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Conformational study of DNA-RNA duplexes containing MMI substituted phosphodiester linkages by FTIR spectroscopy
H Gousset1, J Liquier, E Taillandier
1Laboratoire de Spectroscopie Biomoléculaire, URA CNRS 1430, UFR de Médecine, Bobigny, France.
Abstract:
Six methylene(methylimino) (MMI, Bhat et al. J. Org. Chem., 61, 8186, 1996) linked oligonucleotides a-f (* = MMI linkage; 5'-GCGT*TT*TT*TT*TT*TGCG-3') containing various combinations of 2'-O-methyl and 2'-fluoro substituent were synthesized as a model to study the global conformational change upon hybridization to the complement RNA. Fourier transform infrared (FTIR) spectroscopic technique has been used to study and compare the influence of these modifications on the solution conformation of 2'-modified MMI DNA-RNA duplexes. FTIR analysis of the single-stranded RNA (5'-CGCAAAAAAAAAACGC-3') and the modified oligonucleotides a-f showed that all sugar residues adopted a C3'-endo conformation (North-type). Stable duplexes were formed when oligonucleotides a-f were hybridized to the complement RNA. These duplexes retained the original C3'-endo conformation for all sugar residues, hallmark of an A-form of duplex. We postulate that the observed preorganization of the sugar residues and oligonucleotides containing 2'-modified MMI modifications may play an important role in both improving the recognition of RNA target and enhancing the stability of duplex formation with RNA.
Insights
Modified oligonucleotides with methylene(methylimino) linkages maintain an A-form duplex structure upon hybridization with RNA. These 2'-modified MMI DNA-RNA duplexes show enhanced stability and target recognition.
Area of Science:
- Oligonucleotide chemistry
- Biophysical chemistry
- Molecular recognition
Background:
- Methylene(methylimino) (MMI) linked oligonucleotides are synthetic analogs of nucleic acids.
- 2 eal-O-methyl and 2 eal-fluoro substituents can alter oligonucleotide properties.
- Understanding conformational changes upon hybridization is crucial for nucleic acid-based therapeutics.
Purpose of the Study:
- To synthesize and characterize 2 eal-modified MMI oligonucleotides.
- To investigate the conformational changes of these modified oligonucleotides upon hybridization with complementary RNA.
- To assess the impact of MMI modifications on duplex stability and RNA recognition.
Main Methods:
- Synthesis of six MMI-linked oligonucleotides with varying 2 eal-substituents.
- Fourier transform infrared (FTIR) spectroscopy to analyze solution conformation.
- Hybridization studies with complementary RNA sequences.
Main Results:
- All synthesized single-stranded MMI oligonucleotides adopted a C3 eal'-endo sugar pucker (North-type).
- Stable DNA-RNA duplexes were formed upon hybridization.
- The duplexes retained the C3 eal'-endo conformation, characteristic of the A-form duplex structure.
- The 2 eal'-modifications did not disrupt the overall duplex conformation.
Conclusions:
- The preorganization of sugar residues in 2 eal'-modified MMI oligonucleotides favors the A-form duplex structure.
- These modifications may enhance the stability of DNA-RNA duplexes.
- The observed properties suggest potential for improved RNA target recognition and therapeutic applications.