Preparation and Properties of mRNA 5-cap Structure

Abstract

The 5´-terminus of eukaryotic messenger RNA (mRNA) molecules contains an unique structure, viz. a dinucleoside 5´,5´-triphosphate moiety where the terminal nucleoside is 7-methylguanosine. This 5´-cap structure serves as a site of recognition for numerous enzymes involved in splicing, transport and translation of mRNA, and protects mRNA against intracellular exonucleases. In addition, viral RNA polymerases use capped mRNA sequences of the host cell as primers for viral RNA synthesis. Understanding of molecular mechanism of all these processes requires detailed information on the chemical properties of the cap structure, including capability to prepare conjugates and structural analogs of the cap for research tools. This review tends to summarize the present knowledge on various aspects of the chemistry of the cap structure, including chemical stability and mechanisms of breakdown, protolytic and complexing equilibria, stacking interactions and synthetic methodology.

A kinetic study on the chemical cleavage of nucleoside diphosphate sugars

“…The rate of the reaction depends on the configuration of the sugar and the metal-ion employed. Interestingly, metal ions that enhance the cleavage of RNA 8c or dinucleoside oligophosphates 14 do not seem to be effective catalysts in this case. The products of the spontaneous cleavage of UDP-Glc (1a) have been reported to depend on conditions; 13b while a uridine 5 0 -monophosphate (5 0 -UMP; 2a) and cyclic glucose 1,2-phosphate (2b) are produced under neutral and alkaline conditions (Scheme 1, Route A), uridine 5 0 -diphosphate (5 0 -UDP; 2c) has been observed as the predominant primary product under acidic conditions (Scheme 1, Route B).…”

7,5′-O-Dibenzylinosines: Synthesis and Studies on Their Conformational Properties

“…This is in agreement with the preferred anti conformation reported for 7-methyl guanosine. [2] 3. The proposed conformations for 6A and 6B are likely to result from the stabilization brought about by the electrostatic interaction between the positively charged base and the high electron density of the 5 -benzyl moiety.…”

“…[1] Moreover, 7-methylguanosine (1) (Figure 1) is present in the mRNA 5 -cap structure that serves as a recognition site for numerous enzymes. [2] The positive charge of the imidazole ring of the guanine base 696 E. Casanova et al in both examples is essential for enzyme recognition. Therefore, model compounds modified at position N7 of guanine have been subjected to numerous studies to better understand the role of this site in biological interactions.…”

Synthesis of Capped RNA using a DMT Group as a Purification Handle

“…[1] Modern chemical synthesis of capped RNA has been achieved using two different strategies. [2,3] One approach involves first the synthesis of a variety of analogues of the dinucleotide cap structure that are then used during in vitro transcription for enzymatic preparation of capped RNA. [4][5][6][7][8] The methylated guanosine of these synthetic dinucleotide cap structures generally have a 2 -or 3 -OCH 3 group [9,10] or locked ribose ring [11] to prevent incorporation in the reverse orientation, and many also have modified bases [5] or modified phosphate linkages.…”