Quantitative Assessment of mRNA Cap Analogues as Inhibitors of in Vitro Translation

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• 作者：Aili Cai ; Marzena Jankowska-Anyszka ; Adrian Centers ; Lidia Chlebicka ; Janusz Stepinski ; Ryszard Stolarski ; Edward Darzynkiewicz ; and Robert E. Rhoads
• 刊名：Biochemistry
• 出版年：1999
• 出版时间：June 29, 1999
• 年：1999
• 卷：38
• 期：26
• 页码：8538 - 8547
• 全文大小：161K
• 年卷期：v.38,no.26(June 29, 1999)
• ISSN：1520-4995

文摘

Fifty-eight analogues of the 5'-terminal 7-methylguanosine-containing cap of eukaryoticmessenger RNA were synthesized and tested for their ability to inhibit in vitro protein synthesis. A newalgorithm was developed for extracting K_I, the dissociation constant for the cap analogue·eIF4E complex,from protein synthesis data. The results indicated that addition of a methyl group to the N2 of guanineproduced more inhibitory compounds, but addition of a second methyl group to N2 decreased the levelof inhibition dramatically. Aryl substitution at N7 improved the efficacy of guanine nucleosidemonophosphate analogues. Substitution of the aromatic ring at the para position with methyl or NO₂groups abolished this effect, but substitution with Cl or F enhanced it. By contrast, aryl substitution at N7in nucleoside di- or triphosphate analogues produced only minor effects, both positive and negative. Byfar the strongest determinants of inhibitory activity for cap analogues were phosphate residues. Thebeneficial effect of more phosphate residues was related more to anionic charge than to the number ofphosphate groups per se. The second nucleotide residue in analogues of the form m⁷GpppN affectedinhibitory activity in the order G > C > U > A, but there was no effect of 2'-O-modification. Openingthe first ribose ring of m⁷GpppG analogues dramatically decreased activity, but alterations at the 2'-position of this ribose had no effect. Non-nucleotide-based cap analogues containing benzimidazolederivatives were inhibitory, though less so than those containing 7-methylguanine.