Thermodynamic and structural contributions of the 6-thioguanosine residue to helical properties of RNA

• Published in: Scientific reports 2019-03, Vol.9 (1), p.4385, Article 4385
• Main Authors: Gładysz, Michał, Andrałojć, Witold, Czapik, Tomasz, Gdaniec, Zofia, Kierzek, Ryszard
• Format: Article
• Language: English
• Subjects: 631/45/500; 631/45/535/878/1263; 631/92/2783; Adenosine; Base pairs; Base Sequence; Chloride; Circular Dichroism; Data processing; Guanine Nucleotides - chemistry; Guanosine; Guanosine - analogs & derivatives; Guanosine - chemistry; Humanities and Social Sciences; Magnetic Resonance Spectroscopy; multidisciplinary; Nucleic Acid Conformation; Nucleic acids; Nucleotide sequence; Organophosphorus Compounds - chemistry; Proteins; Ribonucleic acid; RNA; RNA - chemistry; RNA, Double-Stranded; Science; Science (multidisciplinary); Thionucleosides - chemistry
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-40715-2

Thionucleotides, especially 4-thiouridine and 6-thioguanosine, are photosensitive molecules that photocrosslink to both proteins and nucleic acids, and this feature is a major reason for their application in various investigations. To get insight into the thermodynamic and structural contributions of 6-thioguanosine to the properties of RNA duplexes a systematic study was performed. In a series of RNA duplexes, selected guanosine residues located in G-C base pairs, mismatches (G-G, G-U, and G-A), or 5′ and 3′-dangling ends were replaced with 6-thioguanosine. Generally, the presence of 6-thioguanosine diminishes the thermodynamic stability of RNA duplexes. This effect depends on its position within duplexes and the sequence of adjacent base pairs. However, when placed at a dangling end a 6-thioguanosine residue actually exerts a weak stabilizing effect. Furthermore, the structural effect of 6-thioguanosine substitution appears to be minimal based on NMR and Circular Dichroism (CD) data.