear gene.
- RNA-RNA interactions are hypothesized to be critical for RNase MRP's substrate cleavage due to its specific requirements.
Purpose of the Study:
- To determine the secondary structure of mouse MRP RNA.
- To compare the structure of MRP RNA in its ribonucleoprotein form, as free RNA, and as in vitro synthesized RNA.
- To investigate the structural similarity between mouse and human MRP RNA.
Main Methods:
- Chemical modification of in vivo MRP RNA in ribonucleoprotein form.
- Analysis of isolated free MRP RNA.
- Analysis of in vitro synthesized MRP RNA.
- Secondary structure prediction and comparison between mouse and human MRP RNA.
Main Results:
- Full-length mouse MRP RNA adopts a conformation with numerous single-stranded residues, possibly forming a pseudoknot.
- The secondary structures of MRP RNA in ribonucleoprotein and free forms are comparable.
- The derived secondary structure for human MRP RNA closely resembles that of mouse MRP RNA.
Conclusions:
- The secondary structure of MRP RNA is conserved between mouse and human species.
- The proposed structure provides insights into potential enzyme-substrate interaction sites.
- RNase MRP's RNA component plays a crucial role in its catalytic activity and substrate specificity.