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Mutational analysis of RNA structures and sequences postulated to affect 3' processing of M1 RNA, the RNA component
1Department of Chemistry, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea.
Abstract:
When the rnpB gene encoding M1 RNA, the RNA component of Escherichia coli RNase P, is transcribed, the primary M1 RNA transcript (pM1 RNA) is produced and subsequently processed at the 3' end to generate the mature M1 RNA. To study features of pM1 RNA thought to be involved in RNA processing, systematic mutations were introduced in sequence elements and secondary structures surrounding the processing site using p23 RNA, a truncated pM1 RNA transcribed from the internally deleted rnpB gene, as a model substrate and the processing of its mutant derivatives was analyzed in vivo and in vitro. Neither the alteration of two bases forming the processing site nor the disruption of secondary structures surrounding the site significantly affected the processing efficiency although the secondary structures were required for maintaining RNA stability. In contrast, mutations at the rne-dependent site, GAUUU, immediately 3' to the processing site inhibited the processing and the extent of the inhibition varied with the altered sequences. Furthermore, the processing of the mutants of the rne-dependent site as well as wild-type p23 RNA was inhibited in an E. coli rnets strain at the nonpermissive temperature.
Insights
Investigating M1 RNA processing in E. coli revealed that while the processing site and surrounding structures are crucial for stability, mutations in the downstream
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The rnpB gene encodes M1 RNA, the essential RNA component of Escherichia coli RNase P.
- Primary M1 RNA (pM1 RNA) undergoes 3' end processing to yield mature M1 RNA.
Purpose of the Study:
- To investigate sequence elements and secondary structures influencing pM1 RNA processing.
- To analyze the role of the rne-dependent site in M1 RNA maturation.
Main Methods:
- Systematic mutations were introduced into p23 RNA, a truncated pM1 RNA model substrate.
- Mutant derivatives were analyzed for processing efficiency in vivo and in vitro.
- Studies were conducted in both wild-type and rnets mutant E. coli strains.
Main Results:
- Alterations at the processing site or disruption of surrounding secondary structures did not significantly impact processing efficiency.
- Secondary structures were found to be essential for maintaining RNA stability.
- Mutations at the downstream GAUUU (rne-dependent) site inhibited processing, with varying effects based on sequence changes.
- Processing was inhibited in an E. coli rnets strain at nonpermissive temperatures.
Conclusions:
- The rne-dependent site, not the immediate processing site or surrounding secondary structures, plays a critical role in regulating pM1 RNA processing.
- RNA stability is linked to secondary structure integrity.
- RNase E (encoded by rne) is involved in the processing pathway of M1 RNA.