title: The influence of the C5 substituent on the 2-thiouridine desulfuration pathway and the conformational analysis of the resulting 4-pyrimidinone products.
abstract: In recent years, increasing attention has been focused on the posttranscriptional modifications present in transfer RNAs (tRNAs), which have been suggested to constitute another level of regulation of gene expression. The most representative among them are the 5-substituted 2-thiouridines (R5S2U), which are located in the wobble position of the anticodon and play a fundamental role in the tuning of the translation process. On the other hand, sulfur-containing biomolecules are the primary site for the attack of reactive oxygen species (ROS). We have previously demonstrated that under in vitro conditions that mimic oxidative stress in the cell, the S2U alone or bound to an RNA chain undergoes desulfuration to yield uridine and 4-pyrimidinone nucleoside (H2U) products. The reaction is pH- and concentration-dependent. In this study, for the first time, we demonstrate that the substituent at the C5 position of the 2-thiouracil ring of R5S2Us influences the desulfuration pathway, and thus the products ratio. As the substituent R changes, the amount of R5H2U increases in the order H->CH3O->CH3OC(O)CH2->HOC(O)CH2NHCH2-≈ CH3NHCH2-, and this effect is more pronounced at lower pH. The conformational analysis of the resulting R5H2U products indicates that independent of the nature of the R5 substituent, the R5H2U nucleosides predominantly adopt a C2'-endo sugar ring conformation, as opposed to the preferred C3'-endo conformation of the parent R5S2Us.
authors.affiliation: Institute of Organic Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, Lodz, Poland.
authors.forename: Paulina
authors.initials: P
authors.lastname: Bartos
authors.affiliation: Institute of Organic Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, Lodz, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Ebenryter-Olbinska
authors.affiliation: Institute of Organic Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, Lodz, Poland. Electronic address: elzbieta.sochacka@p.lodz.pl.
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Sochacka
authors.affiliation: Department of Bioorganic Chemistry, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland. Electronic address: bnawrot@cbmm.lodz.pl.
authors.forename: Barbara
authors.initials: B
authors.lastname: Nawrot
mesh_terms: D006801:Humans; D008958:Models, Molecular; D018384:Oxidative Stress; D011744:Pyrimidinones / Q000378:metabolism*; D012343:RNA, Transfer / Q000737:chemistry*; D013891:Thiouridine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: C105273:2-thiouridine; D011744:Pyrimidinones; D013891:Thiouridine; D012343:RNA, Transfer
keywords: 2-Thiouridine; 4-Pyrimidinone riboside; Conformational analysis; Desulfuration; Oxidative stress; tRNA