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Flavin recognition by an RNA aptamer targeted toward FAD
Manami Roychowdhury-Saha1, Susan M Lato, Eric D Shank
1Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, USA.
Biochemistry
|February 20, 2002
Summary
Researchers identified novel RNA aptamers that bind flavin adenine dinucleotide (FAD). These FAD-binding RNA structures are key for designing new redox ribozymes and understanding early biological catalysis.
Area of Science:
- Biochemistry
- Molecular Biology
- Chemical Biology
Background:
- Flavin adenine dinucleotide (FAD) is a crucial cofactor in biological redox reactions.
- Understanding RNA-cofactor interactions is vital for designing novel ribozymes and exploring RNA World scenarios.
Purpose of the Study:
- To identify RNA aptamers that specifically recognize flavin adenine dinucleotide (FAD) using the SELEX method.
- To characterize the structural and functional properties of these novel FAD-binding RNA aptamers.
Main Methods:
- Systematic Evolution of Ligands by Exponential Enrichment (SELEX) to isolate FAD-binding aptamers.
- Mutant aptamer analysis, S1 nuclease probing, and comparative sequence analysis to determine the core binding structure.
- Circular dichroism spectroscopy to investigate RNA conformational changes upon FAD binding.
Main Results:
- A simple 45-nucleotide helical RNA structure with internal bulges was identified as the core FAD-binding element.
- The aptamers exhibit high specificity for the isoalloxazine nucleus of FAD, distinguishing them from FMN and riboflavin aptamers.
- FAD binding induces a conformational change in the RNA, which requires magnesium and functions across a broad pH range (4.5-8.9).
Conclusions:
- The identified RNA aptamers specifically recognize FAD and are structurally and functionally distinct from previously known flavin aptamers.
- These aptamers' ability to bind FAD and their cofactor-dependent characteristics suggest their potential utility in designing new flavin-dependent redox ribozymes.
- The findings contribute to our understanding of RNA-cofactor interactions and the evolution of catalytic RNAs.