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Non-cognate template usage and alternative priming by a group II intron-encoded reverse transcriptase.
Tatiana Morozova1, Wooseok Seo, Steven Zimmerly
1Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada.
Journal of Molecular Biology
|February 6, 2002
Summary
Group II intron reverse transcriptases (RTs) can copy non-cognate RNAs when intron structure is disrupted. This alternative priming mechanism, observed in mitochondrial RNP particles, impacts retroprocessing events.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Group II introns are mobile genetic elements known for site-specific DNA insertion via homing.
- Their reverse transcriptases (RTs) are crucial for this process, but interactions with non-cognate substrates are poorly understood.
Purpose of the Study:
- To investigate how group II intron RTs interact with non-cognate RNA and DNA substrates.
- To elucidate the mechanism of alternative priming in disrupted intron structures.
Main Methods:
- Analysis of wild-type and mutant group II intron (aI2) RTs in mitochondrial RNP particles.
- Reverse transcription assays using endogenous and exogenous RNA and DNA templates.
- Characterization of primer utilization in alternative priming events.
Main Results:
- Wild-type aI2 RT reverse transcribes non-cognate RNAs in misfolded intron structures.
- Mutant introns with disrupted structures exhibit reduced RNA specificity and utilize alternative priming.
- Alternative priming involves a short, non-complementary DNA primer (approx. 10 nucleotides) and is specific to in vivo RT-RNA interactions.
Conclusions:
- Group II intron RTs can engage in non-cognate RNA reverse transcription under specific structural conditions.
- Alternative priming represents a novel mechanism with implications for intron deletions and other retroprocessing events.
- Understanding these mechanisms is key to comprehending the broader roles of group II introns in genome dynamics.